Full Content is available to subscribers

Subscribe/Learn More  >
Proceedings Article

Analog autofocus circuit design for scanning microscopy

[+] Author Affiliations
Miguel E. Bravo-Zanoguera, Jeffrey H. Price

Univ. of California/San Diego (USA)

Proc. SPIE 2982, Optical Diagnostics of Biological Fluids and Advanced Techniques in Analytical Cytology, 468 (May 2, 1997); doi:10.1117/12.273647
Text Size: A A A
From Conference Volume 2982

  • Optical Diagnostics of Biological Fluids and Advanced Techniques in Analytical Cytology
  • Alexander V. Priezzhev; Toshimitsu Asakura; Robert C. Leif
  • San Jose, CA, USA | February 08, 1997

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.

© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Citation

Miguel E. Bravo-Zanoguera and Jeffrey H. Price
"Analog autofocus circuit design for scanning microscopy", Proc. SPIE 2982, Optical Diagnostics of Biological Fluids and Advanced Techniques in Analytical Cytology, 468 (May 2, 1997); doi:10.1117/12.273647; http://dx.doi.org/10.1117/12.273647


Access This Proceeding
Sign in or Create a personal account to Buy this proceeding ($15 for members, $18 for non-members).

Figures

Tables

NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging & repositioning the boxes below.

Related Book Chapters

Topic Collections

Advertisement
  • Don't have an account?
  • Subscribe to the SPIE Digital Library
  • Create a FREE account to sign up for Digital Library content alerts and gain access to institutional subscriptions remotely.
Access This Proceeding
Sign in or Create a personal account to Buy this proceeding ($15 for members, $18 for non-members).
Access This Proceeding
Sign in or Create a personal account to Buy this article ($15 for members, $18 for non-members).
Access This Chapter

Access to SPIE eBooks is limited to subscribing institutions and is not available as part of a personal subscription. Print or electronic versions of individual SPIE books may be purchased via SPIE.org.