Chromatic Aberration: Chromatic aberrations are a function of the dispersion characteristics of optical materials. There are two forms of chromatic aberration: longitudinal aberrations which result in different focal points for different wavelengths and transverse aberrations which cause different magnifications for different wavelengths.
Collimating Lens: A collimating lens system is designed to image a point light source in such a manner that all the emerging rays are parallel to each other. Collimation is a general term for the imaging of a focal point at infinity.
Condenser Lens: A condensing system is designed to collect light emitted by a light source as efficiently as possible and transfer that light to an object point or plane.
Contrast: Contrast is a general term used for differences in brightness or color. There are two types of contrast: Photometric contrast which is the difference in brightness between two luminous surfaces and physiological contrast which is the difference in brightness or color as seen by the eye. Note: Contrast in the context of transfer function is termed modulation or MTF.
Depth of Field: Depth of field is a term used for the distance range that an acceptable focus is obtained.
F-number (F/N): F-number is the radio of the focal length to the entrance pupil diameter of an imaging system. |