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Double frequency He-Ne laser optical feedback distance measuring apparatus

A laser feedback and laser technology, applied in the direction of lasers, laser components, distance measurement, etc., can solve the problems affecting the accuracy of laser ranging, large beam divergence angle, limited application range, etc., to achieve high cost performance, simple signal processing, and structure simple compact effect

Inactive Publication Date: 2008-09-10
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to the large divergence angle of the semiconductor laser beam, the collimation and focusing system is essential in the feedback optical system, which limits its application range
Moreover, the temperature drift of semiconductor lasers is large, which seriously affects the accuracy of laser ranging

Method used

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  • Double frequency He-Ne laser optical feedback distance measuring apparatus
  • Double frequency He-Ne laser optical feedback distance measuring apparatus
  • Double frequency He-Ne laser optical feedback distance measuring apparatus

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] The experimental device of this embodiment is as figure 1 As shown, it includes a first inner cavity mirror 1, a second inner cavity mirror 4, a gain tube 2, an antireflection window 3, a first piezoelectric ceramic 5, a quartz crystal 14, a second piezoelectric ceramic 7, a laser The external cavity mirror 6, the polarization beam splitter 8, the first photodetector 9, the second photodetector 10 and the computer 13 are fed back. figure 1 The reflectivity of the first inner cavity mirror 1 and the second inner cavity mirror 4 are 99.9% and 99.4%, respectively, and the distance between them, that is, the laser cavity length L is 135 mm. There is He and Ne mixed gas in the gain tube 2, and the gas pressure ratio of He and Ne is 7:1. The anti-reflection window 3 is fixed at one end of the above-mentioned gain tube 2. The first inner cavity mirror 1, the gain tube 2, the antireflection window 3, and the second inner cavity mirror 4 together constitute a He-Ne laser with a se...

Embodiment 2

[0058] Such as figure 2 As shown, the structure of this embodiment is basically the same as that of the first embodiment, except for the anti-reflection window 3 and the quartz crystal 14. This embodiment replaces the quartz crystal 14 and the anti-reflection window 3 in the first embodiment with an anti-reflection window 3 coated with anti-reflection coatings on both sides and a stress applying device 15 clamped on the window. The anti-reflection window 3 is a window with anti-reflection coatings plated on both sides and fixed on one end of the gain tube 2. figure 2 The stress applying device 15 in is a force ring with screws, which applies a stress to the anti-reflection window 3 along the axis of the laser. Due to the stress-birefringence effect of the anti-reflection window 3, a frequency is split For two frequencies. The first inner cavity mirror 1, the gain tube 2, the antireflection window 3, the second inner cavity mirror 4 and the stress applying device 15 together cons...

Embodiment 3

[0060] Such as image 3 As shown, the structure of this embodiment is basically the same as that of the first embodiment, except for the anti-reflection window 3 and the quartz crystal 14. In this embodiment, a quartz crystal wedge 16 with anti-reflection coatings on both sides replaces the quartz crystal 14 and the anti-reflection window 3 in the first embodiment. The quartz crystal wedge 16 is fixed to the above-mentioned gain tube close to the second inner cavity mirror. 4 at one end. Both sides of the quartz crystal wedge 16 are coated with anti-reflection coatings, which are fixed on one end of the gain tube 2 for frequency splitting. The first inner cavity mirror 1, the gain tube 2, the quartz crystal wedge 16 and the second inner cavity mirror 4 together constitute a dual-frequency He-Ne laser.

[0061] The dual-frequency He-Ne laser optical feedback rangefinder designed by the present invention is composed of a dual-frequency He-Ne laser, a laser feedback external cavity, ...

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Abstract

The invention relates to a light feedback telemeter for a double frequency He-Ne laser, belonging to the technical field of laser measurement. The telemeter comprises the double frequency He-Ne laser, an external cavity of laser feedback, a measurement circuit and a data processing system, wherein, the He-Ne laser comprises a gain tube, an antireflective window plate fixed on one end of the gain tube and a resonator; the resonator comprises a reflecting mirror of a first internal cavity fixed on the other end of the gain tube, a reflecting mirror of a second internal cavity fixed on the other end of the antireflective window plate, quartz crystal and a first piezoceramics. In the course of measuring, a second piezoceramics pushes the reflecting mirror of the external cavity of laser feedback to move from left to right along the laser axes so as to produce two lines of cross-polarized laser feedback signals and a phase difference exists between the two lines of cross-polarized laser feedback signals in direct proportion to the length of feedback external cavity. The telemeter is characterized by simple and compact structure as well as high performance.

Description

Technical field [0001] The invention relates to a dual-frequency He-Ne laser optical feedback rangefinder, which belongs to the technical field of laser measurement. Background technique [0002] Self-mixing interference or optical feedback refers to the phenomenon that in laser application systems, after the laser output light is reflected or scattered by external objects, part of the light is fed back into the laser and mixed with the light in the cavity, which causes the laser output power to change. The traditional two-beam interference signal is similar. [0003] Since self-mixing interference seriously affects the performance of the laser, researchers initially focused on how to eliminate or avoid the impact of light feedback on the laser system. In 1963, King first reported the phenomenon of self-mixing interference. When a movable external mirror reflects the laser output light back to the laser cavity, the laser power fluctuates, and the laser power fluctuates every time...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01S17/08G01C3/00H01S3/223H01S3/08
Inventor 张书练谈宜东
Owner TSINGHUA UNIV
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