The Positive Meniscus Lenses are a convex-concave lens, but it is thicker at the center than at the edges. They are felt polished and are used universally in the ophthalmic industry where convention dictates that lens power be specified in Diopters.

The Negative Meniscus Lenses are a convex-concave lens, but it is thinner at the center than at the edges. Otherwise description is similar to Plano Concave lenses.

1、What Metallic Coated types can Uni-Optics supply? Uni-Optics mainly offers four coating types, including: 1) UV Enhanced Aluminum : Ravg > 85% from 250nm to 400nm 2) Protected Aluminum: Ravg > 87% from 400nm to 800nm 3) Protected Silver: Ravg > 95% from 400nm to 20um 4) Protected Gold: Ravg > 98% from 650nm to 16um 2、What are the features of Metallic coated mirror? Metallic coated mirror have many key features below: Wide spectral range Not sensitive to the incidence angle and polarization state Low cost Non-durable Relatively low reflectance Low laser damage threshold 3、What UNI Optics can do for you? Common Specifications: Substrate Materials: N-BK7, Fused silica, Pyrex；Float glass Dimensional tolerance: +/-0.1mm Surface quality:  60-40 Parallelism:  3’ Flatness: λ/4 per 25mm@633nm Bevel: Protective One surface: Polished and Metallic coating The other surface: Fine ground Note: Aluminum is the most widely used metal reflection film, from near UV to near IR, have high reflectivity, and with low cost. Silver has higher reflectivity in the visible and near infrared wavelength than the aluminum film, but the silver in the air will be rapid oxidation, color darkening, makes the film performance and firmness declined rapidly. Gold film has a good consistency with high reflectivity in the near, middle and far infrared range, can control the thermal radiation effectively, but it is relatively soft, easy bruising, and should be paid very close attention to clean, and the cost is very high.