Engineering Physics

14.13 Resolving power of a plane transmission grating

The capacity of an optical instrument to show separate images of very closely placed two objects is called resolving power. The resolving power of a diffraction grating is defined as its ability to form separate diffraction maxima of two closely separated wave lengths.

The expression for resolving power of a grating can be obtained with the aid of Fig. 14.20.

 

Figure 14.20 Calculation of resolving power of a plane transmission granting

In Fig. 14.20, xy represents a plane transmission grating having (e + b) as grating element and N lines per unit width of grating. A light beam having two ...