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A Wavelength Scanning 3D Shape Measurement System Referenced by an Optical Frequency Comb

A technology of wavelength scanning and three-dimensional topography, which is applied in the direction of measuring devices, optical devices, instruments, etc., can solve the problems of increased environmental impact of measurement results, increased measurement time consumption, etc., to achieve fast measurement, slow measurement speed, and measurement The effect of error reduction

Active Publication Date: 2019-08-02
TSINGHUA UNIV
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Problems solved by technology

This phase shift method often requires multiple acquisitions, which increases the time consumption of the measurement, and the longer measurement time makes the measurement results greatly affected by the environment

Method used

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  • A Wavelength Scanning 3D Shape Measurement System Referenced by an Optical Frequency Comb
  • A Wavelength Scanning 3D Shape Measurement System Referenced by an Optical Frequency Comb
  • A Wavelength Scanning 3D Shape Measurement System Referenced by an Optical Frequency Comb

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Embodiment Construction

[0027] The implementation of the present invention will be described in detail below in conjunction with the drawings and examples.

[0028] Such as figure 1 As shown, the measurement system of the present invention includes a tunable laser light source system based on an optical frequency comb reference and an interferometric optical path system. It specifically includes femtosecond optical frequency comb 1, high-precision wavelength meter 2, external cavity semiconductor tunable laser 3, beat frequency detection and locking feedback module 4, pinhole filter 5, reference plane 6, imaging lens group 7 and CCD 8.

[0029]Femtosecond Optical Frequency Comb 1 is a fully stable femtosecond pulsed mode-locked laser. The laser corresponds to a series of frequencies arranged at equal intervals in the frequency domain. Because its shape is similar to a comb, it is also called an optical frequency comb. The frequency corresponding to each comb tooth is determined by the repetition f...

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Abstract

A wavelength scanning three dimensional morphology measurement system of optical frequency comb reference comprises an optical frequency comb reference tunable light source module and a Fizeau interferometer module, the optical frequency comb reference tunable light source module comprises a femtosecond optical frequency comb, a wavemeter, a tunable laser and a beat frequency detection and locking feedback module, and the femtosecond optical frequency comb provides the optical frequency reference capable of tracing back to an atomic clock. According to the present invention, a set of tunable light source system which can is tunable in a large range and has the very high frequency stability, is realized, a measurement error caused by the light source frequency stability is reduced substantially, and by introducing a Fourier transform phase measurement method in the Fizeau interferometer module, the measurement time is reduced, and the phase measurement precision is improved. The wavelength scanning three dimensional morphology measurement system of the present invention can measure the three dimensional morphology of the surface of an object accurately, does not have the strict requirements and limit for the height variation of the object, realizes the comprehensive measurement precision not more than 20 nanometers, and has the stronger versatility.

Description

technical field [0001] The invention belongs to the technical field of laser interference three-dimensional shape measurement, in particular to a wavelength-scanning three-dimensional shape measurement system referenced by an optical frequency comb. Background technique [0002] In traditional interferometry, since only a single-wavelength light source is used for illumination, when the height of the target object exceeds one wavelength, the measurement results will be confused. This is because the essence of interferometry is to detect the phase difference between the light reflected by the target object and the reference light. Since the phase difference of light is 2π folded, that is, multiple target depths separated by integer multiples of the wavelength correspond to the same phase difference. , so that if the height difference of the measurement target exceeds one wavelength, it is difficult to accurately determine the true corresponding height of the object from the p...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01B11/24
CPCG01B11/2441
Inventor 张伟鹏尉昊赟杨宏雷李岩
Owner TSINGHUA UNIV
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