Apparatus and method for grazing angle measurement

A method of calculating a spectral hemispherical reflectance for a sample, the method comprising:

• emitting a beam of light from a laser;
• directing the beam of light with a series of reflective elements through an elongated slot defined by a hollow sphere between a plurality of predetermined angles of incidences striking a sample at each of a plurality of different predetermined rotational positions about a sphere axis extending through a center of the hollow sphere;
• collecting a plurality of reflectance data sets corresponding to each of the plurality of predetermined angles of incidence striking the sample at each of the plurality of different predetermined rotational positions of the hollow sphere with a spectral hemispherical reflectance detector;
• and
• calculating the spectral hemispherical reflectance for the sample based on the plurality of reflectance data sets.

A non-transitory computer readable medium embodying programmed instructions which, when executed by a processor, are operable for performing a method comprising:

• emitting a beam of light from a laser;
• directing the beam of light with a series of reflective elements through an elongated slot in a hollow sphere between a plurality of predetermined angles of incidences striking a sample at each of a plurality of different rotational positions about a sphere axis extending through a center of the hollow sphere;
• collecting a plurality of reflectance data sets corresponding to each of the plurality of predetermined angles of incidence striking the sample at each of the plurality of different rotational positions of the hollow sphere with a spectral hemispherical reflectance detector;
• and
• calculating a spectral hemispherical reflectance for the sample based on the plurality of reflectance data sets.