Velodyne VLP-32C - F.2.3 Beam Divergence

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Figure F-3 Laser Spots on a Wall

Photo of sensor laser pattern reflecting off of a flat target a short distance away.

F.2.3 Beam Divergence

As a laser pulse propagates outward from the sensor the cross-section of the laser beam describing the path of the pulse

gradually, steadily grows larger. The angular measure of this increase in beam path diameter is called Beam Divergence.

Appendix F • Laser Pulse 119

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default chapter2
- Method2
- Method3
- Table of Contents4
Chapter 1 • about this Manual16
- Manual Scope16
- Prerequisite Knowledge16
- Audience16
- Document Conventions16
- Table 1-1 Document Conventions16
- Figure 2-1 Example 3D Sensing System18
Chapter 2 • VLP-32C Overview 2.1 Overview19
- Product Models19
- Time of Flight19
- Data Interpretation Requirements19
- Table 2-1 3D Sensing System Components19
Chapter 3 • Safety Precautions20
- Warning and Caution Definitions20
- Caution Hazard Alerts20
- Safety Overview20
- Electrical Safety20
- Mechanical Safety20
- Laser Safety20
- Figure 3-1 Class 1 Laser21
Chapter 4 • Unboxing & Verification22
- What's in the Box22
- Variants22
- Verification Procedure22
- Network Setup in Isolation23
- Figure 4-1 Sensor Network Settings23
- Access Sensor's Web Interface24
- Figure 4-2 Interface Box (Power and Data Connections)24
- Figure 4-3 Sample Web Interface Main Configuration Screen25
- Visualize Live Sensor Data with Veloview26
- Veloview Operation27
- Figure 4-4 Veloview Open Sensor Stream27
- Figure 4-5 Veloview Select Sensor Calibration27
- Figure 4-6 Veloview Sensor Stream Display28
Chapter 5 • Installation & Integration29
- Overview29
- Mounting29
- Figure 5-1 Mounting Details29
- Encapsulation, Solar Hats, and Ventilation30
- Connections30
- Interface Box and Cable31
- Operation Without an Interface Box31
- Power31
Chapter 6 • Key Features32
- Calibrated Reflectivity32
- Laser Return Modes32
- Single Return Modes: Strongest, Last32
- Multiple Returns33
- Dual Return Mode33
- Figure 6-1 a Single Return33
- Figure 6-2 Dual Return with Last and Strongest Returns34
- Figure 6-3 Dual Return with Second Strongest Return35
- Figure 6-4 Dual Return with Far Retro-Reflector36
- Phase Locking Multiple Sensors37
- Figure 6-5 Forestry Application Multiple Returns37
- Figure 6-6 Phase Locking Example38
Chapter 7 • Sensor Inputs39
- Power Requirements39
- Interface Box Signals40
- Table 7-1 Interface Box Signals40
- Figure 7-1 Interface Box40
- Ethernet Interface41
- GPS, Pulse Per Second (PPS) and NMEA Sentence41
- GPS Input Signals41
- Electrical Requirements41
- Timing and Polarity Requirements41
- Figure 7-2 Synchronizing PPS with NMEA GPRMC Message41
- Figure 7-3 PPS Signal Closely Followed by NMEA GPRMC Message42
- Figure 7-4 PPS Signal Followed 600 Ms Later by NMEA GPRMC Message42
- Figure 7-5 RS-232 Example Transmission43
- GPS Connection Scenarios44
- Connecting a Garmin 18X LVC GPS Receiver44
- Figure 7-6 Garmin 18X LVC Configuration44
- Figure 7-7 Garmin GPRMC Message45
- Connecting to a Computer's Serial Port46
- Connecting to a Microcomputer's UART46
- Figure 7-8 DB9 Pin-Outs (DTE) and USB-To-Serial Adapter46
- Figure 7-9 Signal Directly from UART (Incorrect Polarity)46
- NMEA Message Formats47
- Pre-NMEA Version 2.3 Message Format47
- Figure 7-10 Inverted Signal from UART (Correct Polarity)47
- NMEA Version 2.3 Message Format48
- Table 7-2 Pre-NMEA Version 2.3 Message Format48
- Table 7-3 Post-NMEA Version 2.3 Message Format48
- Accepting NMEA Messages Via Ethernet49
Chapter 8 • Sensor Operation50
- Firing Sequence50
- Throughput Calculations50
- Data Packet Rate50
- Figure 8-1 Firing Sequence Timing50
- Position Packet Rate51
- Total Packet Rate51
- Laser Measurements Per Second51
- Single Return Mode (Strongest, Last)51
- Dual Return Mode51
- Rotation Speed (RPM)51
- Horizontal Angular (Azimuth) Resolution51
- Rotation Speed Fluctuation and Point Density52
- Table 8-1 Rotation Speed Vs Resolution52
- Figure 8-2 Point Density Example52
Chapter 9 • Sensor Data53
- Sensor Origin and Frame of Reference53
- Calculating X,Y,Z Coordinates from Collected Spherical Data53
- Packet Types and Definitions54
- Definitions54
- Figure 9-1 VLP-32C Sensor Coordinate System54
- Firing Sequence55
- Laser Channel55
- Data Point55
- Azimuth55
- Data Block55
- Time Stamp55
- Factory Bytes56
- Data Packet Structure56
- Table 9-1 Factory Byte Values56
- Figure 9-2 VLP-32 Single Return Mode Data Structure57
- Table 9-2 VLP-32C Data Order in Data Block58
- Figure 9-3 VLP-32 Dual Return Mode Data Structure58
- Position Packet Structure59
- Table 9-3 Position Packet Structure Field Offsets59
- Table 9-4 PPS Status Byte Values61
- Figure 9-4 Wireshark Position Packet Trace61
- Discreet Point Timing Calculation62
- Table 9-5 VLP-32C's Lasers Fire in Pairs62
- Figure 9-5 Firing Sequence Timing62
- Figure 9-6 Example Data Point Timing Calculation64
- Figure 9-7 Single Return Mode Timing Offsets (in Μs)65
- Precision Azimuth Calculation66
- Table 9-6 VLP-32C Azimuth Offsets by Elevation66
- Figure 9-8 Dual Return Mode Timing Offsets (in Μs)66
- Converting PCAP Files to Point Cloud Formats69
Chapter 10 • Sensor Communication70
- Web Interface70
- Configuration Screen71
- Table 10-1 Configuration Screen Functionality and Features71
- Figure 10-1 VLP-32C Configuration Screen71
- MAC Address73
- Correctly Reset MAC Address to Factory MAC Address73
- System Screen74
- Table 10-2 System Screen Functionality and Features74
- Figure 10-2 VLP-32C System Screen74
- Info Screen75
- Table 10-3 Info Screen Functionality and Features75
- Figure 10-3 VLP-32C Info Screen75
- Diagnostics Screen77
- Table 10-4 System Screen Functionality and Features77
- Figure 10-4 VLP-32C Diagnostics Screen77
- Sensor Control with Curl78
- Using Curl with Velodyne Lidar Sensors78
- Curl Command Parameters78
- Command Line Curl Examples79
- Get Diagnostic Data79
- Conversion Formulas80
- Interpret Diagnostic Data80
- Top:hv80
- Top:lm20_Temp81
- Top:pwr_5V81
- Top:pwr_2_5V81
- Top:pwr_3_3V81
- Top:pwr_Raw82
- Top:pwr_Vccint82
- Bot:i_Out82
- Bot:lm20_Temp82
- Bot:pwr_V_In84
- Get Snapshot84
- Get Sensor Status84
- Set Motor RPM84
- Set Field of View85
- Set Return Type (Strongest, Last, Dual)85
- Save Configuration85
- Reset System85
- Network Configuration86
- Set Host (Destination) IP Address86
- Set Data Port86
- Set Telemetry Port86
- Set Network (Sensor) IP Address86
- Set Netmask86
- Set Gateway86
- Set DHCP86
- Curl Example Using Python87
Chapter 11 • Troubleshooting89
- Troubleshooting Process89
- Table 11-1 Common Problems and Resolutions89
- Turned DHCP On, Lost Contact with Sensor90
- Service and Maintenance91
- Fuse Replacement91
- Technical Support92
- Purchased through a Distributor92
- Factory Support92
- Support Desk92
- Return Merchandise Authorization (RMA)92
Appendix A • Sensor Specifications93
Appendix B • Firmware Update94
- Firmware Update Procedure94
- Figure B-1 Velodyne Downloads Page94
- Figure B-2 Compare Firmware Versions95
- Figure B-3 Select New Firmware Image96
- Figure B-4 Upload New Firmware Image97
- Figure B-5 Firmware Update Complete Page98
- Figure B-6 Finalize Firmware Update99
- Special Procedure to Update Firmware100
- Figure B-7 Verify Firmware Versions100
- If an Error Occurs101
Appendix C • Mechanical Diagrams102
- Interface Box Mechanical Drawing103
- Figure C-1 Interface Box Mechanical Drawing 50-6001 Rev a103
- VLP-32C Mechanical Drawing104
- Figure C-2 VLP-32C Mechanical Drawing 86-0130 Rev 1104
Appendix D • Wiring Diagrams105
- Interface Box Wiring Diagram106
- Figure D-1 Interface Box Wiring Diagram 86-0107A106
- Interface Box Schematic107
- Figure D-2 Interface Box Schematic 69-8230A107
Appendix E • Veloview108
- Features108
- Install Veloview109
- Visualize Streaming Sensor Data109
- Figure E-1 Veloview Open Sensor Stream109
- Figure E-2 Veloview Select Sensor Calibration110
- Capture Streaming Sensor Data to PCAP File111
- Figure E-3 Veloview Sensor Stream Display111
- Replay Captured Sensor Data from PCAP File112
- Figure E-4 Veloview Record Button112
- Figure E-5 Veloview Open Capture File113
- Figure E-6 Veloview Play Button113
- Figure E-7 Veloview Spreadsheet Tool114
- Figure E-8 Veloview Data Point Table114
- Figure E-9 Veloview Show Only Selected Elements115
- Figure E-10 Veloview Select All Points115
- Figure E-11 Veloview List Selected Points116
Appendix F • Laser Pulse117
- The Semiconductor Laser Diode117
- Figure F-1 Laser Diode Concept117
- Laser Patterns118
- Laser Spot Pattern118
- Laser Scan Pattern118
- Figure F-2 Laser Spot Shape118
- Beam Divergence119
- Figure F-3 Laser Spots on a Wall119
- Table F-1 VLP-32C Beam Divergence120
Appendix G • Time Synchronization121
- Introduction121
- Background121
- Figure G-1 Web Interface PPS and GPS Qualifier Option Selections121
- PPS Qualifier122
- Require GPS Receiver Valid122
- Require PPS Lock122
- Figure G-2 Top of Hour Counters122
- Delay123
- GPS Qualifier123
- Application123
- Logic Tables123
- Figure G-3 Sub-Second Counter Behavior123
- Figure G-4 Minutes and Seconds Counter Behavior124
Appendix H • Phase Lock125
- Phase Lock125
- Setting the Phase Lock125
- Figure H-1 Direction of Laser Firing125
- Application Scenarios126
- Figure H-2 Configuration Screen - Phase Lock126
- Figure H-3 Right and Left Sensor Phase Offset127
- Figure H-4 Fore and Aft Sensor Phase Offset127
- Field of View128
- Figure H-5 Sensor Data Shadows128
Appendix I • Sensor Care129
- Cleaning the Sensor129
- Required Materials129
- Determine Method of Cleaning the Ring Lens129
- Cleaning Tips130
- Method130
- Cleaning Non-Optical Sensor Surfaces131
Appendix J • Network Configuration132
- Ethernet and Network Setup132
- Defaults132
- Establishing Communication Via Ethernet132
- Network Considerations133
- Throughput Requirements133
- Figure J-1 Sensor Network Settings133
- Single Sensor Transmitting to a Broadcast Address134
- Multiple Sensors in the same Network134
- Multiple Sensors Transmitting to a Broadcast Address134
- Figure J-2 Single Sensor Broadcasting on a Simple Network134
- Multiple Sensors Transmitting to a Specific Address135
- Figure J-3 Multiple Sensors - Improper Network Setup135
- Figure J-4 Multiple Sensors - Proper Network Setup135

Velodyne VLP-32C - F.2.3 Beam Divergence

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