Versatile, High Accuracy Scan Lens Test Bench

A scan lens test bench must be adaptable to the wide range of sizes, formats, and wavelengths of scan lenses manufactured today. In addition, it's metrology must be capable of accurately measuring angles and distances for verification of scan linearity. All of the above were carefully considered in the design and fabrication of this bench. Fringe counting interferometry is employed for monitoring linear and angular motions. Attached to a fringe counter via a tangent arm, a flat mirror, pivoting at the test lens' entrance pupil location, is used to accurately deflect the input beam to the desired scan angles within a few seconds of arc. Since the beam deflection is produced with the pivoting mirror, the laser and beam expander optics are stationary. Therefore, virtually any laser and beam expander can be adapted to the setup. This simplifies the selection of desired wavelengths and input beam sizes. Adapter plates facilitate mounting of lenses having a wide range of sizes. Long precision linear slide motions are used to accommodate larger format lenses. The design, fabrication, alignment, and use of this test bench will be discussed.