The invention relates to an apparatus for radiant thermal development of photothermal film comprising a receiving chamber for a film cartridge, drive means to advance thermal film from said film cartridge and rewind film into said film cartridge, an accumulator to gather said film after it has left the cartridge, a source of radiant energy, a guiding means to guide said radiant energy to develop said thermal film as said thermal film passes between said cartridge and said accumulator, a radiant energy absorbing material incorporated into said photothermal film, and a lighttight container for said chamber, heater, and accumulator.