Diffraction Grating Angles

1. Jan 1, 2012

phantom113

I'm choosing an angle for a diffraction grating such that a particular wavelength λ is retroreflected (reflected back along incident path). The book that I'm looking through treats the blazed diffraction grating as a set of N slits. This results in the equation

I(θ)=$\frac{I(0)}{N^{2}}(sinc(β)^{2})(\frac{sin(Nα)}{sin(α)})^{2}$

where β=(kb/2)sin(θ) and α=(ka/2)sin(θ) with b=length of slit and a=distance between center of two adjacent slits

k is the wavenumber(I think).

What I'm looking for is a kick in the right direction. I'm not sure how this equation helps me. I think there is something fundamental that I'm not understanding. Obviously I want the intensity to be maximized along retroreflected path. Any help would be great. Thank you.

2. Jan 2, 2012

phantom113

Does anyone know how to determine the angle at which to place a diffraction grating such that a particular wavelength of light is reflected back along the path of incidence? Do I need to rephrase the question? Any help is much appreciated.