Non-reflective Optical Metal Slit

Metal slit is a component widely used in optical instruments and equipment, whether it is in scientific laboratory instruments, such as spectrometers, optical diffraction experimental instruments, wave-particle duality experiment device; in industrial production line machines, such as light-sensitive components, projection surveying and mapping machines, laser equipment; or some detection equipment in daily life, such as gastroscope, infrared thermometer, all of them have the application of optical metal slits. Metal slits usually need to have good non-reflective and light shielding performance, so black plating (blackening) is usually done on the surface to form a black film on the surface of the metal slit, which can effectively reduce light reflection and increase light transmittance. Commonly used treatment processes are: Physical Vapor Deposition (PVD), Nano Painting, Chromium Oxide (CrO3) Plating.

Physical Vapor Deposition short for PVD, which is a technology that evaporates metal materials in a vacuum environment and then deposits them on the surface of optical metal slit. This treatment method can form a uniform and dense metal film, further improving the light shielding performance of optical metal slit. PVD treatment can not only increase the wear resistance and corrosion resistance of optical metal slit, but also significantly reduce the reflection on the surface of optical metal slit.

Nano painting treatment is a process of uniformly spraying a special optical coating on the surface of the metal optical slit. This special coating has good absorption ability, can absorb excess light, and effectively improve the light shielding performance of optical metal slit. Nano painting treatment can not only provide the non-reflective characteristics required by the metal slit optics, but also improve the durability and reliability of the optic metal slits.

Chromium oxide (CrO3) plating is a surface treatment technology that using the easy passivation characteristics of metal chromium to form a black and extremely thin passivation film on the surface of optical metal slit by electroplating technology. The chrome plating layer has extremely high hardness, and its range can vary from 400 to 1200HV. The chrome-plated layer also has super good performance on heat resistance, gloss and hardness will not change under 500 °C heating temperature. Chromium’s friction coefficient is the lowest of all metals, so chrome plating has good wear resistance. chrome plating layer has good chemical stability, would not react in alkali, sulfide, nitric acid and most organic acids, and would not change color, it can maintain non-reflective for long time use.

To sum up, blackened (black plating) is needed for optical metal slit to meet their non-reflective and good light shielding performance, making optical metal slits widely used in the field of optical industry.