SU1577942A1 - Method of working surfaces of optical components - Google Patents

Abstract

The invention relates to the optical industry and can be used in the formation of high-precision large-size optical surfaces. The purpose of the invention is to improve the accuracy of processing large-sized optical surfaces by smoothing the "waviness" by equidistant removal of glass with a tool that moves along the treated surface and performs uniform removal of glass on each elementary surface area. 3 il.

Description

The invention relates to the processing technology of optical parts, in particular, to the technology of automated processing of optical surfaces with a small tool and automated control of the shaping process.

The purpose of the invention is to improve the shaping accuracy of optical surfaces by eliminating waviness and, consequently, improving the characteristics of the optical system.

FIG. 1 shows an interferogram of an optical surface prior to treatment by this method; in fig. 2 is a topographic map of this surface; Fig 3 - interferogram of the optical surface after treatment in this way.

The method is implemented as follows.

At present, the quality of the surfaces of large-sized optical components is characterized by a number of parameters, the main ones of which are the average quadratic deviation of the surface from the theoretical (cc) and "surface waviness, which is now commonly referred to as small-structure error (ms.so). The optical surface, which is better than the processing cycle and meets the requirements of the kok, often has a waviness and does not satisfy the requirements for the size of msg, therefore it must be eliminated. With this chain, it is necessary to process the entire optical surface with a tool whose diameter is 3-5 times as large as the geometrical size of the elements of the waviness so that the value of the removed glass layer on each surface area is the same. The overall shape of the optical surface remains unchanged. but a smoothing of small irregularities occurs and the "undulation is eliminated. To this end, allowance for processing ft is determined by finding the maximum difference in deviations of the surface shape in two adjacent parts of the topographic map determine the minimum geometric size / of the optical surface sections with positive deviations, choose the tool diameter from condition D (3-5) /, place the tool on the optical surface, having previously pressed it, apply the required pressure to it (ten-

01

CD Ј

Yu

20 g / cm), give it a plane-parallel circular motion with eccentricity e (0.2-0.3) D and move the tool sequentially to all nodes of a square grid with speed

k-k-p-4-n

V

where h - K -

R

and

square grid spacing; a technological coefficient equal to the thickness of the removed glass layer at unit values of time, specific pressure and processing speed and is a constant value for each glass grade;

unit pressure of the tool on the part;

processing speed determined by plane-parallel circular motion;

n is the number of square grid nodes overlapped by the polishing tool.

 1 (.roz the obtained value of Y is realized by the presence of the instrument in the vicinity of each point. This speed is small compared to V i - the processing speed and therefore is not taken into account when calculating the residence time of the instrument. In those cases. moving the tool so that there is a repetition of work in any area, the pressure on the tool is reduced and the rotation of the spindle and the tool is turned off, providing a plane-parallel circular movement.

In order to eliminate possible fluctuations when glass is polished, resulting in uneven removal of glass over the surface of the part, it is necessary to eliminate the required allowance for several (3-4) tool transitions. With aspherical surfaces, machining can be performed on annular zones by placing the tool only on those nodes of the square grid that fall into the treated zone. As a result of sequential movement of the instrument from zone z, the whole optical surface is processed. To implement a good grinding of the tool to the surface to be machined, the tool in each zone is compressed. The proposed method allows to increase (shaping quality by reducing the i.s.w. and, consequently, improve the accuracy characteristics of the optical system, (modulation transfer function, frequency contrast characteristics, final - -ratation of energy in the scattering circle.) The method would be.- put into practice when forming planar, spherical and

0

aspherical surfaces on machines AD-1000 and AD-2000. FIG. 1 shows the interferogram of a spherical surface.

0 500 mm before treatment in this way. The surface has a pronounced "waviness. FIG. Figure 2 shows a topographic map of the optical surface on which the deviations from the theoretical surface are indicated in arbitrary units (each unit is equal to I. 10, where K is the wavelength of light is equal to 0.6328 microns). The diameter of the tool D in this case is 5 /,, and the value of the allowance b is equal to 10 units of the topographic map. After processing in this way the surface has become much smoother. The interferogram of this surface is shown in FIG. 3

A positive effect when using the proposed method is to improve the accuracy of shaping the surfaces of large-sized optical chips.

Claims (1)

Invention Formula 0 A method of treating surfaces of optical parts, in which a topographic map of the deviations of the processed surface is constructed in the form of a square grid, brings the polishing tool into contact with the surface being processed, applies pressure to it, imparts a plane-parallel circular movement to the tool and moves it over the surface characterized by that, in order to increase the machining accuracy, the machining allowance is determined by finding the maximum difference in the deviations of the surface shape in two tanks these nodes topographic maps, geometric determined minimum size / portions of the optical surface having a positive deflection, the diameter of the tool is selected conditions D (3 ... 5) / tool is moved sequentially in all nodes of a square grid with a velocity V h-k-p-u, -n five where h K P 0 v - P - square grid spacing; technological coefficient; unit pressure of the tool on the part; processing speed, determined by a flat parallel circular motion; the number of square grid nodes overlapped by the polishing tool. S3 MS GO - go -j- o -: oi o- -Ј h fM - o ЈЈi cm -o from -n .Ј-m / and 4 CL  h / V- / U; - ° s.  if T 7S4 ll Oh - oh; CLi (p- i / - O O) O gchz O : -1 --./o i o .- i p / i -. -. . - ---- {:; .Л, - о - .J О о Г-5 14 About E. .... , -, with:;- -- -  g  - j - - (V.а .7 t. j rj -: j.-J ir5- O ta / and 4 -f 14) about Phage.Z