1. Diffraction by N-slits

2. Optical disturbance due to N slits

3. Irradiance due to N-slits I 0 = I rradiance by single slit at  =0

4. For principal maxima or

5. For minima Between consecutive principal maxima, there will be N-1 minima

6. Subsidiary maxima (N-2) subsidiary maxima between consecutive principle maxima

7. For large N, irradiance of first subsidiary maxima

8. Diffraction from multiple slits Slit Diffraction Pattern

9. Normal incidence Transmission grating

10. Oblique incidence a

11. For two wavelengths

12. Grating in spectroscopy Identification of element

13. Dispersive power of grating Width of principal maxima

14. Barely resolved ItIt  s  w

15. Chromatic resolving power of a grating

16. Chromatic resolving power of a prism

18. Reflection grating

19. Diffraction grating

20. The nominal track separation on a CD is 1.6 micrometers, corresponding to about 625 tracks per millimeter. This is in the range of ordinary laboratory diffraction gratings. For red light of wavelength 600 nm, this would give a first order diffraction maximum at about 22°.

21. 15  15  0 nm 450 nm Atomic Force Microscope Image of CD

22. Phase grating Delta function Bessel function

23. Bragg’s law X-ray diffraction from crystals: 2d Sin θ = n λ

25. Electron diffraction patterns of a real 3D quasicrystal. The periodic structure of a crystalline solid acts as a diffraction grating, scattering the electrons in a predictable manner. Working back from the observed diffraction pattern, it may be possible to deduce the structure of the crystal producing the diffraction pattern.

26. 1. Optics Author: Eugene Hecht Class no. 535 HEC/O Central library IIT KGP