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

120 CHAPTER 5
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Linearity measurement (I): FS46
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BRIGHT measurement
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Linearity measurement (II): FS46
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DARK measurement
Figure 5.10 Linearity measurements of the output stage for different illumination
intensities and integration times (0-50 ms).
The measurement (Figure 5.10) is performed for two illumination intensities, one
nearly leading to saturation of the output stage for the longest integration time
(BRIGHT measurement) and the other with a factor of 100 lower intensity (DARK
measurement). The measurement conditions chosen are summarized in MCD01 in
the appendix. For the quantization of the analog output, we use the EPPI
(Enhanced Parallel Port Interface, a CSEM product), a 12 bit frame grabber that
can be connected to the parallel port of a PC.
We can already judge by eye that the overall system linearity appears to be good
(Figure 5.10). Only for very low output voltages (DARK measurement) does the
linearity deteriorate. To judge the actual influence of this DARK measurement
nonlinearity, we approximate the measured curve with a polynomial. This can easily
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be done with MATLAB (polynom: 13. 2 ⋅ x − 0.
53 ⋅ x + 0.
02 ⋅ x − 0.
0003 ⋅ x , for
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