We supports many researchers in the world, and is always challenging to manufacture very unique product. As one example, we introduce the “Super Mirror” manufactured for Quantum Metrology Laboratory, RIKEN in Japan. Quantum Metrology Laboratory uses an ultra-stable optical cavity with the “Super Mirror” to make a narrow-line-width laser in their highly-precise atomic clock “optical lattice clock”. We has cooperated and received an order of manufacturing ultra-high stable optical cavity used in this “new clock”. This optical cavity should be high finesse to accumulate a lot of light in the cavity, so the mirrors with the reflectance as close to “1” (100%) as possible are required. In order to realize such a special mirror, there are severe technical requirements in roughness for surface polishing and defects in the mirror coating. We had achieved the production of this special mirror as “Super Mirror”. We produces the “Super Mirror” with the (following) three special techniques.
Super high quality Optical Coating technology
For Super Mirror, a coating with extremely small light scattering loss and high laser damage threshold is required. For this purpose, we has used the IBS (Ion Beam Sputtering) technology and developed a capability of producing an world top class Ultra Low Loss (10ppm or less) coating.
Low Scattering Polishing technique
The glass substrate to be used for the Super Mirror is required to have ultimate surface smoothness. To detect the very small irregularities is difficult, but it becomes a problem even if there is roughness of 0.1nm or less. For this reason, from its superior glass polishing technique, We have established a mass production capability of low-scattering substrate of Ra 0.2nm. Furthermore, in order to achieve Ra 0.1nm or less that can not be reached in the conventional polishing, We have co-developed a Near-field Light Etching method. *1
Evaluation technology for the Super Mirror
Reflectivity of the Super Mirror is extremely close to “1”, and therefore it is not possible to make an accurate measurement with standard apparatus. We have created a CRD (Cavity Ring-Down) system for evaluation of the super mirror by ourselves. With this system, it is possible to evaluate the effective reflectance *2, spectral line width and the finesse.
LEFT Pictured :
A resonant optical cavity that utilizes the Super Mirror (5N ultra-high
performance mirror with 99.999% reflectivity –> 3 km to 30 cm).
This product is realized with coating, polishing, and advanced optical
contact technology.