A Low Cost, Low Temperature Radiometer for Thermal Measurements

摘要

We have developed an inexpensive, compact radiometer for in situ measurement of low levels of flux in the far infrared. It utilizes a Winston cone fabricated cheaply using a boring tool and standard commercial thermometers as sensors. Its form is similar to bolometers which have long been used for sensitive astronomical infrared measurements. By relaxing the sensitivity and response times the radiometers can be made much less costly. The sensitivity varies with the operating temperature, but at 20 K the measured resolution is better than 0.01 microwatt per cm2, equivalent to the heat from a low emissivity blanket at 30 K or a high emissivity surface at just 1 K hotter than the radiometer held at 20 K. The Winston cone provides a directional signal, excluding sources that are outside the acceptance cone (11 degree half-angle in this case) by more than a factor of 1000). The intended use is to measure the in-situ properties of aluminized Kapton at low T and to look for heat leaks and reflected flux in low temperature thermal vacuum systems.