Beam Displacement Calculator

This is an online calculator to find the displacement of a collimated beam incident on a tilted plane-parallel plate or window. Just enter the incidence angle, plate thickness, and refractive index to get the displacement value. This calculator also determines the displacement of the secondary reflection resulting from a small portion of the beam reflecting off the glass-air interface of the plate.

Enter the Incidence Angle, Plate Thickness, and Refractive Index to Calculate the Displacement Value

  • θ
  • mm

Result

  • Beam Displacement
    mm
  • Displacement of Secondary Reflection
    mm
Image for Beam Displacement Calculator

Conversion Equation


Where ‘t’ is the thickness of the plate, ‘θ’  is the angle of incidence between beam and plate normal, and ‘n’  is the refractive index of the medium.

Beam Displacement is the displacement of a collimated beam incident on a tilted plane-parallel plate or window. This displacement occurs as a result of the beam travelling from one media to another media with a different refractive index. The change in refractive indices causes the beam to displace from its original path.


Collimated beam of light is a beam whose rays are parallel to each other and so has the least divergence.

Divergence  is a measure of the beam spreading out.

Displacement of secondary reflection results from a small portion of the beam reflecting off the glass-air interface of the plate.