A 1:8 beam splitter directs approximately 1/9 of the incident light into the reflected path and 8/9 into the transmitted path, so to turn on a light effectively, you should align the transmitted beam toward your target.

Understanding the 1:8 Beam Splitter

A 1:8 beam splitter is a non-polarizing optical device that splits incoming light into two beams with a fixed ratio: about 11% of the light is reflected and 89% is transmitted . This means most of the light continues along the transmitted path, which is typically the path you would use to illuminate a light or sensor.

Steps to Turn On a Light

1. Identify the transmitted and reflected paths: For plate or cube beam splitters, the transmitted beam usually continues straight through, while the reflected beam exits at a 90° angle (for cubes) or at a 45° angle (for plates) relative to the incident beam .
2. Align the light source: Position your light source so that it hits the beam splitter at the designed angle of incidence, usually 45° for plate splitters or along the marked input face for cube splitters .
3. Direct the transmitted beam: Since the transmitted beam carries the majority of the light (8 parts out of 9), aim this beam toward the light you want to turn on. Ensure there are no obstructions and that the beam is focused if necessary.
4. Optional reflection use: If you also need a secondary, weaker illumination, the reflected beam can be directed to another target, but it will be much dimmer due to the 1:8 ratio .
5. Check for losses: Be aware that all beam splitters introduce some light loss due to absorption or scattering, so the actual transmitted intensity may be slightly less than 89% .

Additional Considerations

• Type of beam splitter: Cube splitters are more compact and reduce beam displacement, while plate splitters are lighter and easier to integrate in space-constrained setups .
• Polarization effects: Non-polarizing splitters are preferred if you want to maintain the light's polarization state; polarizing splitters will separate light based on polarization, which may reduce intensity in one path .
• Alignment precision: Small misalignments can significantly reduce the light reaching your target, so use adjustable mounts for precise positioning. By following these steps, you can effectively use a 1:8 beam splitter to direct the majority of light toward a target and "turn on" a light in your optical setup.