Patent ID: 6775003
Filing Date: 2004-08-10
Classification: G01N

Abstract:
An optical apparatus for total internal reflection (TIR) spectroscopy comprising:a transparent body having a first entrance surface for incident electromagnetic radiation, a second plane internally reflective surface for reflecting radiation transmitted from the first surface through the transparent body, and a third exit surface through which electromagnetic radiation reflected at the second surface exits the transparent body, at least one source of electromagnetic radiation, collimating means for collimating radiation emitted from the at least one source of electromagnetic radiation to at least one beam of collimated electromagnetic radiation, optical scanning means, arranged between the collimating means and the transparent body, for directing at least part of the collimated electromagnetic radiation to the transparent body so that the radiation is internally reflected at the second surface, and sequentially or continuously scanning the incident angle of the radiation at the second surface over an angular range, the illuminated area or areas having an at least substantially fixed center position, at least one detector for detecting electromagnetic radiation exiting from the transparent body, and means for varying the cross-sectional intensity of at least one of (i) the at least one beam of collimated electromagnetic radiation incident on the second plane surface of the transparent body, and (ii) the at least one beam of collimated electromagnetic radiation reflected from the second plane surface of the transparent body, in dependence of the incident angle at the second surface during the angular scan, so that the variation of the irradiance at the illuminated area or areas of fixed center position of the second plane surface due to a varying length extension in the plane of incidence of the illuminated area or areas during the angular scan, or the effect of such variation on the reflected beam or beams, is counteracted.