Long-pass/Short-pass Mirror Coating
Dichroic mirrors to combine or separate two beams with different wavelengths.
Coated Laser Optics
Dichroic mirrors are used to combine beams or to split two beams that have different wavelengths. With a long-pass mirror, the long wavelengths are transmitted and the short ones reflected. Short-pass mirrors allow the short wavelengths to pass and reflect the long ones.
These mirrors are available with high power coatings from 192 nm to 5 µm and for cw/fs lasers from 450 nm to 2 µm.
The following "golden rules" can help you find the best combination for your application:
- Bandwidth The bandwidth for the reflected part of the beam is limited. For the best possible beam separation or combination, it is important to allow a wavelength range to be transmitted and individual wavelengths to be reflected. Examples: HR1064HT400-700;HR355HT532+1064
- Polarization The absolute degree of reflection is higher for s-polarized light than it is for p-polarized light. For transmission the relationship is the exact opposite. Therefore, keep the polarizations in your assembly in mind.
- Reflection better than transmission The reflection of a beam is more efficient. If you require greater efficiency at a certain wavelength for your application, consider this when selecting a mirror.
- Beam combination of SHG, THG, ... A reflection peak is generated at the corresponding l/2, l/3,... parts of the reflected wavelength. A long-pass coating should be the preferred choice for this combination. Example: Instead of an HR1064+532HT355 coating, an HR355HT532+1064 coating would be preferred.
Optics Production