CN107144936B

CN107144936B - Processing method of optical window in differential pressure environment

Info

Publication number: CN107144936B
Application number: CN201710493477.1A
Authority: CN
Inventors: 任晓坜; 翟嘉; 任戈; 史建亮
Original assignee: Institute of Optics and Electronics of CAS
Current assignee: Institute of Optics and Electronics of CAS
Priority date: 2017-06-26
Filing date: 2017-06-26
Publication date: 2020-01-10
Anticipated expiration: 2037-06-26
Also published as: CN107144936A

Abstract

The invention discloses a method for processing an optical window in a differential pressure environment, which is characterized in that A, B two sides of the optical window are respectively placed in different pressure environments for processing. Wherein, the surface A is processed under normal pressure; then designing a sealed cavity, and installing the optical window on the sealed cavity, wherein the A surface faces inwards; adjusting the pressure difference between the inside and the outside of the sealed cavity to be the pressure difference delta P of the optical window in actual use, and then processing the surface B; and meanwhile, an instrument is adopted to detect the transmission surface shape of the optical window, and if the precision of the transmission surface shape is insufficient, the surface B is continuously processed until the transmission surface shape meets the index requirement. The method for processing the optical window under the actual differential pressure working condition can make up the optical aberration caused by the pressure deformation of the optical window when the optical window processed by the conventional method is used in the differential pressure environment.

Description

Processing method of optical window in differential pressure environment

Technical Field

The invention relates to the field of optical element processing, in particular to a processing method of an optical window used under a pressure difference working condition; the method simulates the working condition of pressure difference to deform the optical window, and the optical window is processed on the basis. The method can avoid the image quality deterioration caused by the deformation of the optical window when the traditional optical window works under the working condition of pressure difference; the method can be used in various pressure difference environments, such as hydraulic pressure, air pressure, vacuum and the like.

Background

Optical windows have wide application in optical systems, particularly in underwater detectors, high-altitude and high-speed aerial cameras, space cameras, vacuum lasers and other systems. The system is often in a complex pressure environment, the optical window not only plays a role in ensuring light transmission, but also plays a role in reducing the influence of pressure on the optical system, and because the optical window is in a pressure difference working condition, the pressure difference enables the optical window to deform, and finally the image quality is poor.

Aiming at the pressure difference working condition, the technical route of increasing the thickness of an optical window to improve the rigidity and reduce the pressure difference deformation is adopted at present. However, this method increases the weight and size of the system, and the optical window is thickened to reduce the transmittance of light; in addition, the process also increases the economic cost.

Through the literature search of the prior art, Chinese patent numbers: 201310180114, title of the invention: a method and a device for realizing a vacuum high-precision window. This patent discloses a method for implementing a stepped differential pressure vacuum window. The method ensures the surface shape precision of the window by adopting n pieces of window glass to be continuously installed and carrying out vacuumizing and inert gas recharging. However, the high-precision window has more components, large size and heavy weight, and the accumulated error is large; and the method has high economic cost.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: when the optical window processed by the traditional method is used in a pressure difference working condition, the optical window is deformed by the pressure difference to generate aberration. The invention aims to provide a method for processing an optical window used under a pressure difference working condition; the method simulates the working condition of pressure difference to deform the optical window, and the optical window is processed on the basis. The method can avoid the image quality deterioration caused by the deformation of the optical window when the traditional optical window works under the working condition of pressure difference; the method can be used in various pressure difference environments, such as hydraulic pressure, air pressure, vacuum and the like.

The technical scheme adopted by the invention is as follows: the invention discloses a processing method of an optical window in a differential pressure environment, which comprises the following steps:

step S1: the optical window is divided into A, B two surfaces, wherein the surface A is processed to the required surface shape by a conventional method, and the surface B is subjected to semi-finishing;

step S2: designing a sealing cavity with a flange, wherein the air exhaust flange is connected with an air exhaust pump; the interface flange is connected with a pressure sensor;

step S3: mounting the optical window on the sealed chamber in step S2 with the a face processed in step S1 facing inward;

step S4: a high-precision standard reflector is arranged in the sealed cavity, the position of the reflector is adjusted, so that the interferometer can detect the transmission surface shape of the optical window, and the position of the reflector is locked;

step S5: the sealed cavity is pumped by an air pump arranged on an air pumping flange;

step S6: the pressure inside and outside the sealed cavity is ensured to be consistent with the actual pressure difference working condition of the optical window by monitoring the pressure of the pressure sensor;

step S7: detecting the optical window by using an interferometer to obtain a transmission surface shape of the optical window;

step S8: processing the surface B according to the detection result of the step S7;

step S9: and repeating the step S7 and the step S8 until the transmission surface shape of the optical window meets the index requirement.

Wherein, the difference between the internal pressure and the external pressure of the sealing cavity in the step S6 specifically meets the following requirements: the external air pressure P1, the internal air pressure P2 and the pressure difference delta P between the inside and the outside of the sealed cavity are | P1-P2 |.

Compared with the prior art, the invention has the advantages that: when the optical window is processed, the processing environment is consistent with the actual use environment, so that when the optical window is used in a pressure difference working condition, the deformation of the optical window caused by the pressure difference is small, and further, the caused aberration is small; the optical window processed by the invention has the advantages of thin thickness, light weight, small volume, simple structure, high surface shape precision and strong reliability; the processing method reduces the influence of the optical window on the beam quality, and has practical significance on the optimization design of an optical system; the processing method is simple, convenient and quick, has low cost, small processing error and strong operability, and can realize the processing of optical windows with different pressure differences.

Drawings

FIG. 1 is a schematic diagram of a method for processing an optical window in a pressure differential environment.

The reference numbers in the figures mean: 1 is a sealed cavity, 2 is an optical window, 3 is an interferometer, 4 is an interface flange, 5 is an air exhaust flange, and 6 is a standard reflector.

Detailed Description

The invention is further described with reference to the following figures and detailed description.

As shown in fig. 1, a method for processing an optical window in a differential pressure environment utilizes a device mainly comprising: the optical interferometer comprises a sealed cavity 1, an optical window 2, an interferometer 3, an interface flange 4, an air exhaust flange 5 and a standard reflector 6.

The method comprises the following steps:

step S1: the optical window material is fused quartz, the caliber is 200mm, the thickness is 15mm, the optical window material is divided into A, B two surfaces, firstly, the A surface is processed by a conventional method until the required surface shape RMS is less than lambda/10, then the B surface is semi-finished, and the surface shape RMS is 2.1 lambda;

step S2: a sealed cavity with a flange is designed, wherein the air exhaust flange is connected with an air exhaust pump (the working pressure range is 101325 Pa-1 x 10)^-2Pa); the interface flange is connected with a pressure sensor (the pressure measuring range is 0-1000 Pa);

step S6: by monitoring the pressure of the pressure sensor, the pressure difference delta P between the inside and the outside of the sealed cavity is ensured to be consistent with the actual pressure difference working condition of the optical window (wherein the external air pressure P1 is 101325Pa, the air pressure P2 in the cavity is 300Pa, and the pressure difference delta P between the inside and the outside of the sealed cavity is | P1-P2 |);

step S7: detecting the optical window by using an interferometer to obtain a transmission surface shape RMS of 4.8 lambda;

step S9: and repeating the steps S7 and S8 until the optical window transmission profile meets the index requirement of RMS < lambda/10.

Claims

1. A method for processing an optical window in a pressure difference environment utilizes a device mainly comprising the following steps: sealed chamber (1), optical window (2), interferometer (3), interface flange (4), flange (5) of bleeding, standard speculum (6) are constituteed, its characterized in that: the method comprises the following steps:

step S1: the optical window material is fused quartz, the caliber is 200mm, the thickness is 15mm, the optical window material is divided into A, B two surfaces, the A surface is firstly processed until the required surface shape RMS is less than lambda/10, then the B surface is semi-finished, and the surface shape RMS is 2.1 lambda;

step S2: the design has the sealed chamber of flange, and wherein the flange of bleeding connects the aspiration pump, the operating pressure scope: 101325 Pa-1X 10^-2Pa; interface flangeAnd (3) connecting a pressure sensor, measuring a pressure range: 0 to 1000 Pa;

step S6: the pressure of the pressure sensor is monitored, so that the pressure difference delta P between the inside and the outside of the sealed cavity is consistent with the actual pressure difference working condition of the optical window, wherein the external air pressure P1 is 101325Pa, the air pressure P2 in the cavity is 300Pa, and the pressure difference delta P between the inside and the outside of the sealed cavity is | P1-P2 |;