Spectrophotometer apparatus with dual concentric beams and fiber optic beam splitter

In a spectrophotometer apparatus for measuring optical absorption properties of a sample material and including a light source operative to produce light over a selected wavelength spectrum, a sample cell adapted to receive a sample of material to be tested by a test component of light transmitted therethrough, a first detector operative to measure intensity of light and disposed to receive the test component after the test component has passed through said sample cell, said first detector operative to produce a first signal corresponding to the intensity of light of the test component, a second detector adapted to measure intensity of light and disposed to receive a reference component of light, said second detector operative to produce a second signal corresponding to the intensity of light of the reference component, and optical elements operative to select a wavelength band for the test and reference components, the improvement comprising a fiber optic beam splitter operative to split light from said light source into a reference component and a test component, said fiber optic beam splitter formed by a plurality of fiber optic strands arranged such that first ends thereof terminate in a common circular area with a plurality of peripheral strands located along a periphery of the circular area and at east one inner strand located centrally of the circular area, a majority of said peripheral strands having opposite end portions separated from opposite end portions of other ones of said strands and collected into a first set and the opposite end portions of other ones of said strands being collected into a second set whereby said first and second sets split said portion of light into the reference component and the test component.

A spectrophotometer apparatus for measuring optical absorption properties of a sample material, comprising:

• (a) a first light emitter operative to produce first light over a selected first wavelength spectrum;
• (b) a second light emitter operative to produce second light over a second selected wavelength spectrum different from the first wavelength spectrum;
• (c) a first array of optical elements operative to collimate portions of said first and second light into a collimated beam having an inner core comprised of first light and an outer shell comprised of second light, said outer shell surrounding said inner core;
• (d) a second array of optical elements operative to receive said collimated beam and to disperse said collimated beam into a spectral pattern;
• (e) an optical slit operative to receive spectrally distributed light from said second array to select a wavelength band at which optical absorption is to be measured;
• (f) a beam splitter operative to split light passing from said optical slit into a reference component and a test component;
• (g) a sample cell adapted to receive a sample of material to be tested, said sample cell disposed such that the test component is transmitted therethrough;
• (h) a first detector operative to measure intensity of light and disposed to receive the test component after the test component has passed through said sample cell, said first detector operative to produce a first signal corresponding to the intensity of light of the test component;
• (i) a second detector operative to measure intensity of light and disposed to receive the reference component, said second detector operative to produce a second signal corresponding to the intensity of light of the reference component;
• and
• (j) a signal comparator operative to compare the first and second signals and to produce output correlated to an amount of light absorbed by the sample material at the selected wavelength band.