Patent ID: 8194125

Claim:
A radiance source comprising: a housing having an interior wall, wherein at least a spherical portion of the interior wall of the housing is spherical, an interior volume, and an exit port; a light source disposed within the interior volume of the housing and supported from the interior wall of the housing; a calibration structure disposed to block and reflect a light ray that would otherwise travel directly from the light source to the exit port without reflecting from the interior wall, wherein the calibration structure comprises a calibration body having a curved back surface facing the light source and a curved front surface facing the exit port, wherein a radius of curvature of the curved back surface is larger than a radius of curvature of the curved front surface, a support positioning the calibration body relative to the exit port and to the light source; an optically diffuse reflecting surface on at least the spherical portion of the interior wall of the housing, the back surface of the calibration body, and the front surface of the calibration body; wherein the housing comprises a first chamber containing the light source, a second chamber containing the calibration structure, and a transfer aperture extending between the first chamber and the second chamber.