<title>Compact holographic imaging spectrograph for process control applications</title>

Abstract

A novel spectrograph configuration, ideally suited for process control applications, is discussed. The configuration, referred to as axial transmissive, consists of axially-symmetric refractive optics and a volume phase holographic transmission grating. The axial transmissive spectrograph is veiy compact and robust, featuring no moving optical elements. This configuration also results in very high spatial resolution, allowing a large number of different processes to be monitored simultaneously on a single two-dimensional array detector. Results are presented for experiments, performed using the axial transmissive spectrograph with a laser, fiber optic sampling, and a multi-channel CCD detector, that are representative ofprocess control applications.