TuiOptics GmbH has introduced a direct blue external-cavity diode laser (ECDL). Based on the company's DL 100 ECDL concept, the device features single-mode transverse and longitudinal output in the 400-nm region. The center wavelength is selectable between 395 and 405 nm and is coarsely tunable over 2 nm. The system provides up to 120 mW at 830 nm. Because no antireflection coating is required on the laser diode, the external-cavity diode laser system can be used with virtually any single-mode laser diode. Mode-hop-free tuning of a few gigahertz makes the diode laser suitable for use in high-resolution spectroscopy and other scientific applications where expensive frequency-doubled dye or Ti:sapphire systems are used.