(under subclass 337) Subject matter wherein the correction is accomplished by allowing light transmission through the filter of an input light beam only after a particular amount of energy is either applied (saturable filter) or a specific portion of the light beam is passed (spatial filter).
(1) Note. A saturable filber is opaque to a light beam input until one of the atoms of its material is excited to a second energy level as a result of striking photons. Upon reaching this second energy level, the filter becomes "saturated" and thus transparent to the input beam due to the equalization between the original and second energy levels causing no net absorption of additional photons as they strike the filter.
(2) Note. A spatial filter generally consists of either (a) an emulsion mask having a clean annular region in an otherwise opaque region or (b) a pinhole, placed at a focal plane in a laser expander; to remove unwanted radiation generally referred to as amplified spontaneous emission.
SEE OR SEARCH CLASS
372, Coherent Light Generators,
11, for absorption filter Q-Switch and subclass 14 for mechanical spatial filter Q-Switch.
