[1] [1] FENG H J,MAO B F,LI Q.An auto-focusing system used for digital imaging ［J］.Opto-Electronic Engineering,2004,31(10): 69-72.(in Chinese)

[2] [2] CHEN L G,WANG M Y,YANG ZH L,et al..Fast autofocus method for microscopic computer vision［J］.Opt. Precision Eng.,2010,18(6): 1361-1366.(in Chinese)

[3] [3] LUO J,SUN L,MIN ZH SH.Application of zoom tracking curves in focusing［J］.Opt. Precision Eng.,2011,19(10): 2326-2332.(in Chinese)

[4] [4] FAN Y Y,SHEN X H,SANG Y J.No reference image sharpness assessment based on contrast sensitivity［J］.Opt. Precision Eng., 2011, 19(10): 2485-2493.(in Chinese)

[5] [5] WANG ZH L,LIU J Y,JIA Y D.Image sensing technology based on CCD and CMOS［J］.Optical Technique,2003,29(3): 361-364.(in Chinese)

[6] [6] SUZUKI K,TSUDA S, DEGUCHI T.VCM design with round coil and axe-shaped magnet for hard disk drive actuator［J］.Microsystem Technologies,2007,13(8-10): 1093-1101.

[7] [7] ANALOG DEVICES.AD5820 datasheet［EB/OL］.［2012-02-11］ http: //www.datasheet4u.net/download.phpid=574609.

[8] [8] OMNI VISION INC.OV5642 datasheet［EB/OL］.［2012-04-16］http: // download.csdn.net/detail/lishrise/3535073.

[9] [9] ZHANG Y J,LIANG W.Design of picture memory system based on DSP and singlechip［J］. Communications Technology,2010,43(2): 66-67.(in Chinese)

[10] [10] LIANG M H,WU ZH Y,CHEN T. Auto-focusing adjustment of theodolites by the largest gradient method［J］.Opt. Precision Eng., 2009,17(12): 3016-3021.(in Chinese)

[11] [11] GAMADIA M,KEHTARNAVAZ N.Real-time implementation of single-shot passive auto focus on DM350 digital camera processor［J］. Proc.SPIE, 2009, 7244: 24408-24415.

[12] [12] HU T,CHEN SH ZH,LIU G D.Algorithm of rapid auto-focusing with a long-range［J］.Journal of Optoelectronics·Laser,2006,17(4): 464-467.(in Chinese)