公开(公告)号：CA2143900A1

公开(公告)日：1996-09-04

申请号：CA2143900

申请日：1995-03-03

Applicant: UNISEARCH ASSOCIATES INC

Inventor： ROBBINS JOHN ,  NADLER SHACHAR

IPC: G01J3/02 ,  G01J3/04 ,  G01J3/28 ,  G01J3/32 ,  G01J3/42

Abstract: An apparatus for use in Differential Optical Absorption Spectroscopy (DOAS) or in other optical apparatus provides a moveable or oscillating aperture. It has a sensor for detecting the position of the aperture, and a drive for oscillating the aperture; the drive and sensor can comprise coils forming a linear variable differential transformer, and the aperture can be spring biased to a neutral position. A control circuit is connected between the coil or other sensor and the drive coils, so that the motion of the aperture follows a desired profile. This enables significant parts of the apertures motion to be constrained to be linear. The aperture can be provided in a shuttle mounted on extension arms, whose ends are connected to resilient biassing means which serve both to support the shuttle and to bias it. More preferably, extension arms extend through pole pieces of magnets, which provide a magnetic field for drive coils. Another aspect of the invention provides a telescope apparatus, for a DOAS technique, including a baffle moveable between calibration and operational positions. This enables light from the light source to be transmitted either for measurement or for calibration allowing for changes in lamp output, etc.