Abstract: A coaxial optical fiber bundle assembly (Reference No. 6 in the following Specification and Drawing), carrying emitted light from a light source and received light which has been returned by an object illuminated from said light source, is moved towards the object (Reference No.: 7) to cause the intensity of the received light, as detected by a photo transistor in light emitter-receiver unit (Reference No.: 1), to attain a maximum value which is amplified and held as a display on digital voltmeter (Reference No.: 11). Comparison of the held value with the corresponding held maximum value resulting from a similar determination made of either a different object of the same object after a color change therein or thereof can thus be made on a numerical basis.

Abstract: Measurements of the greasiness of skin are made by applying a plate against a region of skin to be studied and then inserting the plate in a recess of the casing, in register with a photodiode and a phototransistor. A series of n (in this case 5) indicator lamps is connected to a set of n-1 (in this case 4) comparators each comparing a respective voltage threshold level with the voltage delivered by the photoresistor, so that the voltage of the transistor, and hence the greasiness of the deposit on the plate through which luminous flux from the photodiode to the phototransistor passes by reflection from the upper side of the plate, can be determined by observing which lamps are illuminated.