SBAA217 July   2016 OPT8241 , OPT8320 , OPT9221

 

  1.   Lenses for 3D Time-of-Flight (ToF) Image Sensors
    1.     Trademarks
    2. 1 Background
    3. 2 Lens
      1. 2.1 F Number:
      2. 2.2 Transmission Efficiency
    4. 3 Lens Holder
      1. 3.1 Thread
      2. 3.2 Back Focal Length
      3. 3.3 Centering
    5. 4 Summary

2.2 Transmission Efficiency

Transmission efficiency depends largely on the Anti-Reflective Coatings (ARC) used on the lenses. Typical lenses for visible light have ARC which are wide-band in nature. Lenses for ToF cameras need to work for only a narrow range of wavelengths. This makes the ARC more “monochromatic” (narrow band) in nature. As a general rule, it is possible to make ARCs with better transmission efficiencies for a smaller range of wavelengths. So if a lens has 85% transmission efficiency for a visible range of wavelengths, it should be possible to change the coatings on the lens elements to have transmission efficiency better than 85%.