Device and method for measuring synchronous phase shifting interference of Fizeau quasi-common optical path structure

Abstract

The invention relates to a device and a method for measuring synchronous phase shifting interference of a Fizeau quasi-common optical path structure. The device comprises a laser, a half wave plate, a focusing lens, a spatial filter, a circularly polarized light beam splitter (an optically active crystal), a spectroscope, a collimating lens, a reference mirror, a pin-hole diaphragm, an imaging lens, a light splitting and phase shifting system, a computer control system and a CCD camera. According to the device and the method disclosed by the invention, a synchronous phase shifting technology is combined with a Fizeau interference method, so that technical difficulties of a conventional interferometer in poor stability and disability of realizing dynamic measurement are solved; the device and the method are characterized by utilizing an optical rotation effect of the crystal and adding the circularly polarized light beam splitter with a very small splitting angle in the Fizeau interfering structure, so as to realize orthogonally polarized separation of reference lights and test lights in a common optical path. The device and the method disclosed by the invention avoid utilization of a high-quality quarter wave plate in a synchronous phase-shifting interference system, and also greatly decrease a phase measurement error caused by a stress birefrigent effect which exists in an optical element of the system.

Description

technical field [0001] The invention belongs to the field of optical detection, and relates to an interferometry device and method, in particular to a Fizeau type synchronous phase-shift interferometry device and method. Background technique [0002] Interferometry technology is a recognized non-contact high-precision measurement method, which is widely used in a series of measurements involving the concept of optical path difference, such as surface shape detection of optical components, small deformation of materials, and uniformity of refractive index. Phase-Shifting Interferometry PSI (Phase-Shifting Interferometry) measurement technology was first proposed by Burning et al. Using digital wavefront phase detection technology, it realized high-precision, real-time and fast automated testing, greatly expanded the measurement function of the interferometer, and improved the test performance. Efficiency has promoted the improvement of modern optical manufacturing level. How...

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Problems solved by technology

[0005] The publication number of the Chinese patent "Synchronized Phase Shift Fizeau Interferometer for Real-time Measurement" is CN102580414A, and the publication date is August 2012. This patent uses a quarter-wave plate instead of a standard flat crystal to allow the object light and reference light to pass through Interference occurs after the common path, which can realize real-time measurement, but this method requires a high-quality quarter-wave plate, which is expensive, and it is not easy to realize the measurement of large-diameter spherical or aspheric mirrors

[0006] The U.S. patent "Interferometric system with reduced vibration sensitivity and related method" publication number is: US00265017A1, and the publication date is February 2012. This patent uses a Wollaston prism with birefringence function to achieve the object light and reference light in the Fizeau type optical path. Orthogonal polarization separation, but in order to achieve polarization phase-shifting interference, this patented method needs to add a quarter-wave plate, which increases the system cost and increases the difficulty of system operation

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