SU1696931A1 - Method of interference testing of quality of telescopic optical systems - Google Patents

Abstract

The invention relates to a measuring and control technique and is intended to control the quality of telescopic optical systems. The purpose of the invention is to increase the sensitivity of the control. The method includes passing a coherent light wave through a diffuse scatterer, passing a diffusely scattered wave through a controlled telescopic optical system, registering a hologram, transmitted object wave with a reference plane wave, lighting the hologram with the same waves, registering the interferogram in the Fourier plane of the hologram and monitoring quality telescopic optical system for interferogram. New is the registration of the hologram in the plane of images of the diffuse diffuser, its illumination with waves with modified angles of incidence. Moreover, changes in the angles of incidence of the reference and object waves are equal in magnitude and opposite in direction, and prior to the registration of the interferogram, the past waves are spatially filtered in the plane of the hologram. 1 il. w ё

Description

The invention relates to a measuring and control technique, and is intended to control the quality of Kepler-type telescopes and can be used in production, which is concerned with their manufacture.

The closest in technical essence is a method of controlling the quality of the optical system of lenses, including a Kepler-type telescope, through which a coherent light wave is passed through a diffuse scatterer, a diffusely scattered wave is passed through a controlled telescopic system, and a hologram of a transmitted object wave with a reference plane is recorded wave, light

A hologram with the same waves shifts the object under control perpendicular to its optical axis and records the interferogram using a lens mounted behind the hologram.

The disadvantage of this method is low sensitivity control. This is due to the fact that in differential interferometry underlying the method, the sensitivity of the control is determined by the magnitude of the shift. Since with an increase in the shift in diffusely scattered fields, the frequency of periodic interference fringes caused by the focal lengths of the objective and the eye of the telescopic lens increases sharply.

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then this leads to a drop in the contrast of the interference pattern until it disappears because the period of the interference fringes becomes comparable with the size of the glass.

The aim of the invention is to increase the sensitivity of the control.

Pass a coherent light wave through a diffuse scatterer, pass a diffusely scattered wave through a controlled telescopic optical system, record the hologram of the transmitted object wave with the reference plane wave, illuminate the hologram with the same waves, record the interferogram in the fourier plane of the hologram and monitor the quality of the telescopic system interferogram.

In contrast to the known method, a hologram is recorded in the image plane of the diffuse scatterer and illuminated with waves with modified incidence angles, and the incidence angles of the reference and object waves are opposite in direction, before the interferogram is recorded, spatial filtering of the transmitted waves in the hologram plane is performed.

The proposed method provides the creation of conditions for obtaining a lateral shear interferogram in bands of infinite width using coherent diffusely scattered light, as a result, the sensitivity increases compared with differential interferometry in bands of finite width.

The drawing shows a diagram of the device that implements the proposed method.

The device includes a unit 1 for forming and tilting a flat wave front for illuminating a matte screen 2, a controlled object 3, a unit 4 for shaping and tilting a plane front for a reference wave and lighting a photographic plate - a hologram 5, a spatial filter 6, a lens 7, an interferogram recorder 8.

The device works as follows.

A coherent wave of a flat shape formed in block 1 is used to illuminate a matte screen 2. Using a controlled object 3 in the form of a Kepler telescope, an image of a matte screen 2 is constructed in the plane of the photographic plate 5 and a hologram 5 of a matte screen 2 is recorded on it using a reference screen waves of a flat shape formed in block 4. After the indicated recording, holograms 5 illuminate it with initial waves and change the angle of inclination

of the restoring wave from i i, at which it was recorded, to EH, and in the opposite direction, change the angle of inclination of the illumination wave of the matte screen 2 by an amount a that satisfies the relation

0 5

0 5

f2

-z- sin a - sin © i - sin 02 fi

where f 1 and fa are the focal lengths of the lens and the ocular of the telescope, respectively.

Using an opaque screen 6 with a circular hole, the center of which is on the optical axis, a correlated speckle-field is filtered out, which in the focal plane of the lens 7 form an interferogram of the lateral shear in the bands

0 infinite width characterizing the axial wave aberrations of the object under test 3. Shifting the center of the filtering diaphragm in the direction of changing the angles a and 0 within the image of a matte screen 5 by 2 leads to spatial filtering of the lateral shear interferogram characterizing the quality of the object 3 for off-axis waves by the angle field | view. Registration interference

0 pictures are carried out using an interferogram recorder 8 (film, photo detector array, etc.) located in the focal plane of the objective 7.

Claims (1)

5 claims The method of interference control of the quality of telescopic optical systems, including the transmission of a coherent light wave through a diffuse scatterer, passing a diffusely scattered wave through a controlled telescopic optical system, recording a hologram of a transmitted object wave with a reference plane wave, illuminating the hologram with the same waves, registering an interferogram in Fourier hologram planes and telescopic optical system quality control over an interferogram, characterized in that Increasing the sensitivity of the control, the hologram is recorded in the image plane of the diffuse scatterer and illuminated with waves with modified incidence angles, the changes in the angles of incidence of the reference and object waves are opposite in direction, and the difference between the sines of the angles of incidence of the waves and the hologram is equal to the product of the image conversion scale factor in the hologram plane on the sine of the angle change five the incidence of waves on the diffuse scatterer, prior to recording the interferogram, the past waves are spatially filtered in the hologram plane.