There are numerous applications for multispectral filter film, including remote sensing detection, medical treatment, and military camouflage recognition. The process of preparing it is complex, which has resulted in a high price tag and low yield. We use electron beam evaporation to create five-spectral-band filter films between 380 and 900 nm using Ta2O5 and SiO2. Multispectral filter films with different bandwidths are designed using multiple methods derived from thin-film theory. Using the characteristics of each channel spectrum, three methods of monitoring film thickness were combined to prepare each channel: crystal oscillator monitoring, back-reflection monitoring, and optical transmittance monitoring. Using mechanical masks to prepare each channel individually, the transmittance over the passband is greater than 95%, and the spectral rectangle meets the requirements of applications.
With the wide application of optical thin films, the requirements for the spectral transmission range and refractive index of thin film materials are getting higher and higher. In this paper, a new type of thin film material sintered from SiO2 and Al2O3 is studied. The single-layer film was evaporated by electron beam evaporation, and its refractive index uniformity was measured by ellipsometer and its spectral transmission range was measured by spectrophotometer and Fourier spectrometer. Finally, a multi-layer high-reflection film is prepared by using the material, and the film has a high reflectivity and a flat and uniform surface.
Terahertz nondestructive testing technology is a technology widely used in samples evaluation with the merit of on-site and surface-damage free. Terahertz waves have low quantum energy and are transparent to most non-polar substances, thus, terahertz nondestructive testing has gradually become a research hotspot over the years. However when a femtosecond laser in used as a terahertz excitation source, the excess pump light in the system may cause radiation damage to the measured object. In order to eliminate the impact of residual pump light in the system on the measured object, we designed the spectral filter elements of reflect and terahertz band transmission in the wave bands of 0.80 μm and 1.56 μm, by using Nb2O5 and SiO2 as high and low refractive index materials, respectively. Then we prepared the filter membrane system electron beam evaporation through an ion beam assisted deposition. The influence of annealing process on the growth structure of the films was analyzed according to the AFM test results of Nb2O5 monolayer films under different process conditions, and the annealing process parameters were optimized to reduce the influence of surface roughness on the film spectrum. Based on the KIM vibration model (Lorentz extension model), the optical constant dispersion distributions of NB2O5 thin flims prepared under different processing conditions were accurately fitted. The influence of temperature on the refractive index and absorption of Nb2O5 thin films were analyzed. The deposition temperature was optimized to reduce the absorption of the filter in the wave bands of 0.8 μm and 1.560 μm. By using PE Lambda 1050, the reflectivity of the prepared filter in the wave bands of 0.8 μm and 1.560 μm were tested. The prepared filter was scanned by focusing point by point using a built-up transmission terahertz time domain spectral system. The transmittance of the quartz coated sample relative to the reference signal was calculated by analyzing signals in the frequency domain. The average reflectivity of the prepared spectral filter was 99.9% in both the band of 0.9 μm and 1.560 μm. The transmittance of terahertz frequency 2 THz was 68%, which was almost consistent with the theoretical design values, and could meet the requirements for the terahertz nondestructive testing system's application.
In order to obtain high-performance short-mid infrared anti-reflection membrane, Si, SiO, and MgF2 are used to design the system structure, in which MgF2 is located in the outermost layer and expose in the atmosphere. However, due to the porous structure of fluoride thin film, the peaking density of MgF2 film is low, which is prone to the moisture absorbing. The water vapor comes into the film not only caused the transmittance decrease but also lead to the poor adhesion. The excessive power of ion source assisted deposition increases the stress of MgF2 film, resulting in the stress mismatch between MgF2 film and the previous Si layer, caused the MgF2 film cracks. To improve the adhesion of the film, this paper invests a way to matching stress by plating bond layer between MgF2 and Si, and adopts the step annealing process combined with ion beam assisted deposition to improve the film aggregation density and decrease the absorption of water vapor, and further reduce the film stress. The spectral transmittance of prepared films is greater than 96% in1.5~5μm. After 7 days, the spectral transmittance decreased by only 0.6% and remained stable for the next 30 days. The prepared film with high quality can through 10 times adhesive test without fracture.
In recent years, the Ministry of Education of China attaches great importance to the reform of higher education quality. As an important link in the reform of higher education, curriculum development is bound to promote the development of "quality-centered connotative education". Zhejiang University, Changchun University of Science and Technology, Southern Airlines University and other colleges and universities carried out a full range of close cooperation, proposed integrated innovation teaching mode of the course based on network technology. Based on this model, the course of "Applied Optics" has been practiced for two years. The results show that the integrated innovation teaching mode can fully realize the integration amplification effect among multiple colleges and universities and the depth sharing all types of resources. Based on the principle of co-building and sharing, mutual help, comprehensively improve the teaching quality of domestic related courses and promote the comprehensive development of the curriculum to meet the needs of learning society.
BaTiO3 film is deposited on single crystal MgO substrate with pulsed laser deposition, and its crystal structure and surface roughness are characterized by X-ray diffraction instrument and atomic force microscope. BaTiO3 film crystal quality is analyzed under three different oxygen partial pressure and three different annealing temperatures. The result shows that when the oxygen partial pressure is 15Pa, crystal surface (001) and (002) diffraction peak of BaTiO3 thin films have higher intensity. It indicated that the film has a good c-axis orientation. When the annealing temperature is 800°C, the intensity of diffraction peak is the maximum, and peak shape is sharper. BaTiO3 crystal film is obtained with highly preferred orientation, and film density is improved. Thus the film has less surface roughness and good crystalline state.
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