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A radiation calorimeter for measurement of optical properties, such as absor - ptivity and emissivity, of materials for the purpose of thermo - radiation process studies, has been designed and constructed. The apparauts consists of two similar cavities where two samples under comparison are held by glass rods. The cavities, with polished thick aluminum walls and convex glass covers, can be evacuated so that the heat transfer to and out of the samples is practically limited to radiation processes.
The particular design featurs are;
1. High thermal capacity of the cavity walls makes them to remain practically at room temperature during a measurement which normally takes a few minutes.
2. The samples are held in similar positions.
3. Irradiation is nearly uniform over the sample surface.
4. There is no heat transfer between the samples under comparison.
These features make the heat transfer diagram for the samples fairly simple1 and accordingly the calculations are straightforward.
Test experiments carried out prouved the convenience of the use of this calori - meter.