Continuous variable-angle digital holographic metrology method and device

Abstract

The invention discloses a continuous variable-angle digital holographic metrology method and a continuous variable-angle digital holographic metrology device for complicated face type and belongs to the technical field of photoelectric measurement. The device comprises a laser, an optical fiber beam splitter, an optical fiber phase shifter, a precision angle deflection device, an off-axis paraboloid calibrator, a collimating lens group, a light combining prism, an optical fiber, a charge coupled device (CCD) camera, a computer and the like. The invention is characterized in that a precision angle deflection structure in a system can precisely change the direction of reference light in a multi-angle mode; when an angle is changed, a hologram which is generated by interference of the reference light and object light can be changed; and a wrapped phase value of an object at each angle is obtained by controlling the optical fiber phase shifter and using a phase shifting method; cosines of the wrapped phase values are added to obtain a function, and peak search is performed, so the height information of each point of the object can be obtained. The invention has the advantages that all points of the object to be measured are separately measured in the measurement process, a phase unwrapping step is eliminated, and face type parameters of the object which has complicated shape and is interrupted can be measured.

Description

technical field [0001] The invention relates to a method and device for continuously variable angle digital holographic interferometry of complex surface objects, belonging to the field of photoelectric measurement technology. Background technique [0002] Digital Holographic Metrology (Digital Holographic Metrology) is a technology that uses holographic methods for interferometry. It has the advantages of non-contact, full-field measurement, high precision, high sensitivity, and quick and easy measurement. It can be used for flatness, common The measurement of surface parameters such as surface degree and thickness has broad application prospects in precision machinery, aerospace and other fields. [0003] After literature search, it is found that the existing digital holographic information demodulation methods are divided into two types. The first is the phase shift demodulation method, which uses a phase shifter to introduce a known phase shift to obtain the package phas...

AI Technical Summary

Problems solved by technology

Although this method can measure complex profiles, due to the use of tunable lasers, there are disadvantages such as complex equipment structure, high cost, narrow laser tunable range, and limited tuning accuracy, which limits its practical application effect.

Images