Apparatus for measuring reflected light under stabilized light source conditions

Claim 1

Apparatus for quantitative photometric measurement of color reflectance values from a color reflectance surface which comprises in combination a polychromic light source positioned so as to direct polychromic light on such color reflectance surface, a first bundle of optical fibers having a light entrance end and a light exit end, a second bundle of optical fibers having a light entrance end and a light exit end, the portions of the first and second bundles of optical fibers near their light entrance ends being uniformly intermixed with all the fibers substantially parallel to form a single bundle of optical fibers, said single bundle having its light entrance end positioned near said color reflectance surface, a first filter means having maximum light transmission at a first selected wavelength range positioned adjacent to the light exit end of said first bundle of optical fibers, a first photosensitive means positioned adjacent to said first filter means to detect light transmitted through said first filter means, a second filter means having maximum light transmission at a second selected wavelength range positioned adjacent to the light exit end of said second bundle of optical fibers, a second photosensitive means positioned adjacent to said second filter means to detect light transmitted through said second filter means, a first amplifier connected to said first photosensitive means, a power supply connected to said first amplifier and to said polychromic light source, a second amplifier connected to said second photosensitive means and a readout means connected to said second amplifier, said first photosensitive means in combination with said power supply adjusting the output of said light source in response to a change in the reflected light from said color reflectance surface being sensed by said first photosensitive means so that a substantially constant reflected light at said first selected wavelength range is sensed by said first photosensitive means, the reflectance values from said color reflectance surface at the second selected wavelength range sensed by said second photosensitive means and indicated by said readout means thereby being directly related to specific characteristic reflectances of said color reflectance surface.