These mirrors have high reflectance for specific laser wavelength. That is to say that these mirrors are designed to work at a peculiar wavelength individually. And multilayer coatings are stacks intended to achieve the highest possible reflectance at specific laser line wavelengths and at particular angles of incidence.
Our company has good experience in making this optics, and we offer you a large range of laser mirrors. If you have any technical questions, please contact our engineers.