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4 / 192018-08-16 | Document No.: AN097
Figure 2: Two options to arrange an 8° tilt of the SFH 4780S illumination module
The hardware / optical system
As empiric data suggests there are various suitable wavelengths for an iris scan
system, depending on eye color. In general, two wavelengths look suitable,
depending on the color of the human iris. For blue and green eyes infrared is a
good illumination wavelength, however a visible wavelength might be superior to
unveil the richness of iris details. For dark iris colors (the majority of eyes globally)
visible wavelengths are not suitable at all (see Figure 3). Here an infrared
wavelength is required to unveil the details of the iris. [1] [3]
Figure 3: Suitable wavelengths for iris scanning. 810 nm presents the best solution for
all eye colors. Additionally the specular reflection of the corneal is low at 810 nm
Cover glass
~8°
~8°
Light bending
structure
(i.e. prism type)
Option 2Option 1Standard
~8°
typ. 8° wedge
to skip pcb
SFH 4780S
SFH 4780S
Dark / brown eyes:
- infrared is best
- visible is not suitable
(poor extraction of
iris details)
Blue / green eyes:
- infrared is good
- visible is best
Best solution
for all eye colours:
OSRAM Opto Semiconductors
SFH 4780S
810 nm emitter