title: Time-resolved spectroscopy using a chopper wheel as a fast shutter.
abstract: Widely available, small form-factor, fiber-coupled spectrometers typically have a minimum exposure time measured in milliseconds, and thus cannot be used directly for time-resolved measurements at the microsecond level. Spectroscopy at these faster time scales is typically done with an intensified charge coupled device (CCD) system where the image intensifier acts as a "fast" electronic shutter for the slower CCD array. In this paper, we describe simple modifications to a commercially available chopper wheel system to allow it to be used as a "fast" mechanical shutter for gating a fiber-coupled spectrometer to achieve microsecond-scale time-resolved optical measurements of a periodically pulsed light source. With the chopper wheel synchronized to the pulsing of the light source, the time resolution can be set to a small fraction of the pulse period by using a chopper wheel with narrow slots separated by wide spokes. Different methods of synchronizing the chopper wheel and pulsing of the light sources are explored. The capability of the chopper wheel system is illustrated with time-resolved measurements of pulsed plasmas.
authors: Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors: Shicong
authors: S
authors: Wang
authors: Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors: Amy E
authors: AE
authors: Wendt
authors: Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors: John B
authors: JB
authors: Boffard
authors: Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors: Chun C
authors: CC
authors: Lin