Chapter 10, Problem 10.4QAP

Interpretation Introduction

(a)

Interpretation:

An echelle grating has a focal length of 0.85 m, diffraction angle of 61°16’ and groove density of 120 groves/mm. Reciprocal linear dispersion for diffraction order 30 of an echelle grating needs to be determined.

Concept introduction:

Theoretical reciprocal linear dispersion can be calculated by the following formula-

$D^{-1}=\frac{d\cos \beta }{nf}$

Here,

D^-1= reciprocal linear dispersion

d= groove width of echelle grating

n= no. of order

f= focal length

β= angle of diffraction

Interpretation Introduction

(b)

Interpretation:

Reciprocal linear dispersion for diffraction order 90 for same echelle grating is to be determined.

Concept introduction:

Theoretical reciprocal linear dispersion can be calculated by the following formula-

$D^{-1}=\frac{d\cos \beta }{nf}$

Here,

D^-1= reciprocal linear dispersion

d= groove width of echelle grating

n= no. of order

f= focal length

β= angle of diffraction