A 635-nm solid-state laser diode module with 25-mW output is available from Blue Sky Research. The ChromaLase 635 has proprietary beam-collimating optics that generate a circular, diffraction-limited, low-divergence beam. It includes a TE cooler and integrated 5-VDC power supply, drive and control electronics. A potentiometer on the rear of the module enables variable power control. Measuring 38 X 158 mm, the cylindrical module can be directly mounted to circular, square or standard 44.5-mm HeNe laser holders.