3D Time-of-flight distance measurement with custom - Universität ...

OPTICAL TOF RANGE MEASUREMENT 9
2. Optical TOF range measurement
The basic principles of optical range measurement techniques (1) triangulation, (2)
interferometry and (3) time-of-flight are introduced in this chapter. All these
techniques mostly work with light, i.e. electromagnetic radiation fields in the
wavelength range of 400-1000 nanometers (visible and NIR spectrum). We present
a rough description of the basic working principles. The advantages and
disadvantages of each principle are discussed and some examples are also given.
More detailed and broader overviews over optical ranging principles can be found
in the references [KAP], [BES], [ENG], [EN2], [SC1]. Figure 2.1 shows the family
tree of contactless 3D shape measurement techniques.
Triangulation
Contactless 3D shape measurements
Microwave
λ = 3 - 30 mm
(10 - 100 GHz)
depth detection by
means of geometrical
angle measurement
Light wave
λ = 0.5 - 1 µm
(300 - 600 THz)
Interferometry
depth detection by
means of optical coherent
time-of-flight measurement
Ultrasonic wave
λ = 0.1 - 1 mm
(0.3 - 3 MHz)
Time-of-flight (TOF)
depth detection by
means of optical modulation
time-of-flight measurement
Figure 2.1 Family tree of contactless 3D shape measurement [SC1].
Since TOF measurement is the underlying principle of this work, it is discussed in
more detail. The first part of this chapter is closed by a discussion and a
comparison of the different ranging techniques. It should be mentioned that also
microwave (λ=3–30 mm) and ultrasound (λ=0.1-1 mm) techniques have their
application-specific advantages. However, they are not included in this comparison.
Due to diffraction limitations, both techniques are not suited for range
measurements with high angular resolution, at an acceptable size of the