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

IMAGING TOF RANGE CAMERAS 173
Boundary conditions Calculation
Optical power of 160 LEDs 900mW Beam divergence at the target 7 m
Beam divergence 50° Beam area at the target 38 m 2
Target Projected pixel size on the target 180 mm x
40 mm
Distance 7.5 m Projected size of photogates in the
target
Reflectivity of target
36 mm x
40 mm
0.7 Power on projected photogate area 34 µW
Objective (CS-mount) Reflected power of projected pixel
area
24 µW
Focal length 2.6 mm Effective diameter of objective 2.6 mm
F/# 1.0 Power on pixel in fW 260
Transmission of lens: 0.7 Energy in pixel 6.5E-15 J
Transmission of filter:
0.5 Energy of 1 photon 3.16E-19 J
Sensor Number of photons per pixel 20,600
Pixel size
14.5 µm x
12.5 µm
Number of electrons per pixel 13,400
Operating conditions Sensitivity of output stage 3.6 µV/electr.
Integration time 25 ms Output voltage 48 mV
Wavelength 630 nm
Quantum efficiency 0.65 Resulting distance accuracy < 9 cm
Conversion capacitance 40 fF
Amplification of source follower 0.9
Modulation frequency 20 MHz
Table 6.2 Optical power budget for 160-LED modulated light source.
6.3.3 3D range measurement
Range measurements of 3D scenes are illustrated in Figure 6.19 a to c.
Figure 6.19 a shows photographs of the scene taken with a high-resolution b/w
camera, in order to give the reader a more detailed impression of the scene. In
Figure 6.19 b we show the measured 3D data as a graphical representation, coded
in both color and in the z-axis direction. In Figure 6.19 c we superimpose the 2Db/w
data of the observed scene, also acquired with our 3D TOF camera, on the 3Dgrid,
which results in a more physical impression of the scene.