Wavelength scanning three dimensional morphology measurement system of optical frequency comb reference

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...

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Problems solved by technology

This phase shift method often requires multiple acquisitions, which increases the time consumption of the...

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