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Method for measuring focal length of reflection type differential confocal lens

A technology of differential confocal and measurement method, which is applied in the direction of testing optical performance, etc., can solve the problems of large error and impossibility, and achieve the effect of improving the precision of focusing and improving the sensitivity of focusing

Active Publication Date: 2012-07-18
BEIJING INSTITUTE OF TECHNOLOGYGY
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  • 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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  • Method for measuring focal length of reflection type differential confocal lens
  • Method for measuring focal length of reflection type differential confocal lens
  • Method for measuring focal length of reflection type differential confocal lens

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] When the measured lens 5 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 vertex focal length are f′99mm, l F ′=97.5mm convex lens, reflective differential confocal lens focal length measuring device such as figure 2 As shown, the measurement steps are:

[0039] (a) Start the measurement software in the main control computer 21, 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 and the collimator lens 3 to form a parallel beam;

[0040] (b) Place the plane mirror 6 on the two-dimensional adjustment frame 26, adjust the plane mirror 6 by the two-dimensional adjustment frame 26, so that its surface is perpendicular to the optical axis of the p...

Embodiment 2

[0047] According to the radius of curvature r of the front surface of the measured lens 5 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 '=97.4716mm, the focal length of the measured lens 5 can be measured indirectly:

[0048] f ′ = l F ′ + r 2 b n ( r 2 - r 1 ) + ( n - 1 ) b = 98.9616 ...

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Abstract

The invention belongs to the technical field of optical precision measurement and relates to a method for measuring the focal length of a reflection type differential confocal lens. The method comprises the following steps of: precisely positioning the positions of the surface vertex and the focal point of the lens by being matched with a planar reflecting mirror through a differential confocal measuring method, and further measuring the vertex focal length and the focal length of the lens. The invention firstly provides a method for realizing precise positioning of the focal length by virtue of a characteristic that a differential confocal response curve corresponds to the focal point and the surface vertex of the tested lens when passing the zero point, and expands the differential confocal measuring technology into the field of measurement on the focal length of the lens; and the method has the advantages of high measuring precision and strong ambient interference resistance, and can be used for high-precision detection of 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 Applications(China)
IPC IPC(8): G01M11/02
Inventor 赵维谦杨佳苗邱丽荣李佳吴华玲
Owner BEIJING INSTITUTE OF TECHNOLOGYGY
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