Matched Sample Differential Laser Calorimetry

Thermocouple laser calorimetry was developed to allow absolute measurement of very small optical absorptions in materials to be used for high power laser optics. The technique involves sending a beam of light through the sample to be studied and, by means of an attached temperature sensor, measuring its change in temperature due to light energy absorption. The temperature change is measured relative to a reference object which is not exposed to the light. Sensitivities to absorptions as small as 10-5 cm-1 are possible. Photoacoustic detection of the absorbed energy allows relative measurements of absorption and when calibrated against thermocouple measurements yeilds similar absolute sensitivities.