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Autocollimating type confocal method for measuring focal length of lens

A technology of confocal lens and measurement method, which is applied in the direction of testing optical performance, etc., can solve problems such as unrealizable and large errors, and achieve the effect of improving the precision of focusing and improving the sensitivity of focusing

Inactive Publication Date: 2014-01-08
BEIJING INSTITUTE OF TECHNOLOGYGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the lens vertex focal length and focal length measurement methods proposed in the above documents are only suitable for measuring ultra-long focal lengths. If they are used for the measurement of general focal lengths and shorter focal lengths, the error will be large or it will not be possible.

Method used

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  • Autocollimating type confocal method for measuring focal length of lens
  • Autocollimating type confocal method for measuring focal length of lens
  • Autocollimating type confocal method for measuring focal length of lens

Examples

Experimental program
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Effect test

Embodiment 1

[0037] When the measured lens 7 has a diameter of D=25.4mm and a radius of curvature of the front surface r 1 =90.1mm, the radius of curvature of the back surface r 2 =-115.4mm, material is K9 glass, thickness b=4mm, nominal focal length and top focal length are f′=99mm, l F ′=97.5mm convex lens, the focal length measurement device of self-collimating confocal lens such as figure 2 As shown, the measurement steps are:

[0038] (a) Start the measurement software in the main control computer 18, turn on the laser 17, and the light emitted by the laser 17 is transmitted through the optical fiber 16 to form a point light source 1. The light emitted by the point light source 1 forms a parallel beam after passing through the beam splitter 2 and the collimating lens 3, and the parallel beam is converged by the converging lens 5 to form a measuring beam 6;

[0039] (b) The measured lens 7 is placed on the four-dimensional adjustment frame 23, the auxiliary plane mirror 8 is placed...

Embodiment 2

[0046] According to the radius of curvature r of the front surface of the measured lens 7 1 =90.1mm, the radius of curvature of the back surface r 2 =-115.4mm, refractive index n=1.5163, thickness b=4mm, and the top focal length l of the lens measured in Example 1 F '=97.5316mm, the focal length of the measured lens 7 can be measured indirectly:

[0047] f ′ = l F ′ + r 2 b n ( r 2 - r 1 ) + ( n - 1 ) b = 99.0216 ...

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Abstract

The invention belongs to the technical field of optical precision measurement and relates to an autocollimating type confocal method for measuring the focal length of a lens. The method comprises the following steps of: infusing the autocollimating idea into a confocal measuring method, and further realizing measurement on the vertex focal length and the focal length of the lens. The core idea comprises the following contents of: introducing an auxiliary planar reflecting mirror to reflect parallel light beams collimated by the tested lens along a light path, precisely positioning the focal point and the surface vertex of the tested lens by being matched with a confocal technology and further obtaining the vertex focal length and the focal length of the tested lens. According to the invention, the autocollimating measuring idea is infused into the confocal measuring method firstly, the positions of the focal point and the surface vertex of the tested lens are determined by utilizing the maximum value point of a confocal response curve, and the method has the advantages of high measuring precision and strong ambient interference resistance and the like, and can be used for high-precision detection on the local length of the lens.

Description

technical field [0001] The invention belongs to the technical field of optical precision measurement and can be used for the detection of the focal length of a lens and the high-precision focal length measurement in the assembly process of an optical system. technical background [0002] Focal length measurement is an ancient and classic topic of lens parameter measurement, and its importance is self-evident. The focal length is one of the most important parameters among the many parameters of the lens. For lens design, it is nothing more than adjusting various parameters to ensure that the focal length of the lens meets the design requirements and the imaging performance meets the system requirements. Lens focal length measurement usually includes vertex focal length measurement and focal length measurement. In the process of system design and adjustment, these two parameters are usually inseparable, so it is required to measure the vertex focal length and focal length of t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01M11/02
Inventor 邱丽荣张鑫杨佳苗赵维谦李志刚
Owner BEIJING INSTITUTE OF TECHNOLOGYGY
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