Surface contamination detection using infrared-transparent fibers or

Abstract

Airborne contaminants within a substantially sealed enclosure are detected and measured, in situ, without interrupting the operation of moving parts within the enclosure. At least one infrared (IR)-transparent attenuated total reflection (ATR) element, such as an optical fiber, optical fiber bundle, or ATR crystal, is disposed in the enclosure to collect or react with contaminants. An IR source is optically coupled to one part of the element, and an IR detector is optically coupled to another part of the element. The source and detector, in combination, respond to changes in intensity at the wavelengths of the IR radiation transmitted by the element to identify the contaminants and quantities thereof that settle on the element or compounds that have formed thereon. The source may be a continuous source (such as a black body) and the detector an IR spectrometer. Or, the source may be a diode laser and the detector an IR radiation detector. The sealed enclosure may be the housing of a head-disk assembly of a disk file. Atlernatively, the apparatus may include an IR-transparent ATR element disposed within the housing and an IR spectrometer optically coupled to a radiation output surface of the element for sensing emission emerging from the element. One end of the element may be reflection coated to increase the radiation output.