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Method for measuring spherical aberration of confocal system

A measurement method and spherical aberration technology, applied in the direction of testing optical performance, etc., can solve problems such as difficulty in improving measurement accuracy, and achieve the effects of improving anti-environmental interference ability, improving fixed focus sensitivity, and improving the degree of automation

Inactive Publication Date: 2012-09-12
BEIJING INSTITUTE OF TECHNOLOGYGY
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  • Claims
  • Application Information

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Problems solved by technology

[0005] In addition, scholars have also proposed methods to measure spherical aberration of optical systems using other principles. For example, the article "Application of Secondary Gratings in Wavefront Measurement" published in "Acta The secondary grating can be used to measure the wavefront of the laser beam, and then realize the measurement of the spherical aberration of the system; another example is the "Automatic Measurement System for Axial Spherical Aberration" published in "Applied Optics" which introduces a method that uses CCD to subdivide the knife-edge shadow map method to measure the spherical aberration of the system. This paper uses CCD to subdivide the knife-edge shadow image and then denoises and sharpens the image to realize the positioning of the boundary position of the bright and dark rings in the shadow image. The stepping motor and the precision screw can be controlled by the computer. The position of the knife edge is precisely controlled, and then the measurement of the spherical aberration of the system is realized. However, due to the limitation of the recognition accuracy of the boundary position of the bright and dark rings, the measurement accuracy of this method is difficult to improve.

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  • Method for measuring spherical aberration of confocal system
  • Method for measuring spherical aberration of confocal system
  • Method for measuring spherical aberration of confocal system

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Experimental program
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Effect test

Embodiment 1

[0040] When the measured system 5 is a plano-convex lens with a diameter of D=76mm, a material of K9 glass, a thickness of b=8mm, and a focal length of f′=500mm, the spherical aberration measurement device of the confocal system is as follows: Figure 4 As shown, the measurement steps are:

[0041] (a) Start the measurement software in the main control computer 13, turn on the laser 20, and the light emitted by the laser 20 is transmitted through the optical fiber 19 to form the point light source 1. The light emitted by the point light source 1 passes through the beam splitter 2, the collimating lens 3 and the annular pupil 4 to form an annular beam with a flat wavefront;

[0042] (b) the plane mirror 7 is placed on the two-dimensional adjustment frame 17, and the plane mirror 7 is adjusted by the two-dimensional adjustment frame 17 so that its surface is perpendicular to the optical axis of the collimating lens 3;

[0043] (c) The system under test 5 is placed between the a...

Embodiment 2

[0053] According to the measured system 5 measured in embodiment 1, the light passing height is h 1 ~ h n The corresponding spherical aberration δL 1 '~δL n ′, it can be obtained by interpolation method that when the normalized light transmission height is 1.0, 0.85, 0.7071, 0.5, 0.3, the spherical aberration corresponding to the measured system 5 is respectively δL a '=-3.1827mm, δL b '=-2.2959mm, δL c '=-1.5989mm, δL d '=-0.7923mm, δL e '=-0.2845 mm. In order to comprehensively and generally express the spherical aberration of the measured system 5 under different light-passing heights, δL is usually taken a ', δL b ', δL c ', δL d ', δL e 'These five representative spherical aberrations describe the structure of the entire beam.

Embodiment 3

[0055] The difference from Embodiments 1 and 2 is that in this embodiment, the annular pupil is replaced by an amplitude-type spatial light modulator, and the parallel beam is converted into an annular beam with a certain light-passing height through the amplitude-type spatial light modulator, and then the The measurement process of the spherical aberration of the system. The switching speed of the ring beam and the degree of automation of the measurement system can be improved by the amplitude-type spatial light modulator.

[0056] This embodiment realizes the measurement of the spherical aberration of the system under test 5 through a series of measures. During the measurement process, the confocal measurement method is used to precisely focus the beam focus of the system under test 5 under different annular pupils, and then measure the spherical aberration of the system under test 5, with high measurement accuracy and strong anti-environmental interference ability .

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Abstract

The invention belongs to the technical field of optical precision measurement and relates to a method for measuring a spherical aberration of a confocal system. According to the method, an annular pupil filtering technology is fused with a confocal focus-fixing technology, for measuring distances moved by focus points of annular light beams with different light-passing heights after passing by a measured system, thereby obtaining the spherical aberration of the measured system. A confocal measuring technology is firstly expanded to the field of the measurement of the spherical aberration of the system according to the method provided by the invention; the method has the advantages of high measuring precision, simple light path, high environmental disturbance resistance, and the like; and the method is suitable for the high-precision detection of the spherical aberration of the system.

Description

technical field [0001] The invention belongs to the technical field of optical precision measurement and can be used for high-precision detection of spherical aberration of optical mirror groups and lenses. technical background [0002] For an imaging system, aberration is an important indicator that affects its imaging quality. If the imaging system is an ideal optical system, the light emitted by the same object point will be focused to the same ideal image point after passing through the optical system. However, due to the existence of aberration, the light of the same object point will form an astigmatic beam with complex geometric structure in the image space after passing through the actual optical system, which will seriously affect the imaging quality of the imaging optical system. On-axis spherical aberration is an important form of many aberrations, and its size will seriously affect the performance of optical systems such as collimator lenses and beam expanders. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01M11/02
Inventor 邱丽荣赵维谦杨佳苗吴华玲邵荣君李志刚
Owner BEIJING INSTITUTE OF TECHNOLOGYGY