Purpose of Entrance Slit in Spectrometer: Rgds Evidenso

[evidenso]

Hi
Can anyone tell me the purpose of a entrance slit in a dispersive spectrometer. What is it good for? I guess it will create a single slit diffraction pattern. Why will this make the resolution better, instead of just colliminate the beam?

Will the slit do some kind of Fourier filtering also?

Rgds
Evidenso

 

[fleem]

The slit should not be so small that there is notable diffraction from it. Its purpose is simply to make the spectral lines narrow. Consider that even monochromatic light entering a prism at a different spot will be projected at a different spot. So the slit keeps it to one spot.

 

[Andy Resnick]

An entrance slit is not a requirement, but it's true that many spectrometer designs (Echelle, use entrance slits.

One reason is overall transmission efficiency and aberration correction- some designs are kinda like imaging systems in that the exit slit is an image of the entrance slit.

Another reason is so that multiple spectrometers can be daisy-chained together to provide ever-finer spectroscopic detail.

Chapter 8 of the Richardson Grating Handbook has addtionial details:

http://gratings.newport.com/handbook/handbook.asp

 

[evidenso]

An entrance slit is not a requirement, but it's true that many spectrometer designs (Echelle, use entrance slits.

One reason is overall transmission efficiency and aberration correction- some designs are kinda like imaging systems in that the exit slit is an image of the entrance slit.

Another reason is so that multiple spectrometers can be daisy-chained together to provide ever-finer spectroscopic detail.

Chapter 8 of the Richardson Grating Handbook has addtionial details:

http://gratings.newport.com/handbook/handbook.asp

Hi
Thanks, very helpful.