Robust terahertz spectrometer configuration against scanner heads misalignment

摘要

Robust terahertz time-domain spectrometer has a reflective surface arrangement that renders the sensor insensitive to x or y displacement. The apparatus includes: (a) first scanner head; (b) a first reflective surface; (c) emitter; (d) beam splitter to yield reference radiation pulses and sample radiation pulses; (e) first reflector to reflect sample radiation pulses that have been transmitted through the sample to generate reflected sample radiation pulses that are directed towards a web; (f) second reflector that reflects the reference radiation pulses to generate reflected reference radiation pulses that are directed towards the beam splitter which in turn transmits a portion of the reflected references radiation pulses towards the web; and (g) a detector that receives (i) the reflected sample radiation pulses that have interacted with the sample a plurality of times and (ii) reflected reference radiation pulses that have interacted with the sample a plurality of times.

主权项

1. A time-domain spectroscopy apparatus, that has a continuous reference for measuring at least one property of a sample that is a continuous web having a first side and a second side, which travels in a downstream direction, that comprises:
(a) a first scanner head disposed adjacent to the first side of the web, the first scanner head having a first operative surface facing the first side of the web; (b) a first reflective surface facing the second side of the web; (c) an emitter positioned in the first scanner head that generates pulses of radiation; (d) means for splitting the pulses of radiation to yield reference radiation pulses and sample radiation pulses wherein the sample radiation pulses are directed to the first side of the web; (e) a first reflector positioned in the first scanner head to reflect sample radiation pulses that have been transmitted through the sample to generate reflected sample radiation pulses that are directed towards the web; (f) a second reflector positioned in the first scanner head that reflects the reference radiation pulses to generate reflected reference radiation pulses that are directed towards the means for splitting the pulses of radiation which transmits a portion of the reflected references radiation pulses towards the web; and (g) a detector positioned in the first scanner head to receive (i) the reflected sample radiation pulses that have interacted with the sample a plurality of times before being detected and (ii) reflected reference radiation pulses that have interacted with the sample a plurality of times before being detected.