Laser Beam Magic: Calculating Circular Aperture Diameter

How can we calculate the diameter of a circular aperture using a helium-neon laser beam?

When light from a helium-neon laser (lambda=633 nm) passes through a circular aperture and is observed on a screen (4.0 m) behind the aperture, what is the diameter of the circular aperture?

Calculating the Diameter of Circular Aperture

In this laser application, the diameter of the circular aperture can be determined by using the formula for angular spreading. The diameter of the aperture would be equivalent to the diameter of the laser beam, which is 1.00 mm.

When dealing with the passage of light through a circular aperture, diffraction plays a significant role in determining the behavior of the light waves. In the scenario described with a helium-neon laser beam passing through a circular aperture, the wavelength of the laser beam (633 nm) and the distance to the screen (4.0 m) are crucial factors in calculating the diameter of the aperture.

The formula used to calculate the diameter of the circular aperture in this case involves the concept of angular spreading. By rearranging the formula Δθ = 1.22 λ​ /D to solve for the diameter of the aperture, we find that the diameter is equal to the diameter of the laser beam, which is approximately 1.00 mm.

This calculation provides insight into the relationship between the wavelength of the laser beam, the angular spreading of the light waves, and the diameter of the circular aperture. Understanding these factors helps in optimizing the performance of laser applications and ensuring precise manipulation of light beams.