Detailed LRF1831C Specifications
The technical material below is retained for this model only. Do not transfer a range, pulse, interface, mechanical or safety value from another 1535 nm product.
Specifications
LRF1831C is a 1535 nm pulsed distance-measurement module. Its assigned laser source is ER300; receiver-component data below come from the supplied APD-A13B001 R01 document. The three specification levels describe different assemblies and measurement conditions.
1. LRF1831C module specifications
Source clarifications
The source J30J interface table labels two supply contacts “VCC 5V” but describes their function as “12V Input Positive”. The conflicting source labels are retained for traceability, not as wiring instructions. Use the confirmed connector record supplied with the ordered unit.
The dimension table states 113 × 76 × 90 mm and the drawing axes correspond to that envelope; the PDF has an inconsistent 125 × 100 × 70 mm caption below the drawing. The unrelated caption is not adopted as this model’s dimensions.
|
Project |
Performance Indicators |
|
Model |
LRF1831C |
|
Laser Wavelength |
1535 ±5 nm |
| Module laser-safety statement | Class I stated in the module document. Final accessible-emission classification applies to the complete configuration. |
|---|---|
|
Divergence Angle |
≤1.3 mrad |
|
Laser Energy |
≥350 μJ |
|
Main Functions of the Laser Rangefinder: |
a) Single-shot and continuous ranging; |
|
Receiver Lens Diameter |
Φ60 mm |
|
Measuring Range |
a) Under line-of-sight conditions, with visibility not less than 15 km and humidity not greater than 80% (at 30 °C), the ranging distance for Target 1 (5 m × 15 m) is ≥ 6,500 m. b) Under line-of-sight conditions, with visibility not less than 15 km and humidity not greater than 80% (at 30 °C), the ranging distance for a target with diffuse reflectance not less than 30% (20 m × 20 m) is ≥ 12,000 m. |
|
Minimum Range |
≤50 m |
|
Ranging Frequency |
0.5Hz ~10Hz |
|
Communication interface |
RS422 |
|
Ranging Accuracy |
±2 m |
|
Range Resolution |
≤0.1 m |
|
Precision Rate |
≥98% |
|
False Alarm Rate |
≤1% |
|
Pin-in-lead package model |
J30J |
|
Supply Voltage |
DC12 V |
|
Standby power consumption |
≤1.2W |
|
Average power consumption |
≤2 W |
|
Peak Power Consumption |
≤3W |
|
Weight |
≤410g |
|
Dimension (L×W×H) |
113×76×90mm |
|
Operating Temperature |
-40～+70 ℃ |
|
Storage Temperature |
-55～+75 ℃ |
|
Impact Resistance |
Meet the MIL-STD-810G testing standard |
|
Vibration Resistance |
Meet the MIL-STD-810G testing standard |
|
External plug-in XS3 |
Model：Molex51021-0500 |
Remark |
|
1 |
TTL RX |
3.3V |
|
2 |
TTL TX |
3.3V |
|
3 |
CTRL |
3.3V-5V power on, 0V power off |
|
4 |
+12V |
Power supply+ |
|
5 |
GND |
Power supply- |
|
Pin |
Definition |
Function |
Remarks |
|
1 |
GND |
Serial Port Ground |
|
|
2 |
GND |
12V Input Negative |
|
|
3 |
GND |
12V Input Negative |
|
|
4 |
VCC 5V |
12V Input Positive |
|
|
5 |
VCC 5V |
12V Input Positive |
|
|
6 |
RS422 RX+ |
Serial Port Receive + |
From the upper computer to the rangefinder |
|
7 |
RS422 RX- |
Serial Port Receive - |
From the upper computer to the rangefinder |
|
8 |
RS422 TX- |
Serial Port Transmit - |
From the rangefinder to the upper computer |
|
9 |
RS422 TX+ |
Serial Port Transmit + |
From the rangefinder to the upper computer |
Model-specific mechanical and interface drawings
2. ER300 source-laser specifications
| Parameter | Value |
|---|---|
| Optical wavelength | 1535 nm |
| Pulse energy | ≥300 µJ |
| Optical pulse width | 5 ns |
| Drive pulse width | ≤2.4 ms |
| Repetition rate | 1–10 Hz |
| Pulse stability | 10% (definition/statistical method not stated) |
| Raw beam diameter | 0.3 mm |
| Initial beam divergence | ≤7 mrad |
| Transverse mode | TEM00 |
| Operating / storage temperature | −40 to +65 °C / −55 to +75 °C |
| Package dimensions / mass | 25 × 8 × 6.8 mm / 8.5 g |
| Component electrical entry | 2 V, 12 A |
| Shock / vibration entries | 1500 G, 0.5 ms / 20–2000 Hz, 20 G |
| Stated service life | >1 million shots; test conditions not supplied |
The electrical entries describe the component drive, not the module supply input. Drive conditions and pulse-width definitions must follow the component document and the individual factory record. An optical pulse-width value is not a pump-drive duration.
3. APD-A13B001 receiver-component specifications
Small screens: swipe the table horizontally to read all measurement conditions.
| Parameter | Value | Measurement condition / scope |
|---|---|---|
| Device / active diameter | APD-A13B001 R01 / 200 µm | Supplied APD200 document, p1 |
| Detector spectral response interval | 800–1700 nm | Detector response; not the filter passband |
| Responsivity | 0.9 A/W minimum; 1.0 A/W typical | λ = 1550 nm; incident power = 1 µW; M = 1 |
| Dark current | 8 nA typical; 50 nA maximum | VR = VBR − 3 V; incident power = 0 |
| Multiplication factor | M ≥10 / M ≥30 | λ = 1550 nm; 1 µW; respectively VBR − 3 V / VBR − 1 V |
| −3 dB bandwidth | 0.6 GHz minimum; 1.25 GHz typical | M = 10; RL = 50 Ω |
| Breakdown voltage | 35–50 V | Reverse current = 10 µA; incident power = 0 |
| Capacitance | 1.8 pF typical; 2.0 pF maximum | VR = VBR − 3 V; f = 1 MHz |
| Breakdown temperature coefficient | 0.05 minimum / 0.11 typical / 0.15 maximum V/°C | Reverse current = 10 µA; dark; −55 to +85 °C |
| Operating / storage temperature | −40 to +85 °C / −55 to +125 °C | Component absolute-maximum table; not module environmental ratings |
| Maximum bias | VBR | Absolute maximum, not a recommended operating setpoint |
| Maximum forward / reverse current | 5 mA / 3 mA | Absolute maximum ratings, not continuous design targets |
| Filter centre wavelength | 1535 ±5 nm | Supplied filter table, p3 |
| Filter FWHM | <37 nm | Full width at half maximum |
| Transmission at centre wavelength | >90% | Filter specification, not total receiver throughput |
| Blocking specification | T <1%; source lists 400–1750 nm | Stop-band/transition edges are not numerically defined; the stated blocking span is not a guarantee at every wavelength. |
| Optical surface quality | 60/40 | Source label: surface quality; not a transmission value |
Responsivity is measured at 1550 nm; a value measured there is not silently relabeled as a measured 1535 nm value. Absolute maxima are stress limits. The filter document includes an illustrative spectrum, but does not define numerical transition edges or off-axis performance. No additional spectral guarantee is inferred.
Model-specific conditions and limits
Conditions are retained only when the source states them. They are not reconstructed from a nominal range or wavelength.
Operating conditions
Read a range value together with its test case
Target dimensions, surface reflectance and atmospheric visibility are part of the range specification. The beam may partly miss a small object, illuminate a sloped surface or return from several depths. A high-reflectance building result cannot establish the same distance to a smaller or darker object. Humidity and temperature conditions shown in a source table describe that test; visibility is not interchangeable with a guaranteed transmission percentage.
Measurement rate and electrical conditions
Measurement rate is the number of reported measurement opportunities per second. It is separate from optical pulse duration, receiver bandwidth and the time required for an individual return. Read operating power at the frequency and supply printed beside it. Peak power describes a different electrical requirement from average power; an average figure alone does not characterize supply transients.
Environmental and measurement context
A module temperature rating, laser-component temperature range and APD maximum rating describe different assemblies. Likewise, a named vibration standard does not disclose every method, mounting condition or acceptance threshold. Range repeatability, reported resolution and absolute accuracy are different quantities: a fine numerical display increment does not establish the error of the complete measurement.
Pulsed Time-of-Flight Ranging
Technical principle
A pulse, a return and a measured interval
Pulsed time-of-flight ranging measures elapsed time between an optical launch reference and a detected echo. The basic relationship is R = vΔt/2, where v is the speed of light in the propagation medium. The factor of two accounts for the outward and return journeys. The familiar expression using c treats propagation as approximately in air/vacuum; absolute metrology also considers refractive index and calibrated internal delays.
The measurement chain contains a pulsed source, transmit optics, an illuminated surface, collection optics, spectral filtering, a detector and timing electronics. ER300 supplies optical pulses. The module's output beam is described by its own optical specification after integration. A nanosecond laser pulse is not the same quantity as a millisecond pump-drive pulse or a hertz measurement rate.
Initial divergence and the integrated beam
A bare source has its own beam diameter and divergence. Collimating and expanding optics alter the relationship between beam size and angular spread. Therefore the component's initial divergence and the assembled module's transmitter divergence belong in separate rows. Finite beams still diffract, and real optics add aberrations, alignment error and clipping. A quoted angular value also needs a full-angle/half-angle convention and a beam-width definition before it supports a numerical footprint calculation. Those definitions are not invented where the product record omits them. Newport's optics explanation provides the general context.
Why the same laser can appear in different range classes
The laser source is one contributor to system performance. At a fixed, uniform irradiance at the receiver entrance, a circular unobscured collecting aperture has area A = πD²/4. With equal throughput and no clipping, collected optical power is proportional to that area. A larger receiver lens can therefore collect more of the available return. This is an area relationship under stated assumptions, not a range multiplier and not a test result for this product.
The return reaching that aperture also depends on transmitted energy, beam spread, object size and reflectance, surface orientation, atmospheric attenuation and optical transmission. Increasing collection area may collect additional background light as well. Receiver field of view, throughput, detector response and the decision process determine how much useful information remains. Consequently, models sharing ER300 can have different conditional range specifications, and their ranges should be compared using equivalent target and weather conditions.
APD conversion, filtering and timing
The supplied InGaAs APD generates photocurrent and provides internal avalanche multiplication. Its responsivity at M = 1 describes conversion before multiplication; the gain values describe a specified reverse-bias condition. Internal gain accompanies multiplication noise. Dark current, capacitance and bandwidth also matter, so the maximum tabulated gain is not automatically the best operating point. The specified gain conditions below breakdown describe linear APD operation, not evidence of single-photon Geiger-mode operation. Hamamatsu's detector guide explains these distinctions.
The narrowband filter transmits the useful wavelength region while rejecting specified out-of-band light. It does not reject background that lies inside its passband. Its centre transmission is not the throughput of the lens, window, filter and detector assembly together. A detector bandwidth measured at 50 Ω likewise does not specify the installed amplifier bandwidth or the finished rangefinder's accuracy.
Short distances, long distances and processing
At short distances, the return arrives near the launch event; optical overlap, prompt scatter and receiver recovery can limit the usable minimum distance. A strong close return can also exceed the linear region. At long distances, reduced return strength makes background, noise and signal discrimination more significant. These are different mechanisms, so good long-range performance does not imply a zero blind zone or a guaranteed result at every shorter distance.
In a threshold-based timing receiver, changes in pulse amplitude can shift the threshold-crossing time, called time walk. Calibration, multiple-return discrimination and signal estimation are general approaches discussed in the literature. Signal estimation and timing correction depend on the receiver architecture; no specific firmware method is claimed without a model-specific record. Reported multi-target capability alone does not disclose the underlying algorithm. Kurtti, Jansson and Kostamovaara examine receiver/TDC timing behavior in their own research hardware.
Pulse energy describes emitted energy per pulse; its effect cannot be separated from pulse width, divergence, optical losses, receiver threshold and the stated target/atmosphere conditions. It is not a substitute for a model-specific near- or long-range acceptance test.
Source-stated application context
Application labels indicate evaluation context, not automatic fitness for a finished system.
Both source cases require line of sight, visibility ≥15 km and relative humidity ≤80% at 30 °C; the larger diffuse target additionally specifies reflectance ≥30%. These substantial target sizes distinguish the record from other C-series range claims. They support evaluation for the stated large reference targets without establishing distances to smaller objects.
The module gives ≤1.3 mrad divergence, 0.5–10 Hz ranging, RS-422 and DC 12 V input, in a 113 × 76 × 90 mm envelope. The source review rejects a conflicting caption beneath the drawing in favor of the table and matching axes. Connector supply-label conflicts still require confirmation for the supplied hardware version.
Confirm short- and long-distance acceptance conditions
- Define minimum distance, target material, reflectance, size and incidence angle.
- Check receiver recovery, optical-axis overlap and strong-return handling at the intended near limit.
- Verify supply tolerance, peak current, grounding, interface levels, connector and timing with the ordered revision.
- For long-distance acceptance, state target geometry, visibility, weather, background and required detection probability.
- Test with the installed window, boresight, field of view, enclosure and thermal path rather than a bare module alone.
- Evaluate accessible emission, labels and failure conditions again for the finished laser product under IEC 60825-1.
Questions to resolve before design release
Which target distances are specified for LRF1831C?
The reviewed table lists ≥6500 m for a 5 × 15 m target and ≥12000 m for a 20 × 20 m diffuse target. Both require line of sight, visibility ≥15 km and relative humidity ≤80% at 30 °C. The larger diffuse target additionally requires reflectance ≥30%.
What conditions accompany the large-target distances?
Both cases require line of sight, visibility ≥15 km and relative humidity ≤80% at 30 °C. The 20 × 20 m diffuse target additionally requires reflectance ≥30%. The ≥6.5 km and ≥12 km values refer to different target sizes and must not be combined into an arbitrary-object range interval.
What does three-target reporting add to the product description?
The source lists single-shot and continuous ranging, together with three-target ranging and near/far target indication. Those are reporting functions, not independent claims about the distance to three objects in every scene. Each relevant target and return condition still needs to meet the applicable measurement requirements.
Which dimensions are retained for this model?
The source review retains 113 × 76 × 90 mm from the table and corresponding drawing axes. A separate 125 × 100 × 70 mm caption is inconsistent and is not adopted for LRF1831C. This avoids silently borrowing the neighboring model’s envelope for mechanical evaluation.
Is the module energy the same as the ER300 source entry?
The LRF1831C module table lists ≥350 µJ, while its separate ER300 component section lists its own source-laser energy. Those different specification levels remain distinct. The component name does not replace module output energy, establish a new target distance or resolve the source’s connector-label inconsistencies.
Product evidence and general technical context
The model PDF controls model claims. Public references below explain general engineering principles only.
- LRF1831C controlled module datasheetThe module-specific parameters, target conditions and version notes cited on this page.
- Practical application of pulsed “eye-safe” microchip laser to laser rangefindersGeneral context for pulsed 1535 nm rangefinder architecture and source/receiver selection.
- System Design of a Pulsed Laser RangefinderHow target properties, background and receiver design enter a pulsed-rangefinder performance assessment.