Question

Diffraction spreading for a flashlight is insignificant compared with other limitations in its optics, such as spherical aberrations in its mirror. To show this, calculate the minimum angular spreading in rad of a flashlight beam that is originally 5.90 cm in diameter with an average wavelength of 610 nm.

Answer 1

The answer is "
`1.2566 * 10^(-5)\,rad`".

Step-by-step explanation:

As per the Rayleigh Criterion the minimum angular spreading, for a circular aperture:

`\theta_{\mathrm{min}}\approx \sin\theta=1.22\,(\lambda)/(d)`

`\theta_{\mathrm{min}}=\mathrm{1.22\,(\left( 610\,nm \right))/(\left( 5.90\,cm \right))=1.22\,(\left( 610*10^(-9)\,m \right))/(\left( 5.90*10^(-2)\,m \right))}`

`=1.22* 103.389 * 10^(-7)\\\\=1.22* 1.03 * 10^(-5)\\\\=\mathrm{1.2566 * 10^(-5)\,rad}`