This brief ( 500 word ) article describes the general concept of wavefront coding for extended depth of field, or focus-invariant, incoherent optical systems. Experimental results of imaging with an optical/digital extended depth of field system are included.
Extended Depth of Field Through Wavefront Coding
This paper contains the theory that describes the basis of extended depth of field, or focus-invariant, incoherent optical systems. Ambiguity function based design of incoherent systems is stressed. Simulations of imaging with a standard diffraction-limited imaging system and comparison to imaging with our extended depth of field system are given.
Optical/Digital Aberration Control in Incoherent Optical Systems
A system that is insensitive to misfocus is also insensitive to some lens aberrations. Consequently, the approach of combining optical and digital signal processing system extends the normal aberration balancing of lens design to include those aberrations that can be reduced by digital signal processing, such as spherical aberration.
An Information Theory Approach to Incoherent Information Processing Systems
Information theory offers a powerful method of determining design goals for optimum spatially incoherent information processing systems. These goals can be given both a geometric and a spatial frequency interpretation. This information theory approach is applied to the three example systems of single-image, single-lens, passive range estimation, range-invariant imaging, and orthogonal passive range detection systems.
Control of Chromatic Focal Shift through Wavefront Coding
Control of chromatic aberration through purely optical means is well known. We present a novel optical/digital method of controlling chromatic aberration. The optical/digital system, which incorporates a cubic phase modulation (CPM) plate in the optical system and post processing of the detected image, effectively reduces a system's sensitivity to misfocus in general or axial (longitudinal) chromatic aberration in particular. A fully achromatic imaging system ( one which is corrected for a continuous range of wavelengths ) can be achieved by initially correcting the optical system for lateral chromatic aberration through conventional techniques. Then the axial chromatic aberration is corrected by the inclusion of the CPM plate and post processing.
Realizations of Focus Invariance in Optical/Digital Systems with Wavefront Coding
Experimental verification of an extended depth of focus system with near-diffraction limited performance capabilities. This paper can be found in Applied Optics, December 1997, vol. 36.
Applications of Extended Depth of Focus Technology to Light Microscope Systems