A method of obtaining images of an object, the device for its implementation and delivery of low-coherence optical radiation

 

Method and device can be used to obtain an image of the object when diagnosing the condition of human organs, as well as in technical diagnostics. Low-coherence optical radiation directed to the object under examination using an optical fiber through the optical system with the simultaneous lateral scanning by moving the distal end of the optical fiber on the surface of the transverse scan. Adjust associated with transverse scanning aberration of the optical path length through the permanence time of propagation of the radiation from the distal end of the optical fiber to a corresponding conjugate point in the plane of its image while moving the distal end of the optical fiber on the specified surface transverse scan. For this purpose, the optical system includes at least two lens component with positive refractive power, installed approximately confocal. Provides improved performance characteristics, obtaining undistorted flat image of a flat object, as well as increased lateral resolution. 3 N. and 32 C.p. f-crystals, 20 ill.

Device for obtaining images of an object using optical low-coherence radiation is fairly well known (see, for example, the device in U.S. Pat. USA№№5321501, 5383467, 5459570, 5582171, 6134003, the international application number WO 00/16034 and others) and are optically coupled to the source of low-coherence optical radiation, the optical interferometer and the photodetector associated with the processing unit and display. The interferometer is performed usually in the form of a Michelson interferometer (see, for example, X. Clivaz et al. "High resolution refiectometry in biological tissues", Opt.Lett. /Vol.17, No. l/January 1, 1992; J. A. Izatt, J. G. Fujimoto et al., "Optical coherence microscopy in scattering media, Opt.Lett/ Vol.19, No. 8/April 15, 1994, p.590-592) or interferometer of Mach-Zehnder interferometers (see, for example, J. A. Izatt, J. G. Fujimoto et al. "Micron-resolution Biomedical Imaging with optical coherence tomography". Optics &Photonic News, October 1993, Vol.4, No.10, p.14-19; U.S. Pat. U.S. No. 5582171, international application number WO 00/16034). Regardless of the specific scheme of the optical interferometer it traditionally contains one or is sustained fashion by the probe, often, fiber, performs the function of delivering low-coherence optical radiation to the object of study, and at the end of the support shoulder set reference mirror (for example, A. Sergeev et al., "In vivo optical coherence tomography of human skin microstructure", Proc.SPIE, v.2328, 1994, p. 144; X. J. Wang et al. Characterization of human scalp hairs by optical low coherence reflectometry. Opt. Lett./Vol.20, No.5, 1995, pp.524-526). To provide longitudinal scan of the investigated object reference mirror is combined with an element providing a mechanical displacement of the reference mirror (U.S. Pat. U.S. No. 5321501, 5459570), or fix the location of the reference mirror, and the vertical scanning is performed using a piezoelectric scanning element (U.S. Pat. Of the Russian Federation No. 2100787, 1997), or using a dispersion-lattice delay lines (K. F. Kwong, D. Yankelevich et al. 400-Hz mechanical scanning optical delay line, Optics Letters, Vol.18, No.7, April 1, 1993). Sometimes the optical layout of the interferometer is fully or partially implemented using optical elements with lumped parameters (U.S. Pat. U.S. No. 5383467), but most of the optical interferometers such appointment perform fiber (U.S. Pat. USA№№5321501, 5459570, 5582171).

The advantage of the device to obtain an image of an object using optical low-coherence of the radiation is the possibility of non-invasive diagnostics in health research and non-destructive control and technical diagnostics of various equipment.

Known improvements of the device to obtain an image of an object using optical low-coherence radiation is directed, in particular, to increase the resolution of the device (e.g., Art. W. Drexler at al. "In vivo ultrahigh-resolution optical coherence tomography". Opt. Lett./Vol.24, No-17/September 1, 1999), on the reduction of the inertia of the longitudinal scanning of the object (Pat. Of the Russian Federation No. 2100787), on the efficiency of the power source of the optical radiation at the optimum ratio signal/noise (for example, international application number WO 00/16034, Pat. Of the Russian Federation No. 2169347, 2001).

The probe, which is part of the measuring arm, performs the function of delivering low-coherence optical radiation to the object of study and performed, usually in the form of a fiber optic probe containing an optical fiber placed with the possibility of passing through low-coherence optical radiation from the proximal end of the probe to its distal end, and the optical system, which provides focusing of low-coherence optical radiation to the object under consideration and includes at least one lens component with positive refractive power, and a system poperen is sustained fashion the probe includes, typically, the length of the casing, provided with a longitudinal through hole, in which the longitudinal direction is placed optical fiber. The system cross-scan includes the actuator, which may be in the form of a piezoelectric element, a stepping motor, an electromagnetic system or an electrostatic system (U.S. Pat. U.S. No. 5321501, 5383467).

Known improvements probes included in a device for obtaining images of objects using optical low-coherence radiation, aimed in particular at ensuring the possibility of obtaining images of thin vessels (U.S. Pat. U.S. No. 55821721), to optimize the design of the probe from the point of view of obtaining the maximum amplitude of deflection of the optical beam with limited dimensions of the fiber optic probe (U.S. Pat. Of the Russian Federation No. 2148378, 2000).

The known device for obtaining images of the object using the low-coherence optical radiation implement essentially the same method of obtaining images of the object described, for example, in U.S. Pat. USA№№5321501, 5383467, 5459570, 5582171, Pat. Of the Russian Federation No. 2148378, which is the closest analogue of the developed method for doing odnovremenno on the inspected object and the reference optical path. These optical radiation directed to the object under examination through an optical system, which provides focusing of low-coherence optical radiation to the object being tested, while the cross-mentioned scanning optical radiation on the surface approximately orthogonal to the direction of propagation mentioned optical radiation. Then mixed optical radiation returning from the test object, and the optical radiation passed through the reference optical path, and display the intensity of the optical radiation returning from the test object using optical radiation, which is the result of this mixing. In addition, carry out a longitudinal scan of the investigated object, changing according to a given law, at least several tens of wavelengths of low-coherence optical radiation, the difference between the optical lengths of the paths for the low-coherence optical radiation directed to the object under examination, and low-coherence optical radiation directed to a reference path.

The closest analogue of the developed device to obtain an image of an object is the tion of optical radiation, the interferometer and at least one photodetector, the output of which is connected with the processing unit and display. The interferometer includes an optical related svetorasseivateley, the measuring and reference shoulders, while measuring the shoulder provided with a device for delivering low-coherence optical radiation, made in the form of fiber-optic probe. The said device delivering low-coherence optical radiation includes an optical fiber placed with the possibility of passing through low-coherence optical radiation from the proximal end of the said delivery device to its distal end, the optical system, which provides focusing of low-coherence optical radiation to the object under consideration and includes at least a first lens component with positive refractive power, and a system of transverse scanning low-coherence optical radiation. Optical fiber is part of the system transverse scan, which is configured to move the distal end of the optical fiber on the surface of the cross-scan direction approximately perpendicular to the axis of optionsmenu is a fiber optic probe, part of the optical interferometer according to the above U.S. Pat. Of the Russian Federation No. 2148378. Fiber optic probe contains optically coupled to the optical fiber placed with the possibility of passing through low-coherence optical radiation from the proximal end of the fiber optic probe to its distal end, and the optical system, which provides focusing of low-coherence optical radiation to the object under consideration and includes at least a first lens component with positive refractive power, and a system of transverse scanning low-coherence optical radiation. Optical fiber is part of the system transverse scan, which is configured to move the distal end of the optical fiber on the surface of the cross-scan direction approximately perpendicular to the axis of the optical fiber.

The disadvantage of this method, which is the closest analogue, as well as the device, its implements, and the fiber-optic probe that performs the function of delivering low-coherence optical radiation to the object under examination and are part of the device according to U.S. Pat. Of the Russian Federation No. 2148378, as well as other known those who th radiation, is that the resulting image of a flat object looks crooked. This curvature is due to the peculiarity of the construction of the image of the interference signal resulting from the mixing of optical radiation returning from the test object, and the radiation transmitted through the reference path. It is known that the interference signal occurs with equal optical lengths of the paths for the low-coherence optical radiation directed to the object under examination, and low-coherence optical radiation directed to a reference path. However, the time distribution of low-coherence optical radiation from points on a flat surface transverse scanning, different remote from the optical axis of the device, to the corresponding conjugate points in the image plane varies. Therefore, while the optical path length of the low-coherence optical radiation propagating along the reference path unchanged, the optical path length of the low-coherence optical radiation directed to the object under examination, while transverse scanning is not constant, which leads to a distortion of the generated image. This can be seen in Fig.Ie image using known technical solutions. In Fig.8, 9 and 10 show, respectively, the lines 31, 34, 35, corresponding to the geometric place of the points, to which the optical path length of the low-coherence optical radiation directed to the object under examination, has the same value when the distribution from the corresponding conjugate points on a flat surface 28 of the transverse scan, different remote from the optical axis of the device. From the drawings it is seen that the lines 31, 34, 35 have a curvature. In addition, when the surface of the cross-scan has a curvature, for example, when the optical fiber in the fiber optic probe performs the function of elastic console, there is an additional aberration, which also contributes to the curvature of the formed image. Another disadvantage of the known technical solutions is the fixed location of the focus is directed on the object low-coherence optical radiation, while the window location coherence for longitudinal scanning is changed, which limits the lateral resolution of the method and implement its devices, especially when deep scanning. The reason is the strong diffraction divergence ostrovoduzhnogo islicensed d=2/4where- the diameter of the waist of the beam,- wavelength=3,1416. Consequently, for typical parameters=0.005 mm,=1300 nm, the depth of field is only 0.015 mm (15m). To ensure a high transverse resolution at greater depths, the longitudinal scan in the known devices produce synchronous scanning position of a focal spot, i.e. where you want to focus optical radiation, by moving one of the lenses of the optical system, and window positions coherence by scanning the difference of the lengths of the interferometer arms. This approach was first demonstrated in Art. Izatt, J. A., She, MR, Owen, GM, Swanson, E. A and Fujimoto, JG, 1994, Optical coherence microscopy in scattering media, Optics Letts. 19, 590-592, and was called optical coherence microscopy (ACM). All known implementing ACM is performed by executing these two scans (the position of focus and window positions coherence) using two independent synchronous operating devices. The synchronization of this device the speed of the input images.

Thus, the problem to which the present invention is directed, is to develop a method of obtaining images of an object using optical low-coherence radiation and device for its implementation, as well as devices delivering low-coherence optical radiation, which is part of the device for receiving the object image with improved performance characteristics that enable you to generate undistorted, a flat image of a flat object of study. Another challenge is to improve the transverse resolution method of obtaining images of an object that implements its devices, and delivering low-coherence optical radiation.

The essence of the developed method of obtaining images of the object lies in the fact that as well as in the way that is the closest analog, low-coherence optical radiation is directed simultaneously to the object under examination and the reference path. These optical radiation directed to the object under examination through an optical system, which provides focusing of low-coherence optical radiation to the object being tested, while the cross is the Korean people's army on the surface of the transverse scan, approximately orthogonal to the direction of propagation mentioned optical radiation. Then mix the radiation returning from the test object, and the radiation passed through the reference optical path, and display the intensity of the optical radiation returning from the test object using optical radiation, which is the result of this blending.

New in the developed method is that correct associated with transverse scanning aberration of the optical path length low-coherence optical radiation directed to the object under examination by the permanence time of propagation of low-coherence optical radiation from the distal end of the optical fiber to a corresponding conjugate point in the plane of its image while moving the distal end of the optical fiber on the specified surface transverse scan.

Suitable for the specified coordinates on the surface of the cross-scan can also longitudinal scanning, changing according to a given law, the difference between the optical lengths of the paths for the low-coherence optical radiation directed to item case, the difference between the optical lengths of the paths for the low-coherence optical radiation, directed to the object under examination, and low-coherence optical radiation directed to a reference path, modify, at least several tens of wavelengths of low-coherence optical radiation.

In another particular case, the change in the difference between the optical lengths of the paths for the low-coherence optical radiation directed to the object under examination, and low-coherence optical radiation directed to a reference path, is carried out by changing the optical path length for the low-coherence optical radiation from the surface transverse to optical scanning system.

In another particular case, the object is a biological tissue of a living organism.

In a particular implementation of this particular case the object is an internal cavity of a living organism.

In a particular implementation as mentioned low-coherence optical radiation using optical emission of visible or near-IR wavelength range.

The essence of the developed device to obtain an image of the object is that it is the same as the device that is the closest analog that contains optically coupled, istochniki associated with the processing unit and display. The interferometer includes an optical related svetorasseivateley, the measuring and reference arms, and measuring the shoulder provided with a device for delivering low-coherence optical radiation. The delivery device includes optically coupled to the optical fiber and the optical system, and a system of transverse scanning low-coherence optical radiation. The optical fiber is placed with the possibility of passing through low-coherence optical radiation from the proximal end of the delivery device to its distal end, and an optical system provides focusing of low-coherence optical radiation to the object of investigation. The optical system includes at least a first lens component with positive refractive power, and the optical fiber is part of the system transverse scan, which is configured to move the distal end of the optical fiber on the surface of the cross-scan direction approximately perpendicular to the axis of the optical fiber.

New developed device to obtain an image of the object is that the optical fiber probe done the and the distal part of the optical fiber on the specified surface transverse scan. These optical system includes at least a second lens component with positive refractive power, installed for the first-mentioned lens component.

In the particular case of surface transverse scan is characterized by a non-zero curvature.

In a particular implementation of this particular case mentioned optical fiber performs the function of elastic console and secured to the support element that is part of a fiber optic probe.

In another particular case, the first and second lens components of the optical system is placed approximately confocal.

In another particular case, the first lens component of the optical system is placed at a distance approximately equal to the focal length of this lens component, the surface of the transverse scanning, and the distance between the first and second lens components of the optical system is different from the distance corresponding to the confocal arrangement mentioned lens component of the optical system by the value of1associated with focal length F1the first lens component of the optical system and the radius R of curvature of the surface on the>sub>(F1)2/R.

In another particular case, the first lens component of the optical system is shifted to a distance of2from the position at which the distance from the lens component to the surface of the transverse scan is approximately equal to the focal length of this lens component, and the distance between the first and second lens components of the optical system is different from the distance corresponding to the confocal arrangement mentioned lens component of the optical system by the value of3defined value:

3(F1)2/(R+2).

In another particular case, the device delivering low-coherence optical radiation is made in the form of a fiber optic probe.

In another particular case, at least one of the interferometer arms is further provided with a device for longitudinal scanning of the test object.

In a particular implementation of this particular case, the device for longitudinal scanning placed in the measuring arm of the interferometer and the imp is animowane to the optical system.

In the particular case of this particular implementation upon receipt of the image the subsurface part of the investigated object coefficient M of the magnification of the optical system associated with the index of N1the refractive index of the investigated object in the following way: M=1/N1.

In the private another case of this particular implementation upon receipt of the profile image of the examined object, the coefficient M of the magnification of the optical system associated with the index of N2of refraction of the medium in contact with the surface of the investigated object, as follows: M=1/N2.

In another specific implementation of the device for longitudinal scanning placed inside the device delivering low-coherence optical radiation.

In another particular case, the distal end of the optical fiber provided with a rigidly bonded with him microlens.

The essence of the developed device delivering low-coherence optical radiation is that it as well as the delivery device, which is the closest analogue that contains optically coupled to the optical fiber placed with the possibility of passing through low-coherence optical radiation from the proximal end of the delivery device of the radiation on the object of investigation. The optical system includes at least a first lens component with positive refractive power, and a system of transverse scanning low-coherence optical radiation. Optical fiber is part of the system transverse scan, which is configured to move the distal end of the optical fiber on the surface of the cross-scan direction approximately perpendicular to the axis of the optical fiber.

New developed device delivering low-coherence optical radiation is that mentioned optical system is configured to correct aberration of the optical path length low-coherence optical radiation passing through the delivery device associated with the movement of the distal end of the optical fiber on the specified surface transverse scan. When this optical system includes at least a second lens component with positive refractive power, which is mentioned for the first lens component.

In the particular case of surface transverse scan is characterized by a non-zero curvature.

In particular realisation element, part of a device delivering low-coherence optical radiation.

In another particular case, the first and second lens components of the optical system is placed approximately confocal.

In another particular case, the first lens component of the optical system is placed at a distance approximately equal to the focal length of this lens component, the surface of the transverse scanning, and the distance between the first and second lens components of the optical system is different from the distance corresponding to the confocal arrangement mentioned lens component of the optical system by the value of1associated with focal length F1the first lens component of the optical system and the radius R of curvature of the surface cross-scan ratio:

1(F1)2/R.

In another particular case, the first lens component of the optical system is shifted to a distance of2from the position at which the distance from the lens component to the surface of the transverse scan is approximately equal to the optical system differs from the distance, the corresponding confocal location mentioned lens component of the optical system by the value of3defined value:

3(F1)2/(R+2).

In another particular case, the device delivering low-coherence optical radiation is made in the form of a fiber optic probe, while the optical fiber, the optical system and the transverse scanning low-coherence optical radiation is placed in the elongated body provided with a longitudinal through hole, in which the longitudinal direction is placed above mentioned optical fiber.

In another particular case near the image plane of the distal end of the optical fiber placed the output devices window, delivering low-coherence optical radiation. In a particular implementation of this particular case the function of the output window of the device delivering low-coherence optical radiation performs a second lens component of the optical system.

In another specific implementation of this particular case the normal to the outer surface o the of the fall of the low-coherence optical radiation at the said outer surface, greater than the angle of divergence mentioned low-coherence optical radiation at its intersection with the said outer surface.

In the particular case when the axis is approximately linear path transverse scanning of the second lens component is shifted in the direction orthogonal to the scanning direction of the cross, and in the direction orthogonal to the direction of propagation of low-coherence optical radiation.

In another particular case, the delivery device is further provided with a device for longitudinal scanning is performed with a device for changing the optical path length low-coherence optical radiation from the surface transverse to optical scanning system.

In a particular implementation of this particular case upon receipt of an image of the subsurface part of the investigated object coefficient M of the magnification of the optical system associated with the index of N1the refractive index of the investigated object in the following way: M=1/N1.

In another specific implementation of this particular case upon receipt of the profile image of the examined object, the coefficient M of the magnification of the optical system associated with the index of N2p is ω the particular case of the distal end of the optical fiber provided with a rigidly bonded with him microlens.

In the present invention, when the image of the object provided with the persistence time distribution of low-coherence optical radiation from the distal end of the optical fiber to a corresponding conjugate point in the plane of its image while moving the distal end of the optical fiber on the specified surface transverse scan. This provides a correction associated with the cross-scan aberration of the optical path length low-coherence optical radiation directed to the object under examination, and is achieved by performing the optical system in the form of at least two, placed approximately confocal, lens component with positive refractive power. In this case, as when a flat surface transverse scanning, and when the surface of the transverse scanning with the curvature of the first lens component can be installed at a distance equal to the focal distance of the component from the surface of the cross-scan and in the distance, a few more or a few less of the specified focal length. When the surface of the cross-scan has a curvature compensation include the Roma, implementation of longitudinal scanning by changing the optical path length for the low-coherence optical radiation from the surface transverse to optical scanning systems, and hence to the studied object, provides the corresponding offset where you want to focus low-coherence optical radiation for longitudinal scanning of the test object. Joint implementation of the present invention persistence time distribution of low-coherence optical radiation from a given point on the surface of the cross-scan corresponding to a conjugate point in the image plane and the specified method longitudinal scan allows you to combine the position where you want to focus low-coherence optical radiation and the position of the window of coherence, and therefore, their simultaneous movement. This eliminates the need for additional synchronization devices required in the known technical solutions. This implementation provides high lateral resolution of the method and device for its realization. Orientation normal to the outer surface of the output window of the fiber optic probe at an angle to napravlennosti low-coherence optical radiation at its intersection with the said outer surface, prevents the ingress of the reflected radiation back into the optical fiber. The specific types and forms of implementation of the second lens component characterize the invention in private specific cases of its implementation.

All the above allows to solve the problem, the solution of which the present invention is directed to develop a method for obtaining images of the object, the device for carrying and delivering low-coherence optical radiation, which is part of the unit to obtain an image of the object that allow you to create undistorted, a flat image of a flat object of study, and are also characterized by a high transverse resolution.

In Fig.1 shows a variant of the structural scheme of the developed device to obtain an image of the object, which can be implemented by a method.

In Fig.2 shows a variant of construction of the fiber optic probe (cross-section).

Fig.3, 4, 5, 6, 7 depicted embodiments of the optical system of optical fiber probe (cross-section).

Fig.8, 9, 10 illustrate the construction of the image with the known technical solutions.

Fig.11, 12, 13, 14, 15 illustrate procedury object, with the help of the developed technical solutions.

In Fig.16 shows another variant of the structural scheme of the developed device to obtain an image of the object, which can be implemented by a method.

Fig.17, 18 illustrate various embodiments of the fiber tip during placement of the device for longitudinal scanning of the examined object is made in the form of a device for changing the optical path length low-coherence optical radiation from the distal end of the optical fiber to the optical system.

In Fig.19, 20 show examples of images obtained using the well-known and developed technical solutions, respectively.

A method of obtaining images of the object, the device for carrying and delivering low-coherence optical radiation are illustrated through fiber-optic interferometer, is included in the device for optical low-coherence tomography, and optical fiber probe, although it is obvious that they can be implemented using optical elements with lumped parameters.

The device according to Fig.1 contains the associated optical source 1 low is amnic 3, the output of which is connected with the processing unit 4 and display. The interferometer 2, which in a particular implementation is a Michelson interferometer that includes optically linked svetorasseivateley 5, fiber optic measuring the shoulder 6 and the reference shoulder 7. Measuring shoulder 6 provided with a device for delivering low-coherence optical radiation, made in the specific implementation in the form of a fiber probe 8, and at the end of the reference shoulder 7 in the specific implementation of the set of the reference mirror 9. Reference the shoulder 7 contains a device 10 for longitudinal scanning of the investigated object 11. The device 10 is connected with a source of control voltage (not shown), and the output unit 4 fiber interferometer 2 is the output of the developed device.

The optical fiber probe 8 in Fig.2 contains extensive body 12, provided with a longitudinal through hole 13, in which the longitudinal direction is placed optical fiber 14, optical system 15 and 16 of the transverse scan, which is connected with a source of control current (not shown). The end face 17 of the distal portion 18 of the optical fiber 14 is optically connected with the optical system 15. Optical SCA system 15 contains, at least two lens component with positive refractive power. In a specific implementation according to Fig.2 optical system 15 includes sequentially installed on the optical axis of the first lens component 19 and the second lens component 20. 16 cross-scan made with the possibility of moving the distal portion 18 of the optical fiber 14 in a direction approximately perpendicular to the axis of the optical fiber 14. In the specific implementation shown in Fig.2, the optical fiber 14 performs the function of elastic console and secured to the support element 21 that is part of a fiber optic probe 8.

In a variant of the fiber optic probe shown in Fig.2, near the plane 22 of the image of the end face 17 of the distal portion 18 of the optical fiber 14 posted by exit window 23 of the optical fiber probe 8. The function of the output window 23 of the optical fiber probe 8 performs a second lens component 20 of the optical system 15.

A variant of the optical system 15 of the fiber optic probe 8, shown in Fig.3, does not contain the output window 23.

In the variant of the optical system 15 in Fig.4 the normal 24 to the outer surface 25 of the output window 23 of the optical fiber probe 8 is oriented at an angle2divergence mentioned low-coherence optical radiation at its intersection with the outer surface 25. In this embodiment, the second lens component 20 is displaced in the direction orthogonal to the scanning direction of the cross, and in the direction orthogonal to the direction of propagation of low-coherence optical radiation. In this particular implementation of the second lens component 20 is made in the form of a spherical lens, so the offset is implemented by the shift of the center of curvature of the lens.

Fig.5 illustrates another variant of the specified offset of the second lens component 20. It also runs the above condition the orientation of the normal 24 to the direction of the low-coherence optical radiation to the outer surface 25 of the output window 23. In this implementation, the output window 23 is made in the form of plane-parallel plates 26.

In Fig.6 shows an implementation of the optical system 15, in which the second lens component 20 performs the function of the output window 23, while the outer surface 25 of the lens component 20 is bevelled to perform the above conditions relating to the orientation of the normal 24 to the direction of the PA is redstavlena in Fig.7, the optical system 15 is made in the form of a composite lens 27, which includes the first 19 and second 20 of the lens components.

Fig.8 illustrates the construction of the image in a known manner in the known devices for the flat surface 28 of the transverse scan in the case where the optical system 29 is made in the form of a single lens component 30 with positive optical power. The drawing shows also the line 31 corresponding to the geometric place of the points, to which the optical path length of the low-coherence optical radiation directed to the object under examination 11, has the same value when the distribution from the corresponding conjugate points on a flat surface 28 of the transverse scan, different remote from the optical axis of the device.

Fig.9 and Fig.10 illustrate the construction of the image in a known manner in the known devices for the flat surface 28 of the transverse scan in cases where the optical system 29 is made in the form of two lens component 32, 33 with a positive optical power, and spaced from each other at a distance, respectively, larger and smaller confocal. In Fig.9, 10 are also shown, respectively, line 34, 35, corresponding geo is aemula on the inspected object 11, has the same value when the distribution from the corresponding conjugate points on a flat surface 28 of the transverse scan, different remote from the optical axis of the device.

Fig.11, Fig.12 and Fig.13 illustrate the construction of the image developed in the apparatus of the developed method with the flat surface 28 of the transverse scan. The first 19 and second 20 lens components located approximately confocal. Fig.11 illustrates the case when the first lens component 19 is placed at a distance approximately equal to the focal distance F1this component from the surface 28, Fig.12 illustrates the case when the first lens component 19 is placed at a distance of d1several larger focal length F1from the surface 28, and Fig.13, the first lens component 19 is placed at a distance of d2several smaller focal length F1from the surface 28. In Fig.11, 12, 13 are also shown, respectively, lines 36, 37, 38, corresponding to the geometric place of the points, to which the optical path length of the low-coherence optical radiation directed to the object under examination 11, has the same value when the distribution from the corresponding STS.

Fig.14 and Fig.15 illustrate the construction of the image developed in the apparatus of the developed method with the surface 39 of the cross-scan having a curvature R. In this Fig.14 illustrates the case when the first lens component 19 is placed at a distance approximately equal to the focal distance F1this component from the surface 39 of the transverse scan; in this case, the distance between the first 19 and second 20 of the lens components of the optical system 15 is different from the distance corresponding to the confocal arrangement mentioned lens component of the optical system 15 by the value of1associated with focal length F1the first lens component 19 and the radius R of curvature of the surface 39 of the cross-scan ratio:

1(F1)2/R.

A of Fig.15 illustrates the case when the first lens component 19 is shifted to a distance of2from the position at which the distance from the lens component 19 to the surface 39 of the transverse scan is approximately equal to the focal length F1etsa distance, the corresponding confocal location mentioned lens component of the optical system 15 by the value of3defined value:

3(F1)2/(R+2).

In Fig.14, 15 also shows the line 40 corresponding to the geometric place of the points, to which the optical path length of the low-coherence optical radiation directed to the object under examination 11, has the same value when the distribution from the corresponding conjugate points on the surface 39 of the transverse scan, different remote from the optical axis of the device.

In the device according to Fig.16, the device 10 for longitudinal scanning of the investigated object 11 placed inside the optical fiber probe 8.

Fig.17 and 18 illustrate embodiments of the optical fiber probe 8 when the device 10 for longitudinal scanning of the investigated object 11, made in the form of a device for changing the optical path length low-coherence optical radiation from the surface 28 of the transverse scan, the spatial position of which corresponds to the spaces is 17, the device 10 is connected with the distal part 18 of the optical fiber 14, and in the implementation of Fig.18 fiber optic probe 8 is further provided with mirrors 41, 42, the device 10 is connected to the mirror 42.

In Fig.17, 18 also shows the line 43 corresponding to the geometric place of the points, to which the optical path length of the low-coherence optical radiation directed to the object under examination 11, has the same value when the distribution from the corresponding conjugate points on the surface 28 of the transverse scan, different remote from the optical axis of the device.

In implementations, corresponding to Fig.17, 18, when receiving image the subsurface part of the investigated object coefficient M of the magnification of the optical system 15 is connected with the index of N1the refractive index of the investigated object 11 as follows: M=1/N1and upon receipt of the profile image of the examined object, the coefficient M of the magnification of the optical system 15 is connected with the index of N2of refraction of the medium in contact with the surface of the investigated object 11, as follows: M=1/N2.

In implementations, corresponding to Fig.17, 18, the end face 17 of the distal portion 18 of the optical fiber 14 may be provided with a rigidly bonded with him a microlens (not shown).

Source 1 preds; source 1 can be used, for example, laser or superluminescent diode.

As the interferometer 2 can be used in the interferometer of any type, for example, a Michelson interferometer, the interferometer of Mach-Zehnder interferometers, as well as combinations of such interferometers are known, in particular, on the international application number WO 00/16034.

As the photodetector 3 can be used for the photodiode.

Unit 4 is designed to generate images of the examined object by displaying the intensity of the back-scattered coherent radiation and can be performed, for example, similarly to the processing unit and display on Art. C. M. Helicon and other "Coherent optical tomography microinhomogeneities of biological tissues". JETP letters, vol. 61, vol.2, S. 149-153, which includes the serially connected band-pass filter, a logarithmic amplifier, peak detector, an analog-to-digital Converter and a computer.

The device 10 is intended for changing the difference between the optical lengths of the interferometer arms 2, i.e., for longitudinal scanning of the investigated object 11. In the implementation of the device according to Fig.1 the reference mirror 9 is stationary, and the device 10 made according to the patent of Russian Federation № 2100787 in VIII element, made with the possibility of formation in an electric field and high inverse piezo-effect, rigidly bonded to the piezoelectric element electrodes, and the optical fiber is firmly attached to electrodes. The size of the piezoelectric element in a direction approximately orthogonal to the vector of the electric field substantially exceeds the size of the piezoelectric element in a direction approximately coinciding with the vector of the electric field, the length of the optical fiber is substantially greater than the diameter of the piezoelectric element.

The device 10 can be performed similar to the scanners described in U.S. Pat. U.S. No. 5321501. In this case, the reference mirror 9 is arranged to move with constant speed, and the device 10, is connected to the reference mirror 9 may be made in the form of various mechanisms described in the mentioned patent, which required moving the reference mirror 9.

The device 10 may also be performed by senior K. F. Kwong, D. Yankelevich et al., 400-Hz mechanical scanning optical delay line, Optics Letters, Vol.18, No. 7, April 1, 1993, in the form of a dispersion-lattice delay line.

As the optical fiber 14 tselesoobraznee fiber type PANDA.

The housing 12 of the optical fiber probe 8 may be made of stainless steel.

As the first 19 and second 20 of the lens components can be made in the form of a gradient lens. The optical system 15 of the fiber optic probe 8 can also be made in the form of gradient lenses, which includes the first 19 and second 20 lens components (not shown). As the first 19 and second 20 of lens components in various specific implementations, the optical system 15 can be made in the form of a composite lens. These options are not represented on the drawings.

16 cross-scan may be performed, for example, as in the device according to U.S. Pat. Of the Russian Federation No. 2148378.

The first 19 and second 20 of the lens components may include various optical elements, which is required for correction of the various aberrations of nature. It is advisable to improve the quality of the obtained image to perform the first 19 and second 20 lens aspherical components.

In all embodiments of the fiber optic probe 8, the distance between the second lens component 20 and the plane 22 of the image is determined by the condition to ensure the focus on her low-coherence optical radiation guide is flexible and entered into the instrument channel of the endoscope (not shown). The optical fiber probe 8 can be made small (see Fig.2) and placed in the distal end of the instrument channel of the endoscope (not shown). In a specific implementation, designed for endoscopic research, the length of the body 12 does not exceed 27 mm, and its diameter does not exceed 2.7 mm

The measuring part of the shoulder 6 of the interferometer 2, comprising part introduced into the instrument channel of the endoscope, may be made removable and is connected with the main part of the measuring shoulder 6 by means of detachable connections. When the removable part of the measuring shoulder 6 of the interferometer 2 can be made disposable. For convenience, the distal portion of the optical fiber probe 8 may be made in the form of replaceable tips.

During the implementation of the developed device to obtain an image of the object according to Fig.16, the device 10 can be performed similar to the scanners described in U.S. Pat. U.S. No. 5321501. In the implementation according to Fig.16 the reference mirror 9 is stationary, and the device 10, United either with the distal part 18 of the optical fiber 14 (Fig.17), or with a mirror 42 (Fig.18) may be made in the form of various mechanisms described in the mentioned patent, providing the essential amenities to obtain an image of the object and the device delivering low-coherence optical radiation, made in the specific implementation in the form of a fiber optic probe, will be understood from the following description of the method of obtaining images of the object.

A method of obtaining images of an object using a device block diagram is shown in Fig.1, and using the fiber optic probe is shown in Fig.2, variations of the optical system shown in Fig.3-7, is implemented as follows.

Place the optical fiber probe 8 so that provided a focusing of low-coherence optical radiation to the object of investigation 11.

In a specific implementation, when the optical fiber probe 8 is an endoscopic fiber optic probe 8 is placed so that the outer surface 25 of the output window 23 is in contact with the object 11.

Low-coherence optical radiation in a specific implementation, the visible or near IR range, generated from the source 1, are sent simultaneously on the investigated object 11 and the reference path. For this low-coherence optical radiation is divided into two parts by using svetorasseivateley 5 fiber interferometer 2. Part of the optical radiation through a segment of the optical fiber 14 is on shoulder 6 and the optical fiber probe 8 of the interferometer 2 is directed to the object under examination 11. When this exercise transverse scanning this part of the optical radiation by moving the distal portion 18 of the optical fiber 14 in a direction approximately perpendicular to the axis of the optical fiber 14 by the system 16 of the transverse scan. The optical system 15 provides the focus of this part of the optical radiation on the examined object 11.

Another part of the low-coherence optical radiation directed along a reference optical path for the reference mirror 9 with reference to the shoulder 7 of the fiber optic interferometer 2. With the help of the device 10 to the specified coordinates on the surface 28 or 39 of the transverse scanning optionally change the difference in optical lengths of the shoulders 6, 7 of the interferometer 2 with constant speed V, thereby altering the given law, the difference between the optical lengths of the paths for the low-coherence optical radiation directed to the object under examination 11 and the low-coherence optical radiation directed to a reference path.

Using svetorasseivateley 5 mixed optical radiation returning from the test object 11, and the radiation passed through the reference optical path, in a particular implementation, reflected from the Ref who enzinna the intensity modulated at the Doppler frequency f=2V/where- working wavelength of the source 1, the mixed optical radiation output of svetorasseivateley 5, and the law of the interference modulation corresponds to a change in the intensity of optical radiation returning from the test object 11. Then get the image of the examined object 11 by displaying the intensity of the optical radiation returning from the test object 11, using the signal of interference modulation of the intensity of optical radiation, which is the result of this mixing, as follows.

The sensor 3 converts the mixed optical radiation from the output of svetorasseivateley 5 into an electrical signal, which is passed to the block 4. Band-pass filter unit 4 selects the signal at the Doppler frequency, which provides improved signal to noise. After amplification the signal is sent to an amplitude detector that produces a signal proportional to the envelope of this signal. The selected amplitude detector unit 4 a signal proportional to the signal of interference modulation of the intensity of the mixed optical radiation. Analog-to-digital Converter bacbacbacbac an image obtained by displaying on the display intensity of the digital signal (specified mapping can be implemented, for example, in the book. H. E. Burdick. Digital imaging: Theory and Applications, 304 pp., Mc Graw Hill, 1997). Because the digital signal corresponds to a change in the intensity of optical radiation returning from the test object 11, the resulting display image corresponds to the image of the examined object 11.

In Fig.11, 12, 13 shows a construction of an image using the developed technical solutions for the flat surface 28 of the transverse scan. From the drawings it is seen that at approximately confocal location of the first 19 and second 20 lens component of the optical system 15 lines 36, 37, 38, corresponding to the geometric place of the points, to which the optical path length of the low-coherence optical radiation directed to the object under examination 11, has the same value when the distribution from the corresponding conjugate points on a flat surface 28 of the transverse scan, different remote from the optical axis of the device, have no curvature. And this is true when placing the lens component 19 in the distance as approximately equal to the focal distance F1this component from the surface 28 and at a distance of d1greater than or at a distance of d2smaller focal distance is 38 is shifted in one direction or another relative to the location of the line 36 by a certain amount4.

In Fig.14 and 15 shows the construction of an image using the developed technical solutions for surface 39 of the transverse scan, having the curvature R Of the drawings it is seen that the line 40 corresponding to the geometric place of the points to which the optical path length of the low-coherence optical radiation directed to the object under examination 11, has the same value when the distribution from the corresponding conjugate points on the surface 39, various remote from the optical axis of the device, have no curvature. When performing the above conditions relative position of the first 19 and second 20 lens component in the absence of the curvature of the line takes place when placing the lens component 19 in the distance as approximately equal to the focal distance F1this component from the surface 39, and at a distance greater or lesser focal length F1from the surface 39.

A method of obtaining images of an object using a device block diagram is shown in Fig.16, is this the same as using the device according to Fig.1. The only difference is that the change in the difference between the optical lengths of the paths for the low-coherence optical radiation is parentname path, carried out by changing the optical path length for the low-coherence optical radiation from the surface of the cross-scan 28, i.e., from the end 17 of the distal portion 18 of the optical fiber 14 to the optical system 15, i.e. to the studied object 11. In the implementation according to Fig.17 this change the difference in optical lengths of the paths is ensured by corresponding movement of the distal portion 18 of the optical fiber 14 by means of a scanning device 10, and in the implementation of Fig.18 by corresponding movement of the mirror 42 by means of a scanning device 10. In Fig.17, 18 shows that the line 43 corresponding to the geometric place of the points, to which the optical path length of the low-coherence optical radiation directed to the object under examination 11, has the same value when the distribution from the corresponding conjugate points on the surface 28 of the transverse scan, different remote from the optical axis of the device, have no curvature. Thus the spatial position of the line 43, i.e. where you want to focus optical radiation coincides with the spatial position of the window coherence and the spatial coincidence of these provisions is maintained under longitudinal the decision, which is not distorted as a result of aberration, in contrast to images produced using known technical solutions (Fig.19).

Claims

1. The method of obtaining images of the object on which the low-coherence optical radiation is directed simultaneously to the object under examination and the reference optical path, these optical radiation directed to the object under examination using an optical fiber through the optical system, which provides focusing of low-coherence optical radiation to the object being tested, while the cross-mentioned scanning optical radiation by moving the distal end of the optical fiber on the surface of the transverse scan, approximately orthogonal to the direction of propagation mentioned optical radiation, then mixed optical radiation returning from the test object, and the radiation passed through the reference optical path, and display the intensity of optical radiation, returning from the test object using optical radiation, which is the result of this mixing, characterized in pricescope radiation, directed to the object under examination by the permanence time of propagation of low-coherence optical radiation from the distal end of the optical fiber to a corresponding conjugate point in the plane of its image while moving the distal end of the optical fiber on the specified surface transverse scan.

2. The method of obtaining images of the object under item 1, characterized in that for the given coordinates on the surface of the transverse scan additionally perform longitudinal scanning, changing according to a given law, the difference between the optical lengths of the paths for the low-coherence optical radiation directed to the object under examination, and low-coherence optical radiation directed to a reference path.

3. The method of obtaining images of the object under item 2, characterized in that the difference between the optical lengths of the paths for the low-coherence optical radiation directed to the object under examination, and low-coherence optical radiation directed to a reference path, a change of at least several tens of wavelengths of low-coherence optical radiation.

4. The method of obtaining images of the object under item 2 or 3, directed to the object under examination, and low-coherence optical radiation directed to a reference path, is carried out by changing the optical path length for the low-coherence optical radiation from the surface transverse to optical scanning system.

5. The method of obtaining images of the object under item 1, or 2, or 3, or 4, characterized in that the object is a biological tissue of a living organism.

6. The method of obtaining images of the object under item 3, wherein the object is an internal cavity of a living organism.

7. The method of obtaining images of the object under item 1 or 2 or 3 or 4 or 5 or 6, characterized in that, as mentioned low-coherence optical radiation using optical emission of visible or near infrared wavelength range.

8. Device for obtaining images of the object containing optically coupled to the source of low-coherence optical radiation, an interferometer, and at least one photodetector, the output of which is connected with the processing unit and display unit, the interferometer includes an optical related svetorasseivateley, the measuring and reference arms, and measuring the shoulder provided with a device, azedenkae with the possibility of passing through low-coherence optical radiation from the proximal end of the said delivery device to its distal end, and the optical system, which provides focusing of low-coherence optical radiation to the object under consideration and includes at least a first lens component with positive refractive power, and a system of transverse scanning low-coherence optical radiation, while the optical fiber is part of the system transverse scan, which is arranged to move the end surface of the distal portion of the optical fiber on the surface of the cross-scan direction approximately perpendicular to the axis of the optical fiber, characterized in that the device delivering low-coherence optical radiation is configured to correct aberration of the optical length measuring shoulder associated with the movement of the distal end of the optical fiber on the specified surface transverse scan, while mentioned optical system includes at least a second lens component with positive refractive power, and under item 8, characterized in that the surface of the cross scan is characterized by a non-zero curvature.

10. Device for obtaining images of the object under item 9, characterized in that the said optical fiber performs the function of elastic console and secured to the support element that is part of the device delivering low-coherence optical radiation.

11. Device for obtaining images of the object under item 8, or 9, or 10, characterized in that the first and second lens components of the optical system is placed approximately confocal.

12. A device for receiving image under item 9 or 10, characterized in that the first lens component of the optical system is placed at a distance approximately equal to the focal length of this lens component, the surface of the transverse scanning, and the distance between the first and second lens components of the optical system is different from the distance corresponding to the confocal arrangement mentioned lens component of the optical system by the value of1associated with focal length F1the first lens component of the optical system and the radius R of curvature of the bottom surface is (F1)2/R.

13. A device for receiving image under item 9 or 10, characterized in that the first lens component of the optical system is shifted to a distance of2from the position at which the distance from the lens component to the surface of the transverse scan is approximately equal to the focal length of this lens component, and the distance between the first and second lens components of the optical system is different from the distance corresponding to the confocal arrangement mentioned lens component of the optical system by the value of3defined by a relation3(F1)2/(R+2).

14. Device for obtaining images of the object under item 8, or 9, or 10, or 11, or 12, or 13, characterized in that the device is delivering low-coherence optical radiation is made in the form of a fiber optic probe.

15. Device for obtaining images of the object under item 8, or 9, or 10, or 11, or 12, or 13, or 14, characterized in that at least one of the interferometer arms is further provided with a device that the device for longitudinal scanning placed in the measuring arm of the interferometer and made providing the change of the optical length measuring from shoulder surface transverse to optical scanning system.

17. Device for obtaining images of the object under item 16, characterized in that when receiving images of the subsurface part of the investigated object coefficient M of the magnification of the optical system associated with the index of N1the refractive index of the investigated object in the following way: M=l/N1.

18. Device for obtaining images of the object under item 16, wherein upon receipt of the profile image of the examined object, the coefficient M of the magnification of the optical system associated with the index of N2of refraction of the medium in contact with the surface of the investigated object, as follows: M=1/N2.

19. Device for obtaining images of the object under item 15, or 16, or 17, or 18, characterized in that the device for longitudinal scanning placed inside the device delivering low-coherence optical radiation.

20. Device for obtaining images of the object under item 16, or 17, or 18, or 19, characterized in that the end surface of the optical fiber provided with a rigidly bonded with him microlens.

21. The device delivering low-coherence optical radiation containing optically coupled to the optical fiber placed with passing through it discotecas system, which provides focusing of low-coherence optical radiation to the object under consideration and includes at least a first lens component with positive refractive power, and a system of transverse scanning low-coherence optical radiation, while the optical fiber is part of the system transverse scan, which is arranged to move the end surface of the distal portion of the optical fiber on the surface of the cross-scan direction approximately perpendicular to the axis of the optical fiber, characterized in that the said optical system is configured to correct aberration of the optical path length low-coherence optical radiation passing through the delivery device, associated with movement of the distal end of the optical fiber on the specified surface transverse scan, when this optical system includes at least a second lens component with positive refractive power, which is mentioned for the first lens component.

22. The device delivering low-coherence optical radiation on p. 21, characterized in that the surface p is nnogo optical radiation on p. 22, characterized in that the said optical fiber performs the function of elastic console and secured to the support element that is part of the device delivering low-coherence optical radiation.

24. The device delivering low-coherence optical radiation on p. 21, or 22, or 23, characterized in that the first and second lens components of the optical system is placed approximately confocal.

25. The device delivering low-coherence optical radiation under item 22 or 23, characterized in that the first lens component of the optical system is placed at a distance approximately equal to the focal length of this lens component, the surface of the transverse scanning, and the distance between the first and second lens components of the optical system is different from the distance corresponding to the confocal arrangement mentioned lens component of the optical system by the value of1associated with focal length F1the first lens component of the optical system and the radius R of curvature of the surface cross-scan ratio1(F1), the first lens component of the optical system is shifted to a distance of2from the position at which the distance from the lens component to the surface of the transverse scan is approximately equal to the focal length of this lens component, and the distance between the first and second lens components of the optical system is different from the distance corresponding to the confocal arrangement mentioned lens component of the optical system by the value of3defined by a relation3(F1)2/(R+2).

27. The device delivering low-coherence optical radiation on p. 21, or 22, or 23, or 24, or 25, or 26, characterized in that the device is delivering low-coherence optical radiation is made in the form of a fiber optic probe, while the optical fiber, the optical system and the transverse scanning low-coherence optical radiation is placed in the elongated body provided with a longitudinal through hole, in which the longitudinal direction is placed above mentioned optical fiber.

28. The device delivering low-coherence optical radiation under item 21 or 22, the ical fiber placed the output devices window, delivering low-coherence optical radiation.

29. The device delivering low-coherence optical radiation on p. 28, characterized in that the function of the output window of the device delivering low-coherence optical radiation performs a second lens component of the optical system.

30. The device delivering low-coherence optical radiation under item 28 or 29, characterized in that the normal to the outer surface of the output window of the device delivering low-coherence optical radiation is oriented at an angle to the direction of the low-coherence optical radiation at the said outer surface is greater than the angle of divergence mentioned low-coherence optical radiation at its intersection with the said outer surface.

31. The device delivering low-coherence optical radiation on p. 30, characterized in that when axis is approximately linear path transverse scanning of the second lens component is shifted in the direction orthogonal to the scanning direction of the cross, and in the direction orthogonal to the direction of propagation of low-coherence optical radiation.

32. The device delivering low-coherence optical radiation on p. 21, or 22, or 23, or the longitudinal scan, made in the form of a device for changing the optical path length low-coherence optical radiation from the surface transverse to optical scanning system.

33. Device for obtaining images of the object under item 32, wherein when receiving images of the subsurface part of the investigated object coefficient M of the magnification of the optical system associated with the index of N1the refractive index of the investigated object in the following way: M=l/N1.

34. Device for obtaining images of the object under item 32, wherein upon receipt of the profile image of the examined object, the coefficient M of the magnification of the optical system associated with the index of N2of refraction of the medium in contact with the surface of the investigated object, as follows: M=1/N2.

35. The device delivering low-coherence optical radiation under item 21 or 22 or 23 or 24 or 25 or 26 or 27 or 28 or 29 or 30 or 31 or 32 or 33 or 34, characterized in that the distal end of the optical fiber provided with a rigidly bonded with him microlens.



 

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FIELD: methods of phase modulation.

SUBSTANCE: method is based upon applying step sawtooth voltage to wideband phase modulator. Sawtooth voltage is specified with of numbers of m, n and k. Duration of each step equals to path time of light beam along light-guide of sensitive coil of gyro used to perform modulation of phase difference of beams of ringular interferometer. It is presented in form of pulse sequence with period of T0. During first half-period of the sequence the phase difference pulses have like number of alternating pulses with amplitudes of -(π-Δ) radians and +(π+Δ) radians. During second half-period the pulses have like number of alternating pulses with amplitudes of -(π+Δ) and +(π-Δ) radians correspondingly. Values of m and n are chosen from set of any positive integer non-zero numbers. Value of Δ is chosen within range of values from 0,05π radians≤ Δ ≤0,95π radians.

EFFECT: improved sensitivity of fiber-optic gyro; improved stability of scale factor.

5 dwg

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