Bolocam represents a great improvement in both sensitivity and mapping speed for millimeter-wavelength photometry. The camera is close to the limit of the number of detectors that can be implemented without a cold multiplexer. New technologies such as gallium-arsenide FETs and Transition-Edge Superconducting (TES) bolometers with SQUID readouts are being pursued for subsequent generations of Bolocam, and are expected to operate with a million times lower power disappation than the present cold readout.
The cryogenic design of Bolocam is optimized to reduce the cost and complexity associated with operating detectors at sub-kelvin temperatures. A large liquid helium tank that is not pumped in operation reduces the consumption of expensive liquid helium, as well as the amount of time spent preparing the system for operation. Operation of the final 300 mK system will be automated, allowing untrained observers to use the system safely and efficiently. We will continue to refine the cryogenic design. In the future a 4K mechanical cooler may be installed to reduce liquid helium consumption during off-line periods. The multi-stage 4He/3He sorption fridge is also being redesigned. We are testing a 4-cycle 4He/3He/3He system developed by Simon Chase for the Polatron experiment at Caltech.