公开(公告)号：US3603690A

公开(公告)日：1971-09-07

申请号：US3603690D

申请日：1969-10-22

Applicant: NASA

Inventor： HARD THOMAS M

IPC: G01J3/06 ,  H01S3/081 ,  H01S3/086 ,  G01B9/02 ,  G01N21/16

CPC classification number: G01J3/06 ,  H01S3/0812 ,  H01S3/086

Abstract: This disclosure describes optical systems that have output beams that are spatially invariant to the angle of incidence upon a certain rotatable surface forming a part of the systems, and can be used to select the wavelength of the output of an optical source, such as a laser cavity, or to aid in measuring the reflectance of a material in reflectance spectroscopy. The optical systems comprise various combinations of plane mirrors and plane diffraction gratings (or sample surfaces), in some embodiments, spherical mirrors. The plane mirrors, plane gratings and spherical mirrors are either rotated or fixed in space in accordance with a particular embodiment. The moveable suitable movement mechanism, such as a micrometer. By rotating the shaft of the micrometer to a particular incidence angle, the frequency of the output of a laser cavity can be selected. Alternately, the reflectance of a material can be observed for a particular angle. In either case, the output beam remains spatially invariant as the position of the shaft and its attached elements is changed.