Wavelength measuring instrument for optical lasers - has reflector and rotatable mirror at focal points of elliptical mirror

摘要

The optical wavelength measuring instrument esp. for laser radiation, consists of a reflecting screen (4) placed at one focal point of an ellipse (2) onto which a laser beam (8) impinges. The emerging rays pass through an aperture (12) to a concave mirror (5) at the far end of the ellipse. The elliptical surface of the mirror causes the separate paths (13-15) to converge at the second focal point of the ellipse (3). At this point, a plane rotatable mirror (6) can be turned through an angle corresponding to a certain wavelength. The reflected ray is then detected by a photo-electric sensor (7) which can be moved around an arc on the focal line of the ellipse so that maximum signal intensity corresponds to the spectral centroid of the light under investigation. The angle of rotation of the plane mirror can be transformed into an electric signal to drive an analogue or digital display of the wavelength.