Laser optics have complex coatings on both sides
Coated laser optics are used to optimise the characteristics of the laser beam, however, losses occur at each surface due to reflection. To keep these losses to a minimum the number of optics in a system should be kept as low as possible. LASER COMPONENTS offers laser optics with complex coatings on both sides.
For a long time this has been almost impossible to achieve, the temperatures required to apply the second complex coating would heat the first coating and cause cracking. This effect is only worsened by the complexity of the second coating, the more complex the coating the more layers are required. This directly translates to length of exposure to extreme temperatures.
Our complex coating designs are manufactured to customer specifications; there are a large number of combinations available. Laser optics with complex coatings on both sides are commonly used in resonators and polarisers. For resonator applications, the dichroic coating is usually on the front (a DPSS example: the coating would reflect 1064nm light but allow through the pump wavelength) the rear coating can then be highly or partially reflective for either the same or another wavelength.
It is also possible to combine a polarisation coating on one surface and a mirror coating on the other. An example could be a thin film polariser coating for use at 45° at 1064nm, the rear side of the optic could be coated to allow for coupling of another wavelength.
Polarisation coatings are required on both sides of an optic in applications when the polarisation effect has to be increased, as well as when high extinction ratios are necessary that cannot be achieved otherwise.