Patent ID: 6147761
Filing Date: 2000-11-14
Classification: G01J

Abstract:
A sensor for sensing reflective, spectrophotometric, densitometric, colorimetric, self-luminous or radiometric characteristics of a sample, comprising:a base having a lower surface;a plurality of light sources respectively emitting light of a substantially different wavelength band, mounted to said base such that a first portion of light emitted by said light sources transmits below said lower surface of said base;a sample photodetector; anda first optical assembly, mounted to said lower surface of said base, said first optical assembly being configured to direct said first portion of the light to the sample while excluding direct transmission of said first portion of light to said sample photodetector and being further configured to direct a portion of light reflected from the sample to said sample photodetector;said first optical assembly includes an annular collar mounted to said lower surface of said base and positioned over said plurality of light sources and over said sample photodetector, said collar including a plurality of emitter apertures extending axially therethrough, each emitter aperture being provided for a corresponding one of said light sources, and said collar includes a receiver aperture extending axially through said collar so as to provide optical communication between the sample and said sample photodetector;said emitter apertures being arranged about said sample photodetector;said first optical assembly further including a reflector cone, said reflector cone including a central axis, a hollow cavity, a tip, and a focal aperture in said tip, said focal aperture providing optical communication into said hollow cavity;said reflector cone extending from a lower surface of said collar;said focal aperture and said receiver aperture being coaxially aligned on said central axis;each of said emitter apertures including an emitter axis;said reflector cone including a frustoconically shaped reflective inner surface, coaxially aligned with said central axis and positioned to intersect with each of said emitter axes; andsaid reflective inner surface of said hollow cavity being angled inwardly toward said central axis at an angle so as to direct said first portion of light emitted by said light sources towards said focal aperture at substantially a 45.degree. angle with respect to said central axis;whereby, when said focal aperture is placed on a sample surface said first portion of light emitted by said light sources is reflects off of said inner surface of said hollow cavity, and is directed toward the sample surface at substantially a 45.degree. angle, and reflects off of the sample surface at substantially a 45.degree. angle, and said sample photodetector receives a diffuse component of said light reflected off of the sample surface.