Analysis of Key Points of Coating on Complex Spectroscopy Spectroscope

Complex spectrum lenses mainly include filters, beam splitters and beam combiners, etc. The efficiency problems mainly come from the following two aspects:
 

1. Depolarization treatment under 45° incident conditions

For any optical film (single-layer film or multi-layer film), the effective refractive index of the material determines its spectral characteristics:
                                                     ηs=n*cosθ      ηp=n/cosθ

The above ηs and ηp are the equivalent refractive indexes in the two different polarization states of S and P, θ is the incident angle of light, and n is the refractive index of the film material. It can be seen from the above formula that the effective refractive index of the two polarization states of s and p are equal only in the case of normal incidence. Under the condition of angled incidence, the effective refractive index of the two polarization states of s and p are different. This is the theoretical source of the polarization effect of the film in the case of angled incidence. This polarization effect is also the root of the difficulty of the project's indicators. In order to eliminate the polarization effect, a large number of film layers are needed to match the basic film system. The film thickness of these matching layers is irregular and is very sensitive to the influence of the polarization effect. Therefore, the film thickness error needs to be controlled relatively accurately.

2. The steepness of the transition from the reflective zone to the transmissive zone

The steepness mainly brings the following three problems:   A. The greater the steepness, the more the number of layers, the higher the process stability requirements, and the smaller the system error requirements   B. The greater the steepness, the higher the wavelength positioning accuracy requirements, and the greater the possibility of scrap and rework during manufacturing, and the number of experiments will increase.  C. The greater the steepness, the higher the requirements for uniformity.

The thermal deformation of strong light optical components mainly comes from the absorption of the components, and the absorption source mainly comes from the following three aspects:

 1. The lens element substrate absorbs. To circumvent this, low-absorption Corning quartz or Heraeus quartz can be used as the substrate.
2. Film absorption. In order to reduce the absorption of the film, the electron gun evaporation-high-energy ion beam auxiliary process with extremely low absorption can be used, and the high-purity coating material can be used for plating.
3. Environmental pollution during service. The pollution mainly comes from the poor cleaning of the components during service, and the phenomenon of light-induced absorption caused by the adhesion of impurities and the action of the laser under the action of the laser.
 

The above are some of the main points of the complex spectrum spectroscope coating. If you want to know more, please contact us. United Optical Technology is a spot supplier of standard optical components in China, committed to providing users with various optical components, as well as providing customized services for optical products. Any need for your optical components, we will serve you wholeheartedly and look forward to your contact.