Abstract: A verification system for capsules, tablets and the like includes a test block having a slot through which the capsules are directed by a conveyor. The test block includes first and second spaced sensing planes each having bifurcated fiber optic input and output arrays on the top and both sides of the slot. An optical system provides a planar light beam for sensing the position of the capsules being tested at the output from the test block. The length of the capsule is determined from the speed of the conveyor and the time of interruption of planar light beam. If the capsule is not of the proper colors and length, it is pneumatically ejected into a rejection chute.

Abstract: The spacing between two surfaces such as the space between a glass disk and a magnetic head or slider is measured by directing light from a broad spectrum light source onto the two surfaces, and combining the reflected light, with the light at different frequencies being combined constructively and destructively. The combined signals are analyzed at a large number of wavelengths to give a plot of intensity vs. wavelength, and the wavelength or wavelengths of maximum intensity (and constructive interference) and/or minimum intensity (destructive interference) are identified. For a glass disk and a metal slider with normal incidence, the light intensity minima occur at d=(1/2)nL and maxima at d=(1/2) (n-1/2) L, where d is the separation, L is the wavelength and n is a positive integer indicating the order. The actual plot of intensity vs. wavelength is correlated with the theoretical intensity vs.