Reduce impact of the Talbot effect in laser parallel confocal measurement within LED

Qing Yu; Ruifang Ye; Wei Fan

doi:10.1117/12.2014723

31 January 2013 Reduce impact of the Talbot effect in laser parallel confocal measurement within LED

Qing Yu, Ruifang Ye, Wei Fan

Proceedings Volume 8759, Eighth International Symposium on Precision Engineering Measurement and Instrumentation; 87593T (2013) https://doi.org/10.1117/12.2014723
Event: International Symposium on Precision Engineering Measurement and Instrumentation 2012, 2012, Chengdu, China

Abstract

The axial resolution of parallel confocal measurement can be improved as the laser source added into the system, but extreme monochromaticity of laser beam will produce the Talbot effect, which is an effect of many images of point light array appear along the optical path direction, and it causes to distinguish the true in-focus image from lots of Talbot images difficultly, which means the confocal measurement can’t be carried on. The author researched factors of the influences for Talbot distance, and developed some methods to weaken the impact of the Talbot effect. A LED was added into the laser parallel confocal measurement system to find the in-focus image, and there were no Talbot images nearby to impede positioning, and then the laser beam was lead into the system to measure with high precision. The difference of location of the two in-focus images with laser and LED was about 11μm in the experiment, which was shorter than one Talbot distance in the system, and the result indicated that the in-focal could be distinguished with this method.

Citation Download Citation

Qing Yu, Ruifang Ye, and Wei Fan "Reduce impact of the Talbot effect in laser parallel confocal measurement within LED", Proc. SPIE 8759, Eighth International Symposium on Precision Engineering Measurement and Instrumentation, 87593T (31 January 2013); https://doi.org/10.1117/12.2014723

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KEYWORDS

Light emitting diodes

Confocal microscopy

Precision measurement

Image processing

Laser sources

Charge-coupled devices

Light sources

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