The way in which the diffraction angle *λ**β* behaves when light composed of different wavelengths is directed at a grating is an important point when considering the separation of light into its components. If the incident angle *α* is regarded as a constant, differentiating both sides of equation (2) with respect to λ gives the following:

Here, d*β*/dλ is called the **"angular dispersion"** and can be used to obtain the change in diffraction angle d*β*corresponding to a change in wavelength dλ. Multiplying both sides of equation (3) by the focal distance ƒ for the optical systems gives the following:

When ƒ·d*β* = dx, inverting both sides of equation (4) gives the following:

Here, *D* is called the **"reciprocal linear dispersion"** and represents the difference in wavelength per unit length on the surface of the exit slit in the optical system. Multiplying *D* by the slit width gives an indication of the wavelength resolution.

- SHIMADZU DIFFRACTION GRATINGS
- 01. Introduction to Diffraction Gratings
- 02. What are Diffraction Gratings
- 03. The Grating Equations
**04. Dispersion**- 05. Grating Resolution
- 06. Free Spectral Range
- 07. Blaze Wavelength
- 08. Diffraction Efficiency & Relationship between Diffraction Efficiency and Polarization
- 09. Anomalies
- 10. Profile of Grating Grooves
- 11. Toroidal Diffraction Gratings
- 12. Replicas
- 13. Coatings
- 14. Transmission Gratings
- 15. Choice of a Grating
- 16. Handling of Gratings