Young’s Double Slit

The experiment named for Thomas Young’s classic proof of the wave theory of light in 1803. While Young’s original experiment used sunlight and calculated the average wavelength to be 550nm, today using monochromatic and coherent light one can calculate wavelength with the following formula:

nλ = xd/L


λ is the wavelength of the light
d is the separation of the slits
n is the order of maximum observed ( for first order n=1)
x is the distance between the bands of light and the central maximum
L is the distance from the slits to the screen center point.

Young’s Double Slits are manufactured by the Lenox Laser Corporation’s proprietary technology that gives a very sharp edge to every slit that makes the geometries and areas of each slit equal (within specifications). This guarantees a very high contrast of diffraction patterns and low flux variations through each of the slits providing good metrology.

In application, these slits may be used to demonstrate Young’s Interference Fringes, Michelson’s Stellar Interferometer (for measuring the separation between double stars) or other applications requiring measurement of the separation between point sources. Go to the Young’s Double Slit Page to activate an interactive applet that will show Young interferences resulting from the interaction of a certain number of waves.

For more information call 1-800-49HOLES or 410-592-3106 or email