Gaussian laser beam divergence angle measurement device and method

Through the measurement method based on the bulk phase grating, the laser beam divergence angle is measured using optical elements and CCD cameras, which solves the problem of insufficient accuracy in the prior art and realizes high-precision divergence angle measurement.

CN115560849BActive Publication Date: 2025-08-12SHANGHAI INST OF OPTICS & FINE MECHANICS CHINESE ACAD OF SCI
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Patent Information

Application Number
CN202211260075.4
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2022-10-14
Publication Date
2025-08-12
Estimated Expiration
2042-10-14

AI Technical Summary

Technical Problem

The existing laser beam divergence angle measurement methods have problems such as insufficient accuracy, operation relies on artificial operations, and are not suitable for batch measurement. In particular, the measurement accuracy of the CCD measurement method is limited by lens aberration and device length.

Method used

Using a measurement method based on two-pass body phase gratings, polarization spectroscopic prism, body phase grating, 1/4 wave plate, mirror, achromatic lens and CCD camera, the optical path distance is changed by moving the mirror, and the proportion of zero-order spot intensity is measured, and the divergence angle is calculated based on the fitting formula.

Benefits of technology

It achieves high-precision measurement of divergence angles as low as 10 microradians, which is more accurate than CCD measurement method and is suitable for batch measurement.

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Abstract

The present invention relates to the field of laser detection technology and discloses a Gaussian laser beam divergence angle measurement device and method. The method comprises: passing the laser beam to be measured through a polarization beam splitter prism, being incident normally on a volume phase grating and a quarter-wave plate, and being split into three light spots with light intensities of approximately 0.25:0.5:0.25. The light is then reflected by a reflector, passed again through the quarter-wave plate and the volume phase grating, and reflected by the polarization beam splitter prism to a CCD camera. By varying the distance from a reflector with a movable mirror frame to the volume phase grating, the proportion of the zero-order light spot intensity in the total light spot intensity at different distances x0 is obtained. The divergence angle of the laser beam to be measured is then fitted using a formula based on the relationship between the intensity proportion of the zero-order light spot and the beam divergence angle.
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