Phase shifting interferometry-based sphere diameter absolutely-precise measuring system and method thereof

Abstract

The invention relates to a phase shifting interferometry-based sphere diameter absolutely-precise measuring system and a method thereof. The phase shifting interferometry-based sphere diameter absolutely-precise measuring system comprises a tunable laser, a polarization-maintaining optical fiber system, a laser frequency locking system, a laser frequency tracing system and a sphere diameter interferometer which are mutually connected. According to the invention, the method which is used for interfering phase control based on frequency scanning by the tunable laser is adopted, thus the phenomena of mechanical vibration and nonlinearity caused when piezoelectric ceramic is used for interfering phase control are avoided and the accuracy for phase shift control is enhanced; a Fabry-Perot cavity is additionally adopted, the outputted laser frequency is locked at a transmission peak of the Fabry-Perot cavity, and then an assumption of equally-spaced phase shift required by an asynchronous sampling phase shift algorithm is strictly ensured and the calculating accuracy of the phase shift algorithm is enhanced; and in addition, the femtosecond optical frequency combing system-based laser frequency tracing system is further adopted, the output laser frequency of the tunable laser can be traced to the microwave frequency standard, thus a diameter measuring result of a sphere to be measured has metrological significance.

Description

technical field [0001] The invention belongs to the technical field of precision measurement, and in particular relates to an absolute precision measurement system and method of a sphere diameter based on phase shift interference. Background technique [0002] The absolute precision measurement of the diameter of a sphere has a wide range of application requirements in the field of metrology such as the accurate measurement of Avogadro's constant. When using the X-ray crystal density method to accurately measure the Avogadro constant, it is necessary to precisely measure the diameter of a single crystal silicon sphere with a diameter of about 94 mm and a mass of about 1 kg, so as to calculate the volume of the silicon sphere. Due to the improvement of silicon sphere processing technology, its roundness has been better than 100nm, and its surface roughness has been better than 0.2nm. Through theoretical analysis, the error caused by the roundness of silicon spheres when calcu...

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Problems solved by technology

[0003] In order to overcome the deficiencies in the above-mentioned prior art, the object of the present invention is to provide an absolute precision measurement system and method for the diameter of a sphere based on phase-shift interference, which avoids the need for the existing measurement system to use piezoelectric ceramics for interferometric phase control. The mechanical vibration and non-linear phenomenon caused seriously affect the accuracy of the measurement, and the precise measurement of the diameter of the sphere is truly realized.

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