Abstract: A hand-carriable, compact color meter for indicating proper amount of adjustment of color compensation filters interposed in the light path of a color printer for the compensation of color balance of the light illuminating a film or the slide set on the printer. The color meter includes an indicating lamp, a photocell to be exposed to the light passing through the film or slide, a plurality of optical color filters selectively disposed in front of the photocell to provide the photocell with spectral sensitivities corresponding to the spectral sensitivity of the printing paper, a plurality of fixed or variable resistors selectable in correspondence to the selection of the color filter, and an electric circuit for actuating the indicating lamp in accordance with the relationship between the output of the light measuring circuit and a reference voltage commensurate with the selected one of the resistors.

Abstract: An optical non-invasive oximeter for measuring oxygen saturation in arterial blood utilizes a light source capable of giving off light having different wavelengths, such as light in the infrared and red region, and a pair of photoelectric devices, one responding to one wavelength and the other to the other wavelength, for detecting the amount of such light transmitted through living tissue. Each photoelectric device is connected to a computing circuit which generates a signal that represents the logarithm of the quotient of the signal received from the photoelectric device divided by its direct current component. The signals from each of the computing circuits are differentiated and then divided, one by the other, to provide an indication of oxygen saturation in the blood.