Synopsys Command : Clear Command Window
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Chief Ray
From an object point light rays spread cone shaped in the direction to the rim of the entrance Pupil and later from the direction of the rim of the exit pupil to the image point.
The chief ray is the axis of those cones and contains the center of the Entrance Pupil and the center of the mechanical iris.
See Chief Ray Angle
Cine-Mount
see = c-mount
Cine-Short-Mount
= CS-Mount
Circle Of Confusion
Images of point size Objects would ideally be points. For physical reasons (“diffraction”), we only obtain little disks of light.
The so called circle of confusion (also called “Airy disk”) is the smallest disk of light, that an ideal lens can theoretically generate on image side.
The smallest possible diameter of a circular disk that a “perfect” (=diffration limited) lens can generate on image side is given by the Rayleigh Criterion.
Contrast
The optical term “contrast” of an image is pretty much what we would expect from our daily use of the word.
However, we have to distinguish global contrast …
… from local contrast :
The global contrast in the two images above is about the same, however the local contrast (the change from pixel to pixel) is less high in the lower image, because of the slight blurring.
The local contrast is described by the MTF-curve.
Yellow Writing on a white paper is nearly invisible on the image of a monochrome camera. Illumination with blue light increases the contrast nicely.
- Weber contrast
(Feature -background) / background - Michelson contrast
Difference of intensities divided by sum of intensities. Often used in image processing. - RMS contrast (Root Mean Square Contrast)
Standard deviation of the pixel intensities.
CRA
Angle between the (usually image side Chief Ray and the optical axis
critical angle
Critical Aperture
CS-Mount
Standardized interface for the mounting of lenses, described in ISO 10935 (1996-12) Optics and optical instruments – Microscopes – Interface Type CS
The diameter of the thread is 1 “(one inch) and there are 32 threads to 1” in length.
The distance between the mechanical stop of the lens and the sensor in cross bolts in air is 12.52 mm. These are about 5mm less than for C-mount lenses.
C-mount lenses can (with an 5mm extension (C-CS-mount adapter)) be used in CS-mount cameras,
However CS mount lenses can not be used in C-mount cameras.
CS-Mount lenses are mostly used in security systems, often these are wide-angle lenses.