Calculating Light Intensity in Diffraction Orders

[u0362565]

Hi,

I was wondering how you can calculate the intensity of light produced by diffraction orders. If say a laser was incident on a diffraction grating and this split the zeroth and +-1 orders what percentage of the light intensity is within the zero and first orders and how can you work this out? I'm only looking for a rough percentage figure i don't actually need to calculate exact figures, i imagine that is possible if details of the grating/laser were known..

Many thanks

 

[LoopInt]

The intensity is the square of the amplitude of the wave. Can you calculate the amplitude? If you know where the max occurs, then you can plug that in the envelop wave.
Check this link out:
http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/mulslid.html

 

[u0362565]

No i don't think i can, i know the power at the output of the laser cavity and the wavelength but I'm not sure how i could calculate the amplitude. However if the laser incident on the grating is only split into zero and +-1 orders and that constitutes 100% of the light then there isn't a general rule of thumb for what approximate light intensity percentage the zeroth would contribute relative to the -+1 orders?
Thanks

 

[Khashishi]

I don't know the answer, but I do know that the answer depends on the blaze angle http://en.wikipedia.org/wiki/Blazed_grating

 

[u0362565]

That's interesting I've not come across blazing before, I think I need more specific info about the grating to work this out, the grating transmits multiple wavelengths so perhaps the blaze angle is optimised for one wavelength only and the rest are a compromise.
Thanks

 

[LoopInt]

You can calculate the interference pattern, then you square the amplitude of the wave of the point you want. There are very good videos on youtube that teach how to do that. Search for single slit diffraction and double.
Sorry I cannot help more, I am very very busy right now =(

 

[u0362565]

Ok thanks i'll take a look. Thanks for your help!