Question

In the phase contrast microscope setup, the lens used for Fourier transform has a diameter of 5 cm and a focal length of 10 cm. The wavelength used is 500 nm. What should be the size and thickness of the circular spot on a glass plate to be used as the filter, if the material used is MgF2 with a refractive index of 1.38?

Answer 1

The size of the circular spot on the glass plate should be 25 nm and the thickness should be 90.58 nm.

Step-by-step explanation:

In a phase contrast microscope, a circular spot on a glass plate is used as a filter to enhance the contrast of the image. The size and thickness of the spot depend on the properties of the material used and the wavelength of light. In this case, the material used is MgF2 with a refractive index of 1.38 and the wavelength of light is 500 nm.

To calculate the size of the spot, we can use the formula:

Size of spot = diameter of lens * wavelength / (2 * focal length)

Substituting the given values, we have:

Size of spot = 5 cm * 500 nm / (2 * 10 cm) = 25 nm

To calculate the thickness of the spot, we can use the formula:

Thickness of spot = wavelength / (4 * refractive index)

Substituting the given values, we have:

Thickness of spot = 500 nm / (4 * 1.38) = 90.58 nm