Optical remote measurement assembly

An optical measurement assembly for use with a pharmaceutical tablet coating machine comprising a rotating drum disposed in a housing, and a coating means adapted to apply coating material onto tablets disposed in the drum, the coating machine housing including means for circulating air for drying the coating material applied to the tablets, the measurement assembly being adapted to measure at least one of moisture in the tablet coating and coating thickness, the measurement assembly comprising:

• a processor for disposition outside of the coating machine housing and having means for providing a light source, means for receiving light from the coated tablets, and analyzer means for analyzing the received light for detecting and measuring the at least one of coating moisture and thickness;
• an optical head comprising an optical head housing for disposition in the drum, a source light mirror mounted in said optical head housing for directing a light beam onto the tablets in the drum, the beam having a central axis extending from said source light mirror, a window mounted in said optical head housing permitting light to pass therethrough, a collector mirror mounted in said optical head housing and having a central axis coinciding with the light beam central axis, and configured to receive light reflected from the tablets, a return mirror disposed in said optical head housing for receiving light from said collector mirror;
• a source light guide extending from the processor light source to adjacent said optical head source light mirror;
• and
• a return light guide extending from adjacent said optical head return mirror to said light receiving means.