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Apparatus for Evaluation of Lenses by Direct Measurement of The Normalized Value of the Peak Intensity in the Point Spread Function (Strehl Ratio)

IP.com Disclosure Number: IPCOM000099661D
Original Publication Date: 1990-Feb-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 76K

Publishing Venue

IBM

Related People

Bobroff, N: AUTHOR [+2]

Abstract

The peak intensity in the image of an infinitesimal object is an excellent measure of the image quality provided by an optical system. To be useful, the peak image intensity must be normalized to the peak intensity that would be found with an unaberrated version of the same optical system. An optical test bench apparatus which performs a properly normalized measurement of the peak intensity in an image of a sub-resolution aperture is disclosed.

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Apparatus for Evaluation of Lenses by Direct Measurement of The Normalized Value of the Peak Intensity in the Point Spread Function (Strehl Ratio)

       The peak intensity in the image of an infinitesimal
object is an excellent measure of the image quality provided by an
optical system.  To be useful, the peak image intensity must be
normalized to the peak intensity that would be found with an
unaberrated version of the same optical system.  An optical test
bench apparatus which performs a properly normalized measurement of
the peak intensity in an image of a sub-resolution aperture is
disclosed.

      The optical image of a hypothetical object having infinitesimal
dimension is called the point spread function (PSF).  The maximum
intensity in the PSF of an optical system, divided by the maximum
intensity that would be found if the system were free of aberrations
(an ideal system), is referred to as the Strehl Ratio (SR).

      In theory, the SR is a sensitive measure of the quality of a
high resolution optical system.  It is widely used in theoretical
analyses of optical designs.  The difficulty in implementing a lens
evaluation based on SR is that the peak intensity in the PSF of the
unaberrated optics must be available to normalize the data.  Because
a real system under test cannot be rendered aberration free, it has
been argued that the SR cannot be measured.  No solutions to this
problem have been proposed, and there are no reports of direct
measurements of SR.  A lens te...