rrm (01/25/83)
Can anyone help me with the following question? I've been considering constructing a spectrograph for astronomical use, but I have been unable to find hardly any information about the design of such an instrument. I would like to use a diffraction grating (transmission) for the dispersion element and I have worked out the physics of this device, so I am fairly comfortable about how it operates. Now comes my problem. Almost all of the spectrographs I've seen contain a narrow slit at the focal plane. I also believe that the resolution of the instrument is inversely proportional to the width of this slit. Can anyone help me on understanding the purpose of this slit and the direct relation it has on the design of the spectrograph?? It's been a long time since my undergrad days of physics so I'm pretty rusty on this and I don't have my old text with me so I can't look back at the optics section. I'm sure I've have some of this material ( or the background for it) back then but time has taken it's toll. I would appreciate comments from anyone on the net. Perhaps there are even some professional astronomers out there who devote their lives to this! Ron Meyer inuxa!rrm American Bell - Indy