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.
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 solve the injury of optical sight to shooters, which is produced by recoil for using artillery or firearms, and the usage problems of shooters’ eye mask, headband and gas mask, the ocular with long exit pupil distance has been designed based on optical sighting system. The optical properties and aberration characteristics of ocular with long exit pupil distance has been analyzed, the structural style with positive-positive-negative three lens groups has been put forward. According to the aberration theory and the isoplanatic image formation principle, the focal power assignment expression has been deduced by adopting analytical method. By using of optical design software ZEMAX, the ocular with long exit pupil distance has been designed, the focal length of system is 20mm, the exit pupil diameter is 4mm, the field angle is 40°, the distance of exit pupil is 41mm, and the relative eye relief is greater than 2. The design results show if this method has been adopted, the transfer functions of each field are all greater than 0.15 when the ocular with long exit pupil distance locates on 45lp/mm, which can meet the use requirements of visual optical instruments.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.