Research of Low Angle Effect Bandpass Filter for Iris Recognition

Research of Low Angle Effect Bandpass Filter for Iris Recognition

Citation

岳鹏飞 [Yue Pengfei]. 用于虹膜识别的低角度效应带通滤光片的研制 [Research of Low Angle Effect Bandpass Filter for Iris Recognition]. 长春理工大学 [Changchun University of Science and Technology], 2020. 硕士学位(毕业)论文 [Master's Thesis (Graduation Thesis)].

Keywords

  • 虹膜识别 / Iris recognition
  • 低角度效应 / Low angle effect
  • 带通滤光片 / Bandpass filter
  • 光学薄膜 / Optical film / Thin film
  • a-Si:H
  • Si3N4
  • SiO2
  • 折射率 / Refractive index
  • 等离子体辅助中频孪生靶反应磁控溅射 / Plasma-assisted intermediate-frequency twin-target reactive magnetron sputtering
  • 950 nm
  • 近红外光 / Near-infrared light
  • 双面拆分原理 / Double-sided split principle
  • 通带透射率 / Passband transmittance
  • 偏移量 / Offset / Spectral shift
  • 色散模型 / Dispersion model
  • Macleod
  • 法布里-珀珞 / Fabry-Pérot
  • 长波通 / Long-wave pass
  • 膜系设计 / Film system design
  • 光谱测试 / Spectrometry / Spectral test
  • 保护层 / Protective layer
  • 角度效应 / Angle effect
  • 生物识别系统 / Biometric recognition system
  • 图像识别技术 / Image recognition technology

Brief

This article details the research and development of a low-angle effect bandpass filter centered at 950 nm for iris recognition systems, focusing on material selection (a-Si:H, Si3N4, SiO2), fabrication using plasma-assisted magnetron sputtering, and achieving high transmittance with minimal spectral shift at large incident angles.

Summary

This article details the development of a bandpass filter for iris recognition systems that minimizes performance changes at different viewing angles (low angle effect). The researchers used a-Si:H, Si3N4, and SiO2 thin films deposited via a special sputtering technique to create a filter centered at 950 nm. This filter achieved high light transmission in the desired range with only a small shift in performance even when light entered at large angles (up to 38°), making it suitable for reliable iris scanning.

Origin:

Back to blog