A temperature-controlled blue-violet laser diode module for OEM applications is available from Power Technology Inc. The PPM emits 400-nm light from a 5-mW laser diode that operates at 20 °C, thanks to its thermoelectric cooler. The temperature coefficient is 0.5 nm/°C. The diode operates in either automatic power control mode or constant current mode. Its spectral width of 1 nm makes it suitable for many applications, including fluorescence, spectroscopy, medicine, display, interferometry and microscopy.