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

Lens

An example lens specification which works well for a 3D ToF system is shown in Table 1.

Table 1. Lens Specifications

Specification Value
Sensor Format Horizontal 80 pixels
Vertical 60 pixels
Sensor Pixel size Horizontal 30 um
Vertical 30 um
Light Wavelength 850 nm
Effect Focal Length (EFL) 1.62 mm
F.No 1.2
Transmission efficiency >85% @ 850 nm
>80% @ 835 nm to 870 nm
>70% @ 800 nm to 900 nm
Lens Total Length <10.0 mm
View Angle Horizontal (deg) 75°
Vertical (deg) 57.4°
Diagonal (deg) 90°
Resolution (MTF) On Axis > 70% contrast at 17 lp/mm
Full Field > 50% contrast at 17 lp/mm
TV distortion (Trad.) < 10%
Relative Illumination (Ref.) 70%
Chief Ray Angle < 10%
Maximum Image Circle (MIC) 3.6 mm
Back Focal Length 1.0 mm
Barrel Thread Size M12 × 0.5

Detailed information on each of these topics is freely available on the internet. This document deals only with the specifications important to the topic.