Abstract : The design of a radiometric experiment is described which provides a laboratory model for implementation of the optical correlation technique. The radiometer has provision for alternately viewing the source directly and through a gas absorption cell. The source may be characterized either by unstructured continuum or by specific molecular emission. Optimization of the gas cell parameters (temperature, pressure, etc.) is sought for maximum discrimination between molecular and blackbody emission. The cell is 10 centimeters in length and may be operated up to two atmospheres in pressure. A double pass may be made by the replacement of one end window with a mirror. The detector bandpass is limited by optical filtering. The desirability of an advanced molecular absorption band model for highly non-isothermal paths and further absorption- emission spectraradiometric data are discussed.