This is a completely solid-state laser system for producing ~0.1mW of UV light (231.5 nm). It replaces an aging dye laser in creating laser light that helps trap and cool single ions of Indium.
Believe it or not, this qualifies as a compact laser system.
Details
The blue box is an infrared external-cavity commercial diode laser at 922 nm. It is amplified by a factor of 10 or so in power by a commercial tapered amplifier. It is then sent through two ring cavities. The first contains a KNbO3 crystal which frequency-doubles a good fraction of the light to 461 nm blue light. The blue light is frequency doubled again in the second ring cavity using a BBO cystal to the ultraviolet.
