The method of recording and/or reading optical information and the device for its implementation

 

(57) Abstract:

The invention relates to the field of optical instrumentation and can be used in the systems of recording and reading optical information. The method includes forming the base and the working optical channels on one side of the carrier 3; accommodation optically addressable spatial light modulator (OASLM) 7 in the plane of the exit pupil of the reference channel, conjugate with the plane of the entrance pupil of the working channel. The light beam of the reference channel is divided into two mutually coherent components, one of which is directed to ASLM 7, and the other first sent to the carrier 3, then (after its reflection from the surface of the carrier 3) directed to the OASLM and mixed with the first. This set is a definite correlation between the total longitudinal magnification of the reference and the working channels and the wavelength of the working and reference radiation. Working radiation is directed on the OASLM, towards supporting and difragirovavshej in the first order wave focus on the media. The device contains two sources 1 and 2 radiation, a beam splitter 4, the mirror system 8, the modulator 7 light (OASLM), the lens 6, the carrier 3 and the reception is whether the read information, as well as improving quality while reducing the requirements to the quality of the optical elements. 2 S. and 4 C.p. f-crystals, 1 Il.

The invention relates to the field of optical instrument, in particular to systems for recording and/or reading information on the optical memory storage devices with relative operational movement of the information carrier, and can be widely used in high-speed digital video recording devices, and external optical storage device (one-way access to information the carrier surface), requiring superprecision combining the focused recording and/or reading light beam from the light-sensitive layer of the information track of the optical memory media.

Most of the currently used methods of tracking information track of the optical media memory based on the movement of the focusing means, which (i.e., moving) must be strictly coordinated with the random change of the spatial position information of the surface of the track (during reading) or light-sensitive layers of information (in writing) of the media information about the focus with the vibration and/or technological crown of light-sensitive information layer of the information carrier.

In such cases, to increase the speed of writing/reading information by reducing the inertia of the moving of the focusing elements is necessary to reduce the weight and, consequently, the size of the focusing means, which negatively (in particular, reducing the size) affects the quality of the read/write information at high speeds of movement of the carrier in the process of information exchange. When the maximum allowable implemented at the present time, the running speed of the media (up to 10,000 revolutions per minute in the 50s MAX CD-ROM), the average rate of information sharing does not exceed 5 MB/sec.

Thus, methods based on electro-mechanical tracking and compensation of errors of focusing light beams, exhausted its possibilities in the systems used for recording and reading large volumes of information at high relative speeds of movement of the carrier and the focused light beam. For example, in devices of the optical recording/reading information on a disk media at high speeds of rotation of the carrier levels of vibrations reach values of order 4g, overheating and accelerated mechanical wear of the opto-mechanical knots the beam) with the tracks of the disk media. If there is a taking of the track, the tracking servo control, as well as focusing servo control, upset and interrupts the playback signals or produces unnatural artificial signals mentioned playback. In usual practice has to contend with the vibrations by means of mechanical protection from dynamic effects of the system.

Current CD drives include a radiation source and a kind of optical system, which focuses this radiation on the working surface of the disk. In this optical system provided by the branch portion of the reflected radiation on special sensors. There are several different ways that, for example, change astigmatism allow us to estimate the displacement of the disk in the longitudinal (i.e. along the axis of rotation) direction. This signal is further measured, amplified and used to control the position of the optical head relative to the disk surface.

Thus, the traditional approach, which is used for the focus, based on the measurement of reflected signal shift in focus relative to the information surface of the track and management (synchronize tracking system using a variation of the wavelength of the radiation. This method allows you to focus the beam directly on a given track or on a given surface.

A known method of recording and reading optical information and the device for its implementation using an electrically addressable spatial light modulator described in the patent US 5844709 (CL G 02 F 1/03, 1998 ). A disadvantage of the known method and device for its implementation are the constructive complexity of tracking information track, and the relative inertia of the system and lack of range of movement of the focus, in particular, the light beam for the tracking information track of the information carrier, due to the low spatial resolution of the aforementioned spatial light modulator.

Closest to the claimed method of recording and/or reading optical information and the device for its implementation are the method and the device described in and.with. SU 1509996 (CL G 11 In 7/08, 1987).

The known method includes focusing the primary image of the light signal in the area of the mirror surface of the reflector and the subsequent focus once reflected from the mirror surface is Oia information layer of the carrier is accomplished by the process of compensation of defocus (relative to this layer) mentioned the reflected radiation. The compensation process is carried out by moving the mirror surface of the reflector along the main optical axis of the focusing tool first components of the optical system, through which (i.e., first component) mentioned formed the primary image of the light signal.

Known from the prior art device for the implementation of the method described above) contains a reflector with a mirror surface, the radiation source and the optical system including a beam splitter, one output of which is optically connected with means for focusing the first components of the optical system with the possibility of the formation of the primary image in the area of the mirror surface of the reflector, and the second output of the beam splitter optically connected with means for focusing the second components focusing reflected from the mirror surface radiation on the information layer of the device. The reflector is provided with means for moving the mirror surface along the above-mentioned main optical axis with the possibility of compensation of defocus mentioned reflected radiation in the process of operating positions of the photosensitive informalization (implementation) is the system response time compensation of defocusing due to a synchronized (with operational changes in the spatial position of the photosensitive layer media) opto-mechanically movable elements, that entails negative consequences similar to the above.

The technical task of the invention is to provide such a method of recording and/or reading optical information, which by means of instantaneous (purely optical) tracking information track of the information carrier can improve the quality of the recording and/or reading this information, as well as simplifying the design (especially the servo tracking system) in General.

The task (in respect of the subject matter of the invention "method") is achieved by the fact that in the method of recording and/or reading optical information, including compensation of distortion in the light beam by reflection of the light beam from the reference surface, the movement of which in a certain way will coordinate with the movement of the information carrier, according to the invention, to form the reference and the working optical channels on one side of the optical information carrier; placing the optically addressable spatial light modulator in the plane of the exit pupil of the reference channel, conjugate with the plane of the entrance pupil of the working channel; separate optical radiation of the reference channel in two mutually coherente light, and the second is directed to the above-mentioned light modulator after its reflection from the reference surface of the optical information carrier, while the total longitudinal increase support and operational channel set in accordance with condition

= 0,5w/r,

where is the total longitudinal magnification of the reference and the working channels;

wthe wavelength of the reference channel;

r- wavelength radiation in the working channel,

in addition, when recording information, the optical radiation with a wavelengthrsent for optically addressable spatial light modulator, and diffracted in the first order radiation is focused on the recording layer of the optical information carrier, and when reading information on the optical media recording (information) sent a relatively narrow beam, for example, light radiation at the operating wavelengthrwhen this scattered information on the label media the radiation is directed onto an optically addressable spatial light modulator, and then difragirovavshej in the first order component of the radiation is directed to the receiver of this radiation.

In the particular case as an optically addressed the ri, forming an interference pattern on the above-mentioned optically addressed spatial modulator to produce in the near IR range, and reading and/or writing information in the working channel is produced in the visible range.

Appropriate ratio of wavelengthswandrinstall in accordance with condition w/r= 2.

The task in relation to the subject invention, the device achieved by the capture device and/or reading optical information containing the optical information carrier, at least one optical radiation source, a beam splitter, one output of which is optically connected with the optical information carrier through sequentially placed a quarter-wave plate and a lens and mirror system and the radiation detector according to the invention, further comprises a second source of optical radiation and optically addressable spatial light modulator, both the source of optical radiation functionally are respectively the sources of the working and reference radiation, and optically addressable spatial light modulator placed in the plane of the exit pupil of the reference channel, conjugate with the plane of the entrance pupil of the working channel, while supporting and working channels are located on one side of the media modulator through a system of mirrors, while the total longitudinal magnification of the reference and the working channels established in accordance with condition

= 0,5w/r,

where is the total longitudinal magnification of the reference and the working channels;

wthe wavelength of the reference channel;

r- wavelength radiation in the working channel.

In the particular case of optically addressable spatial light modulator is a PC combined with a liquid crystal screen.

It is advisable that the ratio of the wavelengthswandrwas established in accordance with conditionw/r= 2.

The invention is illustrated in the drawing, which presents a schematic diagram of one possible embodiment of the device for implementing the inventive method of recording and/or reading optical information.

The device comprises a source 1 of the working optical radiation source 2 reference optical radiation, the carrier 3 of the optical information, a beam splitter 4, one end of which is optically connected with the carrier 3 of the optical information through sequentially placed a quarter-wave plate 5 and the lens 6. In the plane of the exit pupil of the reference channel, sulator light (OASLM) 7. The second output of the beam splitter 4 is optically connected with the OASLM 7 through a system of mirrors 8. The radiation receiver not shown.

In a specific example implementation of the invention consider in detail the operation of the device and the method of recording and reading optical information.

From source 2 reference radiation direct beam of light with a wavelengthwon the beam splitter 4. One part of the beam passes through a beam splitter and reflected from the mirror system 8, falls on the OASLM 7. The other part of the beam reflected from the beam splitter 4, is sent to the carrier 3 of the optical information through a quarter-wave plate 5 and the focusing lens 6. Reflected from the mirror surface of the carrier 3, referred to another part of the light beam becomes defocusing equal to twice the displacement of the mirror surface, passes back through the lens 6, the quarter-wave plate 5, through a beam splitter 4, and simultaneously with the first part of the beam falls on the OASLM 7, interferir with her.

On the light modulator OASLM 7 is formed interference pattern at a wavelength of win the interaction of the two mentioned component, one of which, let's call it the signal carries information about the errors otkloneniya wave.

The density distribution of electric charges on the photoconductor modulator reproduces the intensity distribution of the interference pattern and, accordingly, causes a change in the optical characteristics of the LCD screen (the gradient of the refractive index modulation of the polarization properties).

The specified pattern is read using a working light wave is directed from source 1 working light on the modulator 7 toward the reference plane wave. The change in the refractive index causes difragirovavshej waves, which are fully representative of the signal wave with defects, but provided that the wavelengths of working and signal radiations are the same, i.e.r=w. Because working (healing wave) moves toward a planar reference wave, the wave front difragirovavshej waves in the first order will be to repeat the front of the signal wave. If wavelengthsrandwdo not match, the front difragirovavshej in the first order wave will be geometrically similar to the reference scale, equal to the ratio of the wavelengthsw/rand the execution ratio = 0,5w/rshifting the focus difragirovavshej beam will be in two rasarus difragirovavshej beam will always keep track of the information layer of the device 3.

Moreover, because the specified difragirovavshej (restored) the wave propagates along the same path as the signal wave, i.e., through a beam splitter 4, the plate 5 and the lens 6, but only in one direction, it is possible to partially compensate distortion of optical components. The most complete compensation can be achieved if the conditionw/r= 2. In this case, in addition to compensate for the defocusing caused by the offset of the carrier 3, will be fully compensated for the distortions caused by the aberration of the lens 6, since the signal wave twice passes the lens 6, while its distortion due to the aberration of the lens is doubled compared to difragirovavshej (restored) wave, which passes through the lens 6 once. Thus the combination of conditions = 0,5w/randw/r= 2 is perfect.

The claimed method and device allow you to focus radiation with one-sided access to the information surface of the optical information carrier (e.g., disk), which is achieved through the use of OASLM (transparency), which provides a comprehensive pair of the light wave. There exists a wide class of prostranstve the stresses and which operate at low illumination light. The most suitable modulators based ferroelectrics. Another advantage of the invention is the use of the same lens in the working and reference channels, achromatizing for wavelengthsrandw. The lens corrects for spherical aberration so that the wave spherical aberration in the reference channel at wavelengthwin the plane of the OASLM (after double-passing the wave through the lens) is equal to the wave spherical aberration at wavelength rworking channel.

In addition, the invention allows for instantaneous recording and reading of information, to reduce the requirement to the quality of optical elements and to improve the quality of the images, and also get rid of the mechanical system tracking information track.

1. The method of recording and/or reading optical information, including compensation of distortion in the light beam by reflection of the light beam from the reference surface, the movement of which in a certain way will coordinate with the movement of the information carrier, characterized in that the shape of the reference and the working optical channels on one side of the optical information carrier; placing optically addressable Ave is on the pupil of the working channel; share optical radiation of the reference channel in two mutually coherent components, one of which is directed directly onto an optically addressable spatial light modulator, and the second is directed to the above-mentioned light modulator after its reflection from the reference surface of the optical information carrier; while the total longitudinal increase support and operational channel set in accordance with condition = 0,5w/rwhere is the total longitudinal magnification of the reference and the working channels;wthe wavelength of the reference channel;r- wavelength radiation in the working channel; recording information of the optical radiation with a wavelengthrsent for optically addressable spatial light modulator, and diffracted in the first order radiation is focused on the recording layer of the optical information carrier; when reading information on the optical information carrier direct a narrow beam of light at the working wavelength rwhen this scattered information on the label media the radiation is directed onto an optically addressable spatial light modulator, and then difragirovavshej in the first order component of the radiation gamago spatial light modulator using a photoconductor, combined with LCD screen, forming an interference pattern on an optically addressed spatial modulator to produce in the near infrared range, and the reading and/or writing information in the working channel is produced in the visible range.

3. The method according to p. 1 or 2, characterized in that the ratio of the wavelengthswandrinstall in accordance with conditionw/r= 2.

4. A device for recording and/or reading optical information containing the optical information carrier, at least one optical radiation source, a beam splitter, one output of which is optically connected with the optical information carrier through sequentially placed a quarter-wave plate and a lens and mirror system and a radiation receiver, characterized in that it further comprises a second source of optical radiation and optically addressable spatial light modulator, both the source of optical radiation functionally are respectively the sources of the working and reference radiation and optically addressable spatial light modulator placed in the plane of the exit pupil of the reference channel, paired with p is osites optical information, the second output of the beam splitter is optically connected with an optically addressable spatial modulator through a system of mirrors, while the total longitudinal magnification of the reference and the working channels established in accordance with condition = 0,5w/rwhere is the total longitudinal magnification of the reference and the working channels;wthe wavelength of the reference channel; r- wavelength radiation in the working channel.

5. The device according to p. 4, characterized in that the optically addressable spatial light modulator is a PC combined with a liquid crystal screen.

6. The device under item 4 or 5, characterized in that the ratio of the wavelengthswandrinstall in accordance with conditionw/r= 2.m

 

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