Testing the Spectroscope

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Setting up and testing the grating/ spectrograph

This section covers the performance testing and evaluation of a spectrograph. We all like to know how our instrument should perform.

Some comments obviously are more appropriate to DIY built spectrographs, but still equally apply to evaluating the commercial instruments.

Common issues:

1. Alignment of the optical elements to the optical axis - entrance slit, mirrors (if fitted), collimator, grating, imaging lens, camera

2. Focus of the telescope to the entrance slit

3. Focus of the imaging camera to the entrance slit

4. Alignment/ focus of guide camera


1. Resolution

2. Wavelength coverage - chromatic aberrations

3. Calibration in wavelength - reference lamps

A good starting point is to enter your parameters into the SimSpec spreadsheet - this provides a first estimate of probable performance.

For transmission gratings, use the TransSpec spreadsheet.

CAOS transmission grating test 

*****under construction*****