Abstract
To accomplish the simultaneous measurement of motion errors for a topography measurement system, a 3-DoF (Degree of Freedom) motion error measurement system based on film interferometry is proposed. An optical flat was the moving unit, whereas a prism group consisting of two equilateral prisms and a right-angle prism formed the stationary sensing head. There was an air wedge between the prism group and the optical flat. A horizontally incident laser beam was used to generate an interferogram, the phase shift of which was directly related to the standoff variation, yaw, and roll. The interferogram was captured by a camera and combined with an in-house-developed image processing algorithm, and the above three motion errors could be simultaneously obtained. The experimental results demonstrated that the linear and angular measurement accuracies of the system were ±0.08 µm and ±0.55″, and the repeatability represented by the standard deviation was within 40 nm and 0.4″.
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