Diffusing measurement window for near and mid IR multichannel sensor

摘要

A diffuse reflector of radiation in the near and mid infrared regions includes (i) an assembly that has a reflecting element and a diffusing element that is made of one or more layers of calcium fluoride, sapphire, or alumina; or (ii) a diffusively reflective surface configured as a metallic layer with a rough surface. The diffuse reflector can be incorporated into systems for measuring properties of sheet materials and particularly into optical sensors that include a measurement window configured with one or more of the diffuse reflectors that cause incident radiation from a sensor light source to be diffused and reflected a plurality of times within a layer of material before being detected by the sensor receiver.

主权项

1. An apparatus for sensing a layer of material that comprises:
a radiation source, disposed on one side of the layer of material, that directs a beam of incident near and mid infrared radiation having wavelengths of more than 5 microns into the layer of material; a radiation receiver that detects at least a portion of a reflected beam that propagates through the layer of material; and one or more members that define a measurement cell with a path for the layer of material, wherein each member includes a diffuser comprising a layer of alumina, which is translucent to the near and mid infrared radiation from the radiation source, and that is formed on a specular reflective surface, wherein the layer of alumina has a smooth side that faces and is adjacent to a side of the layer of material and wherein the measurement cell is configured to cause radiation to be reflected through the layer of material a plurality of times before being detected by the radiation receiver and wherein the diffuser does not include quartz or plastic.