Question

Distinguish between frenel and Fraunhoffer diffraction .

Answer 1

Type of diffraction : In this category , the sources and the screen are situated near the obstacle producing diffraction . The beam approaching or going away from the obstacle is not modified by mean of a lens or mirror . The wavefronts in this case, are spherical or cylindrical wavefronts
Fraunhoffer diffraction : In this case , both source and screen are at effective distance from the diffracting device and pattern is the image of source modified by diffraction effects