Optical Beamsplitters
Optical beamsplitters divide one beam into a reflected and a transmitted beam at a set ratio. We supply plate beamsplitters, polarizing and non-polarizing, and cube beamsplitters, with dielectric coatings at 30/70, 50/50 and 70/30 and Inconel metallic coatings, on soda lime, Borofloat® or fused silica from 0.5 to 3 mm thick, with an AR coating on the second side as standard.
Capabilities
Types
Plate and cube · Polarizing and non-polarizing
Split ratios
30/70, 50/50, 70/30 · Custom ratios
Coatings
Dielectric, Inconel · Visible to IR
Substrates
Soda lime, Borofloat®, fused silica · 0.5–3.0 mm thick
Size
¼ in square to 24 in · Larger on request
Back side
AR coated as standard · Polished flat and parallel
Gallery
Get a beamsplitter quote
Tell us the split ratio, angle of incidence, wavelength range, polarization of your source and the size, and we will confirm the coating and substrate.
Beamsplitter Types Compared
The type decides how the beam is split, how much light is lost and whether the transmitted beam shifts.
| Type | How it splits | Angle | Best for |
|---|---|---|---|
| Plate, dielectric | 30/70, 50/50 or 70/30 by intensity, with little absorption | 45° | Imaging and illumination paths, large apertures up to 24 in |
| Plate, Inconel | Neutral split across visible and near-IR, less sensitive to polarization | 45° | Broadband light and mixed or unknown polarization |
| Plate polarizer | Transmits p-polarized light, reflects s-polarized light | 55° | Separating polarization in laser paths |
| Cube, polarizing | Reflects s at 90°, transmits p, no beam shift | 45° | Compact optics and laser systems |
| Cube, non-polarizing | Splits by intensity, no beam shift or second-surface ghost | 45° | Compact imaging and measurement optics |
Coatings, Substrates and Sizes
Split ratio
Standard dielectric coatings split light 30/70, 50/50 or 70/30, and custom ratios are designed to order. Ratios are quoted for unpolarized light at 45°, so state which number is transmission, the angle you will use and the polarization of your source.
Dielectric or Inconel coating
Dielectric coatings lose very little light and are designed for a set wavelength band and angle. Inconel is a metallic coating that keeps the split neutral across a broad band and changes little with polarization or angle, but absorbs part of the light. Choose dielectric when light efficiency matters, Inconel when the spectrum or polarization varies.
Substrate and thickness
Soda lime suits general visible use, Borofloat® adds heat and thermal-shock resistance, and fused silica is used for UV and laser paths. Plates from 0.5 to 3.0 mm are precision polished for flatness and parallelism.
Size and larger mirrors
Plates run from ¼ in square to 24 in. For teleprompters and display mirrors above that size, see our teleprompter glass. To split light by wavelength rather than intensity, use a dichroic hot or cold mirror.
Ghost Images, Beam Shift and Polarization
Every uncoated glass surface reflects about 4% of the light, so the back of a plate beamsplitter adds a faint second image offset by the plate thickness. That is why our stock plates carry an AR coating on the second side; for display and camera work it can bring the back-surface reflection below 0.5%.
A plate at 45° also shifts the transmitted beam sideways by about a third of its thickness: roughly 0.3 mm for a 1 mm plate and 1 mm for a 3 mm plate. In a converging beam the plate adds astigmatism as well. Use the thinnest plate that stays flat at your size, or a cube, which has no shift.
At 45°, a dielectric coating reflects s-polarized light more strongly than p-polarized light. Lasers and LCD screens emit polarized light, so a 50/50 plate rated for unpolarized light can split them unevenly. Tell us the source polarization and we will design the ratio for it.