Systems, methods, and devices for integrated detector cooler assemblies (IDCAs) and multi-circuit cryostats are discussed herein. Solutions include using cryostats with multiple cooling circuits. Some cryostat variations may include a rapid cooldown circuit and a temperature maintenance circuit. In some cases, the temperature maintenance circuit may be a closed-loop circuit run by a compressor instead of an open-loop circuit run on a pressurized gas bottle/cartridge. Variations of a cryostat may also include a gas expander portion that replaces the coldfinger of typical IDCAs. Further variations of cooling circuits may include circuits that perform reverse-flow heat exchange to pre-cool incoming refrigerant and also cooling circuits that have heat bridges disposed thereon to assist in such heat exchange.