The interferometer to control the surface shape of a convex hyperbolic mirror

 

(57) Abstract:

Usage: for contactless control of the shape of the reflecting surface of the convex hyperbolic mirror of large diameter with Central shielding. The inventive interferometer to control the surface shape of a convex hyperbolic mirror contains the driver working and reference wavefronts, including the working and the reference branch, the reference spherical mirror placed in the working branch, the spherical aberration corrector installed in a working branch between the shaper working and reference wavefronts and reference spherical mirror site discharge of controlled mirrors. When this concealer, installed between the driver working and reference wavefronts and reference spherical mirror made of one-component, representing a plane-parallel plate coated on one surface systems holographic relief. Spherical reference mirror and the spherical aberration corrector form of the aberration compensator normal to the test surface and together with controlled hyperboloid are working branch neravnovesnogo interferometery technique and can be used for contactless control of the shape of the reflecting surface of the convex hyperbolic mirror of large diameter with Central shielding.

Known interferometer to control the surface shape of a convex hyperbolic mirror, built by the compensation scheme Hindle containing driver working and reference wavefronts, including the working and reference branches; the reference spherical mirror placed in the working branch so that its center of curvature aligned with the available focus convex hyperbolic surface controlled mirror; and the site of discharge of the controlled mirrors [1].

The advantage of this interferometer is that to control the surface shape of a convex hyperbolic mirror need only control the spherical mirror placed in the working branch of the interferometer.

The scheme allows you to control hyperboloid in a wide range of characteristics, however, mirrors, working with a large increase, equal to the ratio of focal lengths, and low coefficient of shielding, you may have a spherical mirror is too large of a diameter many times greater than the diameter of the hyperboloid), or too fast, which will make the scheme is not practically implementable, or very expensive.

Known interface, the economic mirrors introduced a system of two mirrors of the same diameter, moreover, more than three times smaller than the diameter of the control of the spherical mirrors in the above-described interferometer [2].

The undoubted advantage of this interferometer is a significant reduction in the diameters of the control spherical mirrors with a free tolerances on the absolute values of the radii of curvature.

The disadvantage of the interferometer to increase the number of optical components required to control the surface shape of a convex hyperbolic mirror. Although the exact phasing of the control of the spherical mirrors is not required, but there is the need to produce two control mirrors instead of one. Complicated operation of interferometer alignment in the process.

Overall a significant drawback of both interferometers described above is a significant length of the working branch, due to the parameters of the test surface. Available focus controlled convex hyperbolic mirror from the last several times more than available with which combined center of curvature of the control of a spherical mirror. As a consequence both of the interferometer have low vibration and omahas the ski components of the interferometer in the latter there is no continuous monitoring of their spatial and temporal stability. To avoid possible measurement errors in the manufacturing process, control and certification of convex hyperbolic mirror required periodic inspection parameters relative position of optical components, which requires complicated adjustment operations. The control of the spherical mirror must have a high aperture, which greatly complicates their manufacture by minimizing the deviations from the specified form of the surface.

Interferometer for monitoring convex hyperbolic mirror can also be built by the compensation scheme D. D. Maksutov [3]. In this case, the control is performed by means of the control mirror, which has the shape of an ellipsoid and a compensator normal to the test surface. The diameter of the control mirror is close to the diameter of the hyperboloid.

The interferometer includes only one additional element (control elliptical mirror) and is significantly less than in the above-described schemes, the length of the working branch, which improves its noise immunity.

The main disadvantages are: the ability to control only hyperboloid with small asferico the situation.

Closest to the proposed invention the technical essence is the interferometer to control the surface shape of a convex hyperbolic mirror, Susiana [4] and contains the shaper working and reference wavefronts, including the working and reference branches; mirror-lens corrector of spherical aberration, the reference spherical mirror installed in the working branch. Mirror-lens corrector forms with the reference spherical mirror aberration compensator normal to the surface of a convex hyperbolic mirror.

This interferometer has a number of advantages. Control spherical mirror has a diameter comparable to the diameter of the monitored convex hyperbolic mirror, and its curvature is less than that required in the schema Hindle. Therefore, the manufacturing of such control of a spherical mirror is easier and cheaper. In addition, the total length of the control scheme (working branch of the interferometer) is much smaller than in the case of the interferometer, Hindle.

A major and very serious disadvantage of the interferometer is a complex mirror-lens corrector. This increases the number of which is the number of possible sources of measurement error, since the parameters of the mirror-lens corrector rigidly consistent with the parameters of the test surface.

The aim of the invention is to reduce the size of the control scheme, simplify design, increase reliability and facilitate alignment of the interferometer.

This objective is achieved in that in the known interferometer containing driver support and desktop wave fronts, including the working and the reference branch, the spherical aberration corrector and a controlling spherical mirror installed in the working branch, and the site of discharge of the controlled mirror; concealer made a single component in the form of plane-parallel plates coated on one surface of the three systems holographic relief - one primary and two alignment (see Fig. 1). The basic system of the holographic relief 5 forms with the reference spherical mirror aberration compensator normal to the surface of a convex hyperbolic mirror. Additional system holographic relief are Ostrovskii; one model reflecting sphere, concentric with the point created by the shaper reference and working wavefronts in working puchkovoi the aberration compensator normal to the control surface of a spherical mirror at the same point 7 and serves to align the provisions of the control of a spherical mirror relative to the corrector and shaper (see Fig. 2). Any alignment system holographic relief can be located on the periphery of the main hologram (as shown in Fig. 2) and in Central, screened hole in the hyperbolic mirror, part of the corrector 8.

As proof can also be used PLANO-concave lens with applied systems holographic relief described above, which can significantly reduce correctional load on the main hologram and many times to reduce the number and frequency areas of the hologram.

Concealer and node unloading convex hyperbolic mirror can be collected in a single construction site.

Control spherical mirror can be made with holographic relief, and the effective radius of curvature of the hologram relief on the control spherical mirror is smaller than the radius of curvature of the spherical mirror.

The set of distinctive features of the present invention with respect to the prototype is a significant and new, because it allows for substantial technical and economic effect in the field of measuring and control equipment.

Using goal is unknown to us the fact that the joint use of the hologram element and control of a spherical mirror to achieve the objectives of the invention.

The execution of the offset one-component allows to refuse from multi-element lens / mirror corrector scheme, difficult to manufacture and align. Because of this simplified design, improved reliability of the interferometer and decrease its dimensions.

The performance of the holographic relief consisting of three systems allows you to use one of them, the principal, in conjunction with the control of a spherical mirror as the aberration compensator normals to the surface controlled convex hyperbolic mirror, and two others, to adjust the relative position of the elements of the interferometer. Alignment of the hologram greatly simplify the process of initial alignment of the interferometer, as well as provide continuous monitoring, that is, the mutual arrangement of the components of the interferometer in the process. Application of three systems holographic relief on a single surface of the corrector provides unambiguous installation of circuit elements.

Rigid connection of the compensator and the site of discharge of the controlled convex hyperbolic mirror in a single structural node allows to achieve their simple installation, stabilizer and increase its reliability.

Execution control of a spherical mirror with a holographic relief reduces the effective radius of curvature of this component and to reduce the dimensions of the interferometer (the length of the working branch).

The use of each of the above characteristics is known, but the unknown fact of their total use, which confirms the criterion of novelty of the claimed solution. And as each of the distinctive characteristics affect the role of the other and cannot be excluded without violating the overall effect of their combined use, the proposed solution meets the materiality of the differences.

The interferometer works as follows (see Fig. 1). Working wave front emerging from the shaper working and reference wavefronts 1, falls to the spherical aberration corrector 2. The working part of the wave front is reflected from one adjusting system holographic relief simulating a sphere concentric with the point created by the imaging unit 1, back in the specified driver. It is used to set the offset 2 relative to the imaging unit 1. Another part of working wavefront passes through the second alignment system holographic Rel is the part of the working of the wave front in the autocollimating course passes corrector 2 and enters the imaging unit 1. A specified part of the wave front is used for setting the control of the spherical mirror 3 with respect to the imaging unit 1 and offset 2. The interference pattern obtained by the interaction of these parts working wavefront from a reference wavefront generated by the imaging unit 1, allow not only the initial alignment of the components of the interferometer, but to constantly monitor the stability of the adjustment in real-time. The working part of the wave front that passes through the root system of a holographic relief corrector 2, is reflected from the surface of the control of the spherical mirror 3 to the normals to the surface of a convex hyperbolic mirror 4, is installed on the site of unloading. Reflected from the latter, the working wave front in the reverse course is reflected from the reference spherical mirror 3, passes through the corrector 2 and enters the imaging unit 1, which interferes with the reference wave front.

Thus, the proposed interferometer allows to reduce the dimensions of the control circuit due to the replacement of complex mirror-lens corrector for single-label and hologram relief which has a simple structure, consequently, more reliable and easy to align. System adjusting holographic relief facilitates alignment and improves the reliability of the interferometer, as it allows you to monitor the relative position of its components in the process.

Sources of information

1. AV. St. USSR N 149910.

2. A. G. Seregin, I. S. Pateman, T. N. Tuleva. To calculate the parameters of the modified scheme Hindle when the control convex hyperbolic surfaces.//WMD, 1991, No. 9, S. 83-85.

3. N. N. Michelson. Optical telescopes. Theory and design. - M.: Nauka, 1976, S. 332.

4. Jose M. Sasian. Design of null lens correctors for the testing of astronomical optics.//Opt.Eng., Vol. 27(12), pp. 1051-1056, Dec. 1988.

1. The interferometer to control the surface shape of a convex hyperbolic mirror that contains the driver working and reference wavefronts, including the working and reference branches; the reference spherical mirror placed in the working branch, the spherical aberration corrector installed in a working branch between the shaper working and reference wavefronts and reference spherical mirror site discharge of controlled mirrors, characterized in that the corrector, set linen one-component, representing a plane-parallel plate coated on one surface of the three systems holographic relief, one of which, the main forms together with the control of a spherical mirror aberration compensator normal to the test surface, and the other two, additional, serve for adjustment of the mutual position of the elements of the interferometer.

2. The interferometer under item 1, characterized in that the corrector and the site of discharge of the controlled mirror is made in the form of a single construction site.

3. The interferometer under item 1, characterized in that the control spherical mirror made with holographic relief smaller effective radius of curvature.

 

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3 cl, 2 dwg

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