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

More documents

Recommendations

Info

DEMODULATION PIXELS IN CMOS/CCD 145 5.2.9 Summary The demodulation contrast depends on several parameters: amplitude of gate voltages, demodulation frequency, received optical power density and wavelength of modulated light. Since the CCD shutter mechanism used never has 100% efficiency, even under DC conditions, the demodulation contrast is never better than about 60%. The contrast decreases with higher modulation frequencies, since the photoelectrons do not have enough time to reach the storage site (dump site respectively). The gate voltages PGL and PGR should be chosen to be as high as possible. This is in order to generate high electrical fields in the semiconductor. Even for a voltage difference of 10 V between two adjacent photogates, the saturation velocity of electrons is not yet reached. Therefore, the experimentally measured optimum gate voltages of about 8 V are reasonable: an increase in electrical field still causes an increased drift velocity and hence faster response of charge carriers to the electrical field. For modulation voltages higher than 8 V the maximum signal that can be handled decreases, since the charge handling capability of the pixel is essentially influenced by the potential difference between the modulation gate PGL and the integration gate IG (10.7 V). Furthermore, the demodulation contrast decreases with increasing wavelength. This is because the light penetrates deeper into the semiconductor before photoelectrons are generated. These photoelectrons then need more time to reach the depletion region, where they are separated to the dump- or integration site, depending on their arrival. Also photoelectrons generated far from the surface diffuse in random directions, so that they are equally likely to travel directly to the integration or dump site, independently of the actual biasing conditions of the modulated photogates PGL and PGR. For the BCCD realization of the 1-tap demodulation pixel we have measured a contrast of 40% using 20 MHz (more or less) sinusoidally modulated light of 630 nm wavelength. The SCCD performance is only slightly worse, so that the availability of a buried channel process option is not necessarily needed. For lower modulation frequencies and blue light the contrast is better than 60%, quite close to the prediction of the simple model introduced in Figure 5.14. The contrast decrease towards higher modulation frequencies can at least partly be attributed to the more
146 CHAPTER 5 sinusoidal rather than square shaped modulation signal. This also explains the less significant contrast decrease for the faster blue LED at high modulation frequencies (c.f. Figure 5.21 and Figure 5.22). With our measurements we could prove the validity of the theoretical range accuracy predictions presented in Chapter 4. The actual surprise of the measurements is that demodulation still works excellently if single electrons appear only every 10 th (3 cm range resolution) or even 50 th (13 cm range resolution) modulation cycle (50 ns), assuming an integration time of 50 ms. This astonishingly low optical generation rate of photoelectrons corresponds to a photocurrent of only 320 fA (1 electron in 10⋅50 ns) or even only 64 fA, respectively (1 electron in 50⋅50 ns).
Page 1 and 2:
3D Time-of-flight distance measurem
Page 3 and 4:
To my parents
Page 5 and 6:
Meinen Eltern
Page 7 and 8:
II 4. Power budget and resolution l
Page 10 and 11:
Abstract Since we are living in a t
Page 12:
centimeter accuracy. With the singl
Page 15 and 16:
X Eine elegantere Methode zur Entfe
Page 18 and 19:
INTRODUCTION 1 1. Introduction One
Page 20 and 21:
INTRODUCTION 3 light source observe
Page 22 and 23:
INTRODUCTION 5 Propagation time, ho
Page 24 and 25:
INTRODUCTION 7 Chapter 3 gives a sh
Page 26 and 27:
OPTICAL TOF RANGE MEASUREMENT 9 2.
Page 28 and 29:
Page 30 and 31:
OPTICAL TOF RANGE MEASUREMENT 13 pr
Page 32 and 33:
OPTICAL TOF RANGE MEASUREMENT 15 hi
Page 34 and 35:
OPTICAL TOF RANGE MEASUREMENT 17 Pu
Page 36 and 37:
OPTICAL TOF RANGE MEASUREMENT 19 Ad
Page 38 and 39:
OPTICAL TOF RANGE MEASUREMENT 21 pr
Page 40 and 41:
OPTICAL TOF RANGE MEASUREMENT 23 wh
Page 42 and 43:
OPTICAL TOF RANGE MEASUREMENT 25 δ
Page 44 and 45:
OPTICAL TOF RANGE MEASUREMENT 27 c(
Page 46 and 47:
OPTICAL TOF RANGE MEASUREMENT 29 A
Page 48 and 49:
OPTICAL TOF RANGE MEASUREMENT 31 ph
Page 50 and 51:
OPTICAL TOF RANGE MEASUREMENT 33 Ts
Page 52 and 53:
OPTICAL TOF RANGE MEASUREMENT 35 f1
Page 54 and 55:
OPTICAL TOF RANGE MEASUREMENT 37 an
Page 56 and 57:
OPTICAL TOF RANGE MEASUREMENT 39 in
Page 58 and 59:
OPTICAL TOF RANGE MEASUREMENT 41 Ss
Page 60 and 61:
OPTICAL TOF RANGE MEASUREMENT 43 Fr
Page 62 and 63:
OPTICAL TOF RANGE MEASUREMENT 45 1
Page 64:
Page 67 and 68:
50 CHAPTER 3 the smearing effect, r
Page 69 and 70:
52 CHAPTER 3 3.1 Silicon properties
Page 71 and 72:
54 CHAPTER 3 (a) Figure 3.3 Optical
Page 73 and 74:
56 CHAPTER 3 Quantum efficiency in
Page 75 and 76:
58 CHAPTER 3 The different operatio
Page 77 and 78:
60 CHAPTER 3 (a) (b) Depletion widt
Page 79 and 80:
62 CHAPTER 3 Very special processes
Page 81 and 82:
64 CHAPTER 3 1 kT Dn = ⋅ vth ⋅
Page 83 and 84:
66 CHAPTER 3 The proportionality fa
Page 85 and 86:
68 CHAPTER 3 difference of only 1 V
Page 87 and 88:
70 CHAPTER 3 Flicker noise is cause
Page 89 and 90:
72 CHAPTER 3 A s = sf ⋅ q C ⎡ V
Page 91 and 92:
74 CHAPTER 3 amount of the charge p
Page 93 and 94:
76 CHAPTER 3 substrate (Equation 3.
Page 95 and 96:
78 CHAPTER 3 charge carriers the CT
Page 97 and 98:
80 CHAPTER 3 without causing short
Page 99 and 100:
82 CHAPTER 3 Over an address decode
Page 101 and 102:
84 CHAPTER 3 Orbit’s 2.0µm CMOS/
Page 103 and 104:
86 CHAPTER 4 Figure 4.1 P lens Lamb
Page 105 and 106:
88 CHAPTER 4 Required optical power
Page 107 and 108:
90 CHAPTER 4 4.2 Noise limitation o
Page 109 and 110:
92 CHAPTER 4 number of pseudo-backg
Page 111 and 112: 94 CHAPTER 4 Cmod = 1 QE(λ) = 0.65
Page 113 and 114: 96 CHAPTER 4 Range accuracy (std) i
Page 116 and 117: DEMODULATION PIXELS IN CMOS/CCD 99
Page 168 and 169: IMAGING TOF RANGE CAMERAS 151 6. Im
Page 170 and 171: IMAGING TOF RANGE CAMERAS 153 contr
Page 172 and 173: IMAGING TOF RANGE CAMERAS 155 6.1.2
Page 174 and 175: IMAGING TOF RANGE CAMERAS 157 gate
Page 176 and 177: IMAGING TOF RANGE CAMERAS 159 6.2 2
Page 178 and 179: IMAGING TOF RANGE CAMERAS 161 n+ di
Page 180 and 181: IMAGING TOF RANGE CAMERAS 163 pixel
Page 182 and 183: IMAGING TOF RANGE CAMERAS 165 Power
Page 184 and 185: IMAGING TOF RANGE CAMERAS 167 Delay
Page 186 and 187: IMAGING TOF RANGE CAMERAS 169 6.3 3
Page 188 and 189: IMAGING TOF RANGE CAMERAS 171 Gate
Page 190 and 191: IMAGING TOF RANGE CAMERAS 173 Bound
Page 192 and 193: IMAGING TOF RANGE CAMERAS 175 Figur
Page 194 and 195: IMAGING TOF RANGE CAMERAS 177 Final
Page 196 and 197: IMAGING TOF RANGE CAMERAS 179 #5 #6
Page 198 and 199: SUMMARY AND PERSPECTIVE 181 7. Summ
Page 200 and 201: SUMMARY AND PERSPECTIVE 183 into th
Page 202: SUMMARY AND PERSPECTIVE 185 or phas
Page 205 and 206: 188 CHAPTER 8 8.2 Typical parameter
Page 207 and 208: 190 CHAPTER 8 Spectral luminous int
Page 209 and 210: 192 CHAPTER 8 MCD03S: Conditions SC
Page 211 and 212: 194 CHAPTER 8 MCD06S: Measurement c
Page 213 and 214:
196 [BRK] Brockhaus, “Naturwissen
Page 215 and 216:
198 [KAI] I. Kaisto, et al., “Opt
Page 217 and 218:
200 [SP1] T. Spirig et al., “The
Page 220 and 221:
ACKNOWLEDGMENTS 203 Acknowledgments
Page 222:
206 Publication list 1. R. Lange, P
show all

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

Create successful ePaper yourself

Delete template?

Save as template?