The Spectroscopy Net
Gateway to Spectroscopy > Spectrometers > Polychromators


A polychromator's performance depends on essential features such as brightness, stability, spectral purity and resolution.

Schematic Polychromator

A polychromator can be mounted with two gratings as shown below, with the second grating taking its light from the zero order diffraction (direct reflection) of the first grating. The photomultipliers can be mounted in different veritical and horizontal positions using mirrors and filters and other optical devices to optimise space. An example of the inside of a polychromator with a 1 metre focal length for high resolution is shown below:

1m Polychromator

Inside the circular spectrometer, light enters from the top on the left hand side, the grating is mounted inside the bottom left hand side, and the photomultiplier tubes are mounted on the Rowland circle near the top and right hand side.

First published on the web: 15 May 2000. Last modified: 20 November, 2007

Author: Richard Payling