Voxtel Opto ROX APD Photoreceiver Series User manual

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USER MANUAL
PHOTORECEIVERS, LASERS,
LASER RANGEFINDERS, LRF MODULES,
AND LRF SYSTEM-INTEGRATOR KITS
Voxtel Literature LRF User Manual 26April2019_ed06Dec2019©. Voxtel makes no warranty or
representation regarding its products’ specific application suitability and may make changes to
the products described without notice.
Voxtel Inc. 15985 SW Schendel Avenue, Beaverton, OR 97006, USA
www.voxtel-inc.com

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CONTENTS
Safety.............................................................................................................................................................................3
Safety Symbols ..........................................................................................................................................................3
Handling Precautions ................................................................................................................................................4
Introduction...................................................................................................................................................................6
Cautions, Warnings, and Notes .................................................................................................................................6
Organization ..............................................................................................................................................................6
Resources .................................................................................................................................................................. 6
ROX APD Photoreceiver Products..................................................................................................................................7
Precautions................................................................................................................................................................ 7
Setup and Operation .................................................................................................................................................8
Adjusting the Voltage Threshold level..................................................................................................................9
Configuring Time-variable Threshold (TVT) ..........................................................................................................9
Changing the Decay Time on the Voltage Threshold............................................................................................9
Calibrating for Range Walk ...................................................................................................................................9
Troubleshooting ......................................................................................................................................................10
ROX APD Photoreceiver Evaluation Board ..............................................................................................................10
Initial Configuration ............................................................................................................................................11
Operation............................................................................................................................................................12
Configuring Time-variable Threshold (TVT).........................................................................................................12
DPSS Lasers and Laser Driver Boards...........................................................................................................................14
Precautions.............................................................................................................................................................. 14
Assembly, Configuration, and Operation ................................................................................................................15
Use of non-Voxtel laser driver boards.....................................................................................................................18
Disassembly/Storage ...............................................................................................................................................19
Troubleshooting ......................................................................................................................................................19
LRF System-Integrator Kit ............................................................................................................................................20
Precautions.............................................................................................................................................................. 20
Assembly and Configuration ...................................................................................................................................21
LRF OEM Module .........................................................................................................................................................25
Precautions.............................................................................................................................................................. 25
Assembly, Configuration, and Operation ................................................................................................................26
LRF Systems Operation................................................................................................................................................30
Precautions.............................................................................................................................................................. 30
Connectivity.............................................................................................................................................................30
Direct Cabled Connection to LRF system board .................................................................................................31
ISM Connection to LRF System Board.................................................................................................................31
Communication .......................................................................................................................................................31
Receiver Gain Configuration....................................................................................................................................33
Position LRF System.................................................................................................................................................34
Receiver Threshold Configuration...........................................................................................................................34
Ranging Commands.................................................................................................................................................35
Operational Examples .............................................................................................................................................37
Single-pulse Range Operation.............................................................................................................................37
Multi-Pulse Range Operation..............................................................................................................................39
Auxiliary Board ........................................................................................................................................................39

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Updating Module Software and Firmware..............................................................................................................40
Installing the LRF Commander Software ............................................................................................................40
Loading the Device Firmware .............................................................................................................................43
Appendix A—Unpacking, Inspection, and Cleaning.....................................................................................................45
Unpacking................................................................................................................................................................ 45
Inspection and Cleaning ..........................................................................................................................................46
Inspection ...........................................................................................................................................................46
Window Cleaning Techniques.............................................................................................................................46
Appendix B—LRF Detection Threshold........................................................................................................................48
Appendix C—Auxiliary Board.......................................................................................................................................49
Setup, Configuration, and Calibration.....................................................................................................................50
Mounting and Enclosure.....................................................................................................................................51
Sensor Initialization and De-initialization ...........................................................................................................51
Sensor Configuration ..........................................................................................................................................51
System Operation....................................................................................................................................................54

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SAFETY
Before unpacking the product, read and learn all safety and handling information provided in this section. Whenever
unpacking, handling, operating, moving, or storing the product, ensure all guidelines in this section are met.
References
•EN/IEC 60825-1 Ed.2 2007
•Laser Notice No. 50, dated June 24, 2007
SAFETY SYMBOLS
When handling a Voxtel laser product, the labels and hazard descriptions below apply. Due to size limitations, labels
do not appear on the product.
With the exception of the ESD warning label, the following labels are provided for application by the assembler or
end user of the product. Proper product labeling of the fully assembled product is required in order to meet FDA
certification guidelines. Proper labeling provides the user with appropriate warnings and product information when
applied in the following manner.
•Labels provided must be permanently fixed, legible, and visible according to their purpose.
•Labels provided must be read without the necessity for human exposure to laser energy in excess of the limits
associated with Class 1.
Further explanation can be found in IEC 60825-1 Ed.2, sec 5.1
Explanatory Label
This product is a Class 1 laser product as defined by EN/IEC
60825-1 2007.
Non-Interlocked Protective Housing Label
The eyesafe, microminiature DPSS laser contains a Class 4 laser
diode. There are no user-serviceable parts on any of the items
supplied. Do not attempt to open the laser to attempt
maintenance, service, repair or reconfiguration of any kind.
Certification Label
This laser complies with U.S. FDA performance standards for
laser products except for deviations pursuant to Laser Notice
No. 50, dated June 24, 2007.
Manufacturer’s Identification Label
Manufacturer, address, product and serial number.

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ESD Warning Label
Handling this product requires ESD precautions.
HANDLING PRECAUTIONS
This section applies to all Voxtel LRF products.
For all units
equipped with a laser:
I
n addition to the requirements below, adhere to the
requirements of:
•
“DPSS Lasers and Laser Driver Boards” section of this
manual
•
Safe use of laser protocols using ANSI Z136.1-2014
•
ESD prevention protocols using
ANSI-ESD-S20.20-2014 as a guide
For units
not equipped with a laser:
In addition to
the requirements below, adhere to the
requirements of:
•
ESD prevention protocols using
ANSI-ESD-S20.20-2014 as a guide
⚠Warning
•For all units equipped with a laser, failure to follow laser protocols and precautions when handling the product
may result in personal injury and/or damage to the product.
⚠Caution
•Failure to follow ESD protocols and precautions when handling the product may result in damage to the product.
A single electrostatic discharge (ESD) event can cause catastrophic or latent device failure.
ESD Precautions
For all units that have a standalone laser:
•When Not in Use: Electrically short the laser anode and cathode electrical leads to prevent ESD damage.
oFor lasers with connectors attached, insert the shorting pin in the connector.
oFor lasers without connectors, twist the exposed conductive wires together.
•When Making the Connections: 1) do not connect the laser to a function generator, or other pulse
generator, with the pulse generator emitting pulses; 2) connect 5V to the laser diode driver before
attaching laser wires. Disconnecting and reconnecting the 5V with the laser wires attached to the anode
and cathode may damage the laser.
For all units (including those equipped with a laser):
•Clean, Static-free Environment: Do not open the package in an unclean environment; handle the product
only in a clean, static-free work environment, such as a grounded workbench or surface.
•Continuous Grounding: Ensure all persons and tools that may contact the product are continuously
grounded.
•ESD-protective Clothing/Accessories: When handling the product, wear: 1) a grounded wrist strap; 2) ESD
protection; and 3) ESD-safe (static-dissipative) lint-free (nonshedding) gloves. If any oil or grease is
apparent on the gloves, replace the gloves.

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•ESD-protective Container:When transporting the product beyond the confines of the workbench, place it
in an ESD-protective container that restricts product movement within the container, such as the original
shipping container, an antistatic bag, or a grounded cart.
•Powered-off for Connections: When making connections, ensure the product power supply is off. Do not
connect a product to a laser diode when the power supply voltage is on.
Additional Handling Protocols and Precautions
For all units (including those equipped with a laser):
•When placing or positioning the product, use a light touch.
•Except as described in “Appendix A—Unpacking, Inspection, and Cleaning,” do not allow anything to
contact the transmit window of a laser or the receive window of a photoreceiver.
•Handle the product using thumb and forefinger as shown:
For lasers, hold the top of the laser casing—
above the mounting flanges.
⚠
Caution
•Do not bend the laser mounting flanges.
The mounting f
langes are designed as
flexures to reduce torque effects
during
mounting. If not handled correctly, the
mounting flanges may become bent.
For photoreceivers, receivers are best handled by
holding with thumb and forefinger across the
diameter of the TO-8 can.
⚠
Caution
•Do not allow pins to bend
Take care when mounting, handling,
or placing
the product. If pins need to be straightened
,
use a standard pin-straightening tool.
•During handling, wear clean lint-free gloves to avoid contaminating the window.
⚠Note
•Do not touch the product with bare hands.
Any oil or grease that contacts the window can negatively impact performance; oil or grease that
contacts the product casing can negatively affect cosmetic appearance.
Additional Notes
⚠Note
•Voxtel is not responsible for the setup and operation of non-Voxtel supplied equipment.
⚠Note
•The product may look different than shown. Refer to the drawings on the datasheet.

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INTRODUCTION
This user manual provides the information necessary to operate the ROXTM laser ranging photoreceivers, pulsed
diode-pumped solid-state (DPSS) lasers, electronics, and rangefinding or lidar products.
CAUTIONS, WARNINGS, AND NOTES
In this handbook, the following conventions are used:
⚠Warning
•Failure to follow this guidance may result in injury.
⚠Caution
•Failure to follow this guidance may result in damage to the equipment.
⚠Note
•Failure to follow this guidance may result in sub-optimal performance of equipment.
ORGANIZATION
This manual is generally organized by product. For devices that integrate multiple products as components—such as
the laser rangefinding (LRF) modules, which integrate ROX APD photoreceivers, DPSS lasers, and electronics—
information is available about the integrated product and additional information is available by component. For
example, while an integrated LRF module has its own section, specific information about the laser is provided in the
laser section and specific information about the photoreceiver is provided in the photoreceiver section of this
manual.
Information that is universal to all LRF products is provided in the following sections of this user manual:
•Safety
•Appendix A—Unpacking, Inspection, and Cleaning
For all products, before unpacking the product from the shipping package, ensure all safety and handling conditions
are met.
RESOURCES
•Product Datasheets
oIndividual product datasheets are available via the relevant product links from http://voxtel-
inc.com/products/.
oAsingle-file compilation of all LRF product datasheets is available at http://voxtel-
inc.com/files/LRF-Product-Catalog.pdf.
•Mechanical drawings and solid models are available at http://voxtel-inc.com/voxtel-news/user-resources/.
•Latest LRF firmware and software are available at http://voxtel-inc.com/voxtel-news/user-resources/.
•Voxtel Technical Notes on Laser Rangefinding—These technical notes are to help users understand how to
model, configure, integrate, and operate the laser-ranging products for specific applications. The technical notes
are available via the Technical Papers link on the Resources page at Voxtel-Inc.com.
•Voxtel’s Software Interface Control Document for Laser Rangefinder Modules, Kits, and Components (software
ICD) is available at http://voxtel-inc.com/files/LRF-Software-ICD.pdf.
•This user manual is available at http://voxtel-inc.com/files/LRF-User-Manual.pdf.

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ROX APD PHOTORECEIVER PRODUCTS
References
•ROXTM APD Photoreceiver Product Datasheet—Contains required operational information for connecting and
using the ROX APD photoreceivers, as well as information on the ROX APD Photoreceiver Evaluation Board.
•Voxtel Technical Notes on Laser Rangefinding—These technical notes are to help users understand how to
model, configure, integrate, and operate the laser-ranging products for specific applications. The technical notes
are available via the Technical Papers link on the Resources page at Voxtel-Inc.com.
PRECAUTIONS
APD photoreceivers are sensitive to damage by ESD or other voltage transients. ESD-mitigating procedures are
required when handling the photoreceivers. Before handling the equipment, read and become familiar with the
safety and handling information below and in the “Safety” section of this manual.
⚠Caution
•Failure to follow ESD procedures when handling the photoreceiver may result in damage to or destruction of the
photoreceiver.
•Do not connect the photoreceiver with the power-supply voltage powered on.
•Do not direct or focus laser light directly on the ROX APD photoreceiver.
APD photoreceivers are sensitive to being damaged by large optical signals. For optical damage threshold limits,
refer to the product datasheet.
•Do not direct high-pulse-energy lasers or high-average-power pulsed lasers directly onto the APD photoreceiver.
For testing, a sufficient signal level can be achieved by pointing the laser source at a very diffuse source, so that
only a diffuse reflection of the laser light reaches the photoreceiver. Alternatively, neutral density filters can be
placed in front of the laser and photoreceiver to attenuate the optical signals at the photoreceiver.
⚠Note
•Voxtel is not responsible for the setup and operation of non-Voxtel supplied equipment.

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SETUP AND OPERATION
1. Read and adhere to the safety and handling protocols described at the start of this product section and in the
“Safety” section of this manual.
⚠Warning
•Failure to follow the precautions and procedures in the “Safety” section of this manual may result in
catastrophic damage to the system.
2. Unpack, inspect, and (if necessary) clean the product as described in “Appendix A—Unpacking, Inspection, and
Cleaning.”
3. Consult the photoreceiver datasheet for electrical and optical interfacing to the photoreceiver.
4. Configure a printed circuit board to provide the electrical input and output signals shown on the datasheet.
5. APD photoreceivers are factory-configured to default on power up to Mode 1, which sets the APD to operate
with a gain of M= 1. For a description of the photoreceiver operating modes, refer to the ROX APD
Photoreceiver Product Datasheet.
6. Before integrating the photoreceiver in the circuit, verify that the electrical interfaces meet the specifications
of the datasheet.
7. If the photoreceiver analog output is being used, verify that the termination of the output is 50 ohms.
8. Configure the controller to send start commands to the photoreceiver with the pulse-width encoding shown
on the datasheet.
9. Adjust the voltage threshold (Vth) to 0.55V.
10. Power-off the circuit and insert the photoreceiver.
11. Darken the operating environment or place a shroud or other covering over the photoreceiver, so that
ambient lighting will not increase the noise floor.
12. Power-on the circuit, monitoring the power lines.
13. Ensure the current draw of the supplies are within the expected values on the datasheet.
⚠Note
•The APD photoreceiver output will not respond to DC light sources.
14. Send a START command for Mode 1 (M= 1) operation.
15. Continue to send START commands at regular time intervals (e.g., every few seconds) so that the APD bias is
adjusted to accommodate temperature changes. Do not allow the temperature of the APD photoreceiver to
lower more than a few degrees Celsius.
⚠Caution
•Failure to monitor temperature and re-bias the APD by sending START commands can damage the product.
If the temperature of the photoreceiver is changed by more than a few degrees Celsius, the change in the APD
gain characteristics can cause the APD to go into sustained avalanche breakdown, resulting in permanent
damage to the photoreceiver.
16. Test the photoreceiver to check if it is operational using one of the following methods:
•While operating without a pulsed light source, adjust the Vth bias down until false hits begin to be returned from
the digital outputs. This will occur between 0.4V and 0.5V; or
•Monitor the analog output and confirm there is a signal at the output when the laser source is firing.
17. Power off the laser source and reduce Vth in small steps from 0.6V until desired false-alarm rate (FAR) is
reached.
18. If using the optional evaluation board, setup and configure as described in “ROX APD Photoreceiver Evaluation
Board,” later in this section.

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ADJUSTING THE VOLTAGE THRESHOLD LEVEL
Proper management of the detector voltage threshold level is critical for optimal operation of the photoreceiver.
The threshold settings, during the ranging event, set: the voltage level in the detector that determines the probability
of detecting the return laser pulses; and the false-alarm rate (FAR) of the photoreceiver. Generally, low voltage
threshold settings allow for a high probability of pulse detection with a higher FAR, and high voltage threshold
settings allow for a lower probability of pulse detection, with a lower FAR.
To optimize the voltage threshold for various applications, refer to Voxtel’s Technical Notes on laser rangefinding.
CONFIGURING TIME-VARIABLE THRESHOLD (TVT)
While synchronizing to the outgoing laser pulse, reduce Vth from a voltage bias level of Vth_high to a voltage bias level
of Vth_low. An RC circuit in the APD photoreceiver will drop the threshold with the decay time specified in the
datasheet. The RC decay time is also user-configurable.
In the standard configuration, the photoreceiver includes an RC time delay circuit that allows the user to change the
threshold level while ranging. This allows the photoreceiver detection probability to change as a function of range,
so that probability of detection of a target is somewhat normalized as a function of range.
A time-variable threshold (TVT) can be achieved by changing the Vth level from a high voltage level to a low voltage
level. The threshold begins to lower immediately once the Vth level is switched from the end system. This is typically
done when the T0 pulse is detected.
The photoreceiver is designed to allow for TVT, which allows for the detection threshold to change over a decay
time. The specific decay-time constant at which the detection threshold lowers as a function of time is included in
the photoreceiver datasheet. RC delay circuits tailored to user-specific requirements can be accommodated (contact
Voxtel for details).
To cause a TVT, set Vth to the highest threshold voltage level (Vth_high) optimal for detecting the near-field optical
pulse returns. Vth_high is generally set to between 0.65V and 0.70V.
•Vth high should be set so that the outgoing pulse can be detected.
•Vth low should be set to the desired false alarm rate of the end system.
When Vth is switched from high to low the voltage threshold is dropped to a lower voltage, Vth_low.
Vth_lowdetermines pulse-detection probability and false-alarm probability at the end of the TVT decay time, which
means it must be set specifically for the application requirements. The low voltage threshold, Vth_lowis generally
between 0.45V and 0.6V.
CHANGING THE DECAY TIME ON THE VOLTAGE THRESHOLD
The time constant changes the threshold as follows:
Vth (τ) = Vth_high - (Vth_high – Vth_low)·e-τ⁄R·C
When the external value of Vth is changed from one value to another—e.g., from a high voltage level, Vth_high, to a
low voltage level, Vth_low—as configured at the factory, the internal threshold Vth(τ) changes according to the RC time
constant. The RC value can be found on the datasheet. It may be possible to modify the RC time constant by adding
a resistor to the circuit, outside of the TO-8 package. For details, contact Voxtel.
CALIBRATING FOR RANGE WALK
Range walk is the systematic dependence of the range accuracy on the return pulse amplitude. The effects of range
walk can be mitigated in the photoreceiver by approximating the pulse amplitude by recording the leading-edge and
falling-edge threshold crossings of the return laser pulse. The difference between the times of the falling edge and