Measure transparent elements using least squares iterative phase shift method

Abstract

In order to measure the surface phase of the front and back of the transparent plate more accurately, a phase shift algorithm based on least squares iteration is proposed. After a least squares phase shift algorithm, the corresponding transparent flat surface pattern can be obtained, but the accuracy of the obtained surface map is not high because there is an error in the initial phase value. Therefore, it is necessary to derive the accurate phase value from the obtained surface map. The algorithm calculates the more accurate initial phase shift value by the method of least squares and multiple iterations. After the simulation experiment of the method, it is known that the measurement accuracy of this algorithm is high and the anti-noise ability is better. The error of the PV value and RMS value of the surface map is less than 0.006λ. In actual measurement results, the PV error of the measurement result is less than 0.09λ, and the RMS error is less than 0.02λ. The measured shape is close to the true shape of the object, and the measurement accuracy is high.

Keywords

• interference
• least squares iterative algorithm
• phase shift algorithm
• shape detection
• multi-surface interference