We present experimental evidence that demonstrates a greatly increased depth of field in a broadband-illuminated imaging system through the use of a special-purpose phase mask and digital filtering. The phase mask is of a simple rectangularly separable cubic-phase design, whereas the digital filtering used was a simple object-independent least-squares inverse filter. We demonstrate successful operation of the system over a range corresponding to 30 times the Hopkins criterion for allowable misfocus.
© 1996 Optical Society of America
Original Manuscript: January 29, 1996
Published: July 1, 1996
Joseph van der Gracht, Edward R. Dowski, Merwyn G. Taylor, and Dawne M. Deaver, "Broadband behavior of an optical–digital focus-invariant system," Opt. Lett. 21, 919-921 (1996)