At angled incidence, thicker plates create larger beam shifts.

At a fixed angle and refractive indices, lateral displacement increases directly with plate thickness. The exiting beam remains parallel to the incoming beam.

01

Thickness scales the shift

At fixed angle and refractive indices, doubling plate thickness doubles the perpendicular displacement and the offset at the rear face.

02

The output stays parallel

The second parallel face restores the incident direction, but it cannot restore the original beam line.

03

Use the correct index

Use refractive index at the operating wavelength. Anisotropic crystals require the relevant propagation and polarization model.

Live section view

Follow the beam path

Parallel exit · automatically scaled view
Beam path through a parallel wafer An incident ray refracts inside a parallel wafer and exits parallel to the incident direction with a lateral displacement from the reference path without a wafer.
Incident / exiting beam Refracted path Reference without wafer Perpendicular shift
Perpendicular shift |d|0.000 mm
Internal angle θₜ0.00°
Offset at rear face |Δy|0.000 mm
Path inside wafer ℓ0.000 mm

Calculation trail

From Snell’s law to displacement

Angles are measured from the surface normal.

1 · Refraction

θₜ = asin[(n₁ / n₂) sin θᵢ]

N/A

2 · Parallel plate shift

d = t sin(θᵢ − θₜ) / cos θₜ

N/A

Thickness sensitivity at the current angle and indicesBecause d is linear in t, every additional millimetre adds the same displacement.
0.000 mm/mm