Method and apparatus for measuring total specular and diffuse optical properties from the surface of an object

摘要

A portable device for measuring total reflectance from the surface of an object by means of electromagnetic radiation has a housing defining an ellipsoidal chamber having a reflective interior surface, a first focus, an opposite second focus. The chamber defines a first aperture at the first focus, the first aperture being adapted for placement against the surface of the object so that a portion of the surface is in optical communication with the chamber. A light source illuminates the portion of the surface of the object through the first aperture with the electromagnetic radiation of a predetermined waveband, such as infrared. A means for measuring the radiation is disposed adjacent the second focus, so that when the first aperture is placed against the object, the electromagnetic radiation illuminates the object in an area adjacent the first focus. The reflected radiation, both specular and scattered, is directed by the interior reflective surface to the radiation measuring means. Disposed between the first focus and the second focus is a means for reflecting substantially all of the electromagnetic radiation from the source of focused radiation to the radiation measuring means, thereby providing a reference beam to the radiation measuring means. The ratio of the intensity of the light reflected off of the surface of the object to the intensity of the reference beam provides an indication of the absolute reflectance of the object. Also disclosed is a coating for transducing light into infrared light.