Difference Frequency Active Scanning Grating Displacement Sensor and Measurement Method

Abstract

The invention discloses a difference frequency active scanning type grating displacement sensor and a measuring method, which achieving the grating measurement based on grating pitch and solving the problem of high-precision measurement in a macro-micro cross-scale measurement. The specific implementation method comprises the following steps of: dividing the measured displacement L into two partsof L<n> and delta 1, wherein the size of L<n> is n / 4 (n=0, 1, 2, 3 and the like) times the main grating pitch P<1>, and is acquired by a grating measuring method; delta 1 is the part that less than aquarter of P<1> in the measured displacement, firstly recording a phase difference as shown in the specification / description of the main grating reading unit at Ln and the measuring grating reading unit signal, then recording a signal phase difference as shown in the specification / description of the two reading units at the final position L, and finally subjecting the two reading units to secondary movement delta L by a micro movement element, so that the phase difference of the signal is recovered from the phase difference as shown in the specification / description to the phase difference as shown in the specification / description to obtain a equation of delta 1 = (P<1>-P<2>)*delta L / P<2>; and finally obtaining the measured displacement value L= L<n>+delta 1. According to the difference frequency active scanning type grating displacement sensor and a measuring method, the grid distance difference (P<1>-P<2>) is used as a measurement reference, and a higher measurement resolution (greater than the micro movement element resolution) is obtained through the micro movement element in the range of P<1> / 4.

Description

technical field [0001] The invention belongs to the technical field of precision measurement, in particular to a difference frequency active scanning grating displacement sensor and a measurement method. The sensor and measuring method are mainly used for the measurement of linear displacement and angular displacement. Background technique [0002] The high-precision grating measurement system is a large-scale nano-measurement device with a precision second only to the laser interferometer, and it plays a very important role in the equipment manufacturing industry. It takes the pitch of the grating as the measurement benchmark, and has the advantages of good environmental adaptability, compact system structure and low price and cost. [0003] At present, the resolution of the high-precision grating measurement system mainly depends on the marking technology capability of the grating lines and the subdivision multiple of the grating Moiré fringes. At present, the grating wi...

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Problems solved by technology

However, under such a high subdivision multiple, there are almost strict requirements on the waveform and orthogonality of the original fringe signal, which brings great difficulty to installation and debugging.

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