Thermal processor employing radiant heater

A method of operating a thermal processor for thermally developing photothermographic film, comprising:

• providing a rotatable hollow drum including a drum core having an interior surface and an exterior surface;
• providing a radiant heater positioned within an interior of the drum and configured to provide radiant energy to heat the drum;
• and
• varying at least one radiant energy absorption characteristic of the interior of the drum across its longitudinal width whereby selected areas of the interior of the drum absorb more radiant energy than other areas of the interior of the drum to compensate for non-uniform heat loss from the drum and to provide the exterior surface of the drum core at a desired temperature which is substantially uniform across a longitudinal width of the drum core, wherein the at least one radiant energy absorption characteristic comprises an emissivity of the interior surface of the drum core, and wherein the emissivity of the interior surface of the drum core varies across the lateral width of the drum core;
• wherein the emissivity is greater at end portions of the interior surface of the drum core relative to a middle portion of the interior surface of the drum core;
• and wherein the end portions of the interior surface of the drum core are coated with a material that increases the emissivity of the end portions relative to the interior surface of the middle portion of the drum core.

A method of operating a thermal processor for thermally developing photothermographic film, comprising:

• providing a rotatable hollow drum including a drum core having an interior surface and an exterior surface;
• providing a radiant heater positioned within an interior of the drum and configured to provide radiant energy to heat the drum;
• varying at least one radiant energy absorption characteristic of the interior of the drum across its longitudinal width whereby selected areas of the interior of the drum absorb more radiant energy than other areas of the interior of the drum to compensate for non-uniform heat loss from the drum and to provide the exterior surface of the drum core at a desired temperature which is substantially uniform across a longitudinal width of the drum core;
• and
• providing a temperature sensor mounted to and extending about a circumference of the interior of the middle portion of the drum core, the temperature sensor being coated with a material having an emissivity less than an emissivity of the interior surface of the middle portion of the drum core.