The optical cryostat has a top-loading helium reservoir measuring 6 in. in diameter and 48 in. deep; the inside is visible via three sets of viewports with up to 2 in. diameter. Two laser systems (dual-head Nd:YAG at 532 nm and continuous wave solid state at 473 nm) and two cameras (intensified chargecoupled device and high-speed CMOS) allow a wide range of image data, from low light images to relatively high speed video.