Analog autofocus circuit design for scanning microscopy

Miguel E. Bravo-Zanoguera; Jeffrey H. Price

doi:10.1117/12.273647

2 May 1997 Analog autofocus circuit design for scanning microscopy

Miguel E. Bravo-Zanoguera; Jeffrey H. Price

Author Affiliations +

Proceedings Volume 2982, Optical Diagnostics of Biological Fluids and Advanced Techniques in Analytical Cytology; (1997) https://doi.org/10.1117/12.273647
Event: BiOS '97, Part of Photonics West, 1997, San Jose, CA, United States

Abstract

The description of an analog autofocus circuit design, developed for a scanning microscope, is presented. The analog circuit measures the degree of focus directly from the video signal of the microscope CCD camera. The circuit then returns an index to the host computer for the purpose of adjusting the position of the objective lens to bring the object in focus. Best focus is found by comparing indices at several different vertical positions. The criterion adopted for determining the degree of focus is derived from the energy distribution of the video signal spectrum. The high frequency energy of the video spectrum is a maximum at best focus and as the optics defocus, the distribution shifts to lower frequencies. A previous digital autofocus implementation required dedicated real time image processing hardware. Real time autofocus is an order of magnitude less expensive with the analog circuitry described here than it was with the dedicated digital pipeline image processing. The characteristics of the analog design and its performance are compared to that of the previous digital implementation.

Citation Download Citation

Miguel E. Bravo-Zanoguera, Miguel E. Bravo-Zanoguera, Jeffrey H. Price, Jeffrey H. Price, } "Analog autofocus circuit design for scanning microscopy", Proc. SPIE 2982, Optical Diagnostics of Biological Fluids and Advanced Techniques in Analytical Cytology, (2 May 1997); doi: 10.1117/12.273647; https://doi.org/10.1117/12.273647

ACCESS THE FULL ARTICLE

PERSONAL SIGN IN
Full access may be available with your subscription

Email or Username Forgot your username?

Password Forgot your password?

Show

Remember Email/Username on this computer

Remember Password

No SPIE account? Create an account
or Institutional Sign In via Shibboleth

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members: $14.40

Non-members: $18.00 ADD TO CART

Show All Keywords

Keywords/Phrases

Search In:

Publication Years