Development of an auto-focus system based on the moire method

NCUIR > Engineering College > Graduate Institute of opto-Mechatronics > journal & Dissertation > Item 987654321/49945

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/49945

Title:	Development of an auto-focus system based on the moire method
Authors:	Lee,JY;Wang,YH;Lai,LJ;Lin,YJ;Chang,YH
Contributors:	光機電研究所
Keywords:	GRATINGS
Date:	2011
Issue Date:	2012-03-27 16:27:07 (UTC+8)
Publisher:	國立中央大學
Abstract:	An auto-focus system based on the moire effect and a feedback control method is presented. First, a collimated laser beam passes through a focusing lens then falls incident on the surface of the sample. The deviation of the angle of the light reflected back is proportional to the defocus distance from the sample. The reflected light then passes through two spiral gratings, producing three types of moire pattern which can be observed and recorded by a linear CCD. The defocus distance can be derived from the spiral angle in the moire pattern. The results show that auto-focusing can be achieved by the moire method for glass and mirror samples in a cycle time of less than 0.1 s. (C) 2011 Elsevier Ltd. All rights reserved.
Relation:	MEASUREMENT
Appears in Collections:	[Graduate Institute of opto-Mechatronics] journal & Dissertation

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