Abstract: A volume diffraction grating having a substrate and an optically active layer has a structure formed in the optically active layer. The structure is operational to diffract optical signals in two selected spectral bands. The grating may be formed in a high dispersion embodiment suitable for separating individual signals from composite signals of both spectral bands. Alternatively, the grating may be formed in a low dispersion version which can separate the composite signals from each other. In another embodiment, a second structure is formed in the optically active layer. Each of the structures is configured to be operational in one of the spectral bands, allowing signals in each band to be diffracted independently of one another. In another embodiment, the structure(s) may have a curved profile allowing the diffracted beams to be shaped or focused without the need for external lenses.

Abstract: A light measurement device that selectively operates in a normal light measurement mode, in which the output from a sensor cell is logarithmically compressed and directly output as an output, or an integration light measurement mode, in which a signal obtained by integrating the output with an integrating circuit is output. In the integration light measurement mode, since the integrated output can be slowly read out after strobo light emission, accurate light measurement can be performed within a predetermined light measurement time even when the number of divisions of the sensor is increased.

Abstract: An apparatus for evaluating performance of a test endoscope includes a plurality of light sources, each generating a respective beam of light which is transmitted through the test endoscope. The apparatus further has a grid formed with a plurality of evenly spaced and uniformly sized pinholes intercepting a beam of light. The grid is utilized to perform a field of view, image quality, distortion, depth of field and an angle of view tests of the test endoscope. The apparatus further has a fiber optic light guide having one of its ends bifurcated and designed so that the bifurcated ends have the same output for evaluating light transmission through the test endoscope.

Abstract: An optical filter used in applications involving spectroscopic measurements is fabricated by depositing layers of optical coatings onto a substrate. The layers are deposited so as to have a substantially constant thickness in a first direction along the surface of the substrate, and a gradually increasing thickness along a direction perpendicular to the first direction. The structure of the optical filter allows for large scale production of the filter so that costs in producing the filter are greatly reduced. The filter may be used in a variety of applications including, but not limited to chemical analysis, blood glucose monitoring, and the like.

Abstract: An external calibration system for a photo multiplier tube is described. The calibration system uses a light emitting diode and a photo cell wherein the diode is domed shaped. The light sensitive face of the photo multiplier tube is contained in the plane disposed at an acute angle to the longitudinal axis of the light emitting diode, and the photo cell is mounted substantially perpendicular to the longitudinal axis. A source of electrical energy then illuminates the light emitting diode over a range from, for example, 0 to 5 volts to generate light of known intensity and the light being generated is simultaneously measured by the photo cell and the light sensitive face of the photo multiplier tube. A feedback circuit is provided and associated circuitry so that a number of readings can be taken over a wide variety of light intensities to generate a calibration for the photo multiplier tube.

Abstract: An automatic tilt angle compensator, which comprises a sealed container for sealing at least two types of liquids to form a free interface, a light projecting system arranged to project a light beam through the free interface, an entry window for allowing the light beam to enter, reflecting means for reflecting the light beam after passing through the free interface, and an exit window for irradiating the light beam from said sealed container, wherein said entry window, said reflecting means and said exit window are always in contact with said liquid, and when the system is laid down by 90 degrees, the free interface is rotated by 90 degrees, and the light beam passing through the free interface is irradiated through the exit window in the same manner as before the rotation by 90 degrees.