Diffraction analysis and evaluation of a focus-error detection scheme for an optical profilometer

Chunlan Yang; Zhaobang Pu; Huijie Zhao

doi:10.1117/12.402613

9 October 2000 Diffraction analysis and evaluation of a focus-error detection scheme for an optical profilometer

Chunlan Yang, Zhaobang Pu, Huijie Zhao

Proceedings Volume 4221, Optical Measurement and Nondestructive Testing: Techniques and Applications; (2000) https://doi.org/10.1117/12.402613
Event: Optics and Optoelectronic Inspection and Control: Techniques, Applications, and Instruments, 2000, Beijing, China

Abstract

A high resolution non-contact optical sensor for surface roughness has been developed. The principle of the sensor is based on the dynamic focusing in combination with astigmatic method, a popular focus-error detection approach. The measuring principle of the method and the optical system arrangement are described in detail firstly. Then, a mathematical model of the system based on Fresnel diffraction theory is derived. According to the model, a plot of the focus error signal (FES) versus the misfocusing is easily got. The effect of various system parameters on the FES is discussed, and this is very useful for system optimization. Besides, results of numerical calculation, namely optical field distributions on the quadrant photodetector surface at different misfocusing, are presented.

Citation Download Citation

Chunlan Yang, Zhaobang Pu, and Huijie Zhao "Diffraction analysis and evaluation of a focus-error detection scheme for an optical profilometer", Proc. SPIE 4221, Optical Measurement and Nondestructive Testing: Techniques and Applications, (9 October 2000); https://doi.org/10.1117/12.402613

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