ISSN Online: 2377-424X
International Heat Transfer Conference 12
Design and characterization of a bidirectional reflectometer
Sinopsis
In a rapid thermal processing system, the radiation environment can greatly affect the reading of a lightpipe
radiation thermometer. Knowledge of the bidirectional reflectance distribution function (BRDF) of rough silicon
wafers is needed for the prediction of the reflected radiation into the lightpipe, so that it can be used for accurate temperature measurement. A new bidirectional reflectometer is designed that allows measurements of out-of plane scattering distributions and for samples at elevated temperatures. The incidence angles range from 0° to
88°. The viewing polar angles cover from 0° to 90° and the azimuthal angles, relative to the incidence direction, range from 0° to 180°. Three laser diodes at wavelengths of 635, 785, and 1550 nm are employed. Silicon and germanium photodiode detectors are used. Measurements of the bidirectional transmittance distribution function (BTDF) can also be made at the wavelength of 1550 nm when silicon is transparent. Initial measurement results
of polished and rough silicon wafers are presented and compared to the theoretical models.