Analog circuit for an autofocus microscope system

Patent RE40674 Issued on March 24, 2009.

Patent References

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Inventors

Assignee

Q3DM, LLC

Application

No. 10000943 filed on 11/30/2001

US Classes:

348/345Focus control

Examiners

Primary: Ho, Tuan V

Attorney, Agent or Firm

Caesar, Rivise, Bernstein, Cohen & Pokotilow, Ltd.

Foreign Patent References

WO 96/10196 WO 04/01/1996

International Class

H04N 5/202

Abstract

An analog circuit for an autofocus microscope system measures a degree of focus of an object directly from the video signal of a microscope CCD camera. The circuit then returns an index to a host computer for the purpose of adjusting the position of the microscope's 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. Low cost, real time autofocus is achieved with the analog circuitry of this invention, replacing more expensive dedicated, real time image processing hardware.

Other References

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