Transverse Flow Gas Lens
AEROSPACE CORP EL SEGUNDO CA LAB OPERATIONS
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The concept of a transverse flow gas lens is described. In this device, gas flows between two parallel plates which are heated or cooled so as to generate a parabolic variation of index of refraction in the region between the plates. A laser beam, propagating normal to the gas flow, can then be diverged, converged, or focused. A single module acts like a cylindrical lens. The use of two or three modules, arranged in an orthogonal manner, provides a spherical lens. Equations and tables are provided for the design of one, two, and three module configurations. The advantages of the transverse flow gas lens relative to a device with flow along the optic axis are a thermal blooming is minimized due to short residence time of fluid in laser beam, b the index of refraction profile is the same throughout each module, leading to good beam quality, and c the system is readily scaleable. However, a longer distance along the optical axis may be needed by the transverse flow lens.