In-line anamorphic beam expanders

The conventional method of producing fingerprints by total internal reflection using a right-angle prism does not give true size images. In this case an anamorphic real image is formed by the Scheimpflug condition with keystone distortion. A method of combining a single prism with the right-angle prism for anamorphic stretching to get the correct fingerprint image is described. The method of constructing such a type of an optical system is discussed in detail. The method is useful to directly obtain the correct fingerprints using a CCD camera.

Method for producing correct fingerprints.

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Characterization of Laser Beams: The M2 Model

Comments on: Efficient Generation of Laser Beams with an Elliptic Cross Section.

Stainless steel chopper wheel

There frequently exists a need in holographic and other coherent-optic research for a laser beam that does not have a circular cross section. For example, if rectangular holograms are to be recorded or if rectangular object transparencies are to be illuminated, the usual circular cross section laser beam, e.g., TEM00 mode, cannot be efficiently utilized. This note describes a simple, straightforward technique for generating a clean laser beam with an elliptic cross section. A single prism can convert a light beam with a circular cross section into one with an elliptic cross section. Referring to Fig. 1, one sees that if an incoming beam of width w is normally incident upon the first surface of a prism of refractive index n and apex angle 0, after refraction at the second surface, it will have a new reduced width w', where

T. E. Gayeski

Papers

Efficient Generation of Laser Beams with an Elliptic Cross Section