A Calibrated Blackbody Source for Testing Next-Generation Wavefront Actuators

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Abstract:: To lower the quantum noise floor and enhance sensitivity, LIGO’s power must be increased. However, defects within LIGO’s test masses due to the thermal effects of the laser prevent this. The current solution for this is to use a thermal compensation system (TCS) which includes a ring heater adaptive optics device. The LIGO test masses react to the ring heater and are corrected to minimize scattering into higher order mode. The precision of the TCS can be improved with assurance that the thermal imaging system is accurate and that the real incident radiance profile of the test mass matches the theoretical expectations. This is tested with an in-air IR test facility consisting of a simple radiation source projecting onto a highly absorptive thin screen. With a simple heater geometry that emulates the ring pattern of the TCS adaptive optics, end-to-end of experimental data measured by an IR camera’s code is provided. The incident radiance profile of the test masses as well as the power transfer from the heater to the screen may be analyzed, and the same calibration, once validated, may be used for more complex geometries in the future.

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LIGO Document T2200206-v6