Microdensitometers,

Abstract

The photometric fidelity of the optical system of microdensitometers is compared to that of flying -spot scanning devices. Microdensitometers, which were originally developed to study fine structure of silver halide photographic images, move the object plane through a fixed, Koehler -illuminated dual projection optical system that controls scattered light and ensures uniform photometric response everywhere on the scanned area. Flying -spot and video -based scanners now being applied to photographic photometry are optical reciprocals of one another. They operate on a critically -illuminated image of the film similar to that produced by a camera, and therefore require precautionary measures to limit errors from flare light and their inherent lack of spatial stationarity. The low inertia of such systems permits high data -sampling speeds with the possibility of preprogrammed or adaptive scans under computer control. Advances in stage design, however, now allow microdensitometer optical systems also to sample at photon noise limited rates. One such microdensitometer, a spiral-scanning EDP Scanning Microscope, is described and examples of its real-time -processed density displays ( "isophote plots ") and computer interfaces are given.images the lamp filament into the aperture of the condenser; a 226 OPTICAL ENGINEERING -NOV /DEC 1973 ABSTRACTThe photometric fidelity of the optical system of microdensitometers is compared to that of flying-spot scanning devices. Microdensitometers, which were originally developed to study fine structure of silver halide photographic images, move the object plane through a fixed, Koehler-illuminated dual projection optical system that controls scattered light and ensures uniform photometric response everywhere on the scanned area. Flying-spot and video-based scanners now being applied to photographic photometry are optical reciprocals of one another. They operate on a critically-illuminated image of the film similar to that produced by a camera, and therefore require precautionary measures to limit errors from flare light and their inherent lack of spatial stationarity. The low inertia of such systems permits high data-sampling speeds with the possibility of preprogrammed or adaptive scans under computer control. Advances in stage design, however, now allow microdensitometer optical systems also to sample at photon noise limited rates. One such microdensitometer, a spiral-scanning EDP Scanning Microscope, is described and examples of its real-time-processed density displays ("isophote plots") and computer interfaces are given.

Evaluating the efficient of imaging processes

“…The principles of microdensitometry have been reviewed by Dainty and Shaw (1974), complete with bibliography. Recent papers describing the design of advanced microdensitometer systems include those by Grimes (1971), Swing (1972Swing ( , 1973, Kinzly (1972, 19473), Kofsy et a2 (1972), Reynolds and Smith (1973), Cronin and Reynolds (1973), Fallon (1!273), Miller et al (1973), Johansson and Biedermann (1974b) and Biedermann and Johansson (1975).…”