SPD1200M4 Ultra-Compact 905nm Laser Rangefinder Module for Thermal Imagers, Night Vision and Civil UAV Payloads

Technical Specifications

Functional Description

The system supports single measurement and continuous measurement functions.

3.1 Baud Rate Configuration
Allows modification of the serial communication baud rate.

3.2 Single Measurement
Triggers a single distance measurement to the target. For low-reflectivity targets, the system automatically repeats measurements until stable distance data is obtained. The final result is transmitted via the serial interface in the standard data format.

3.3 Continuous Measurement
In continuous measurement mode, the laser module performs repeated distance measurements on the target. The typical refresh rate can be set to 2 Hz, and the maximum refresh rate can reach 15 Hz.

Electrical Interface Definition

Mechanical Interface

Product Description

The SPD1200M4 is an ultra-compact 905nm laser rangefinder module developed for OEM integration into thermal imagers, night vision devices, telescopes, laser illuminators and lightweight civil UAV payloads. It is built as a civil electro-optical ranging core, emphasizing very low size and weight, low operating power and straightforward UART-TTL integration rather than the heavier architecture used in long-range military systems.

At the optical level, the module operates at 905nm ±5nm with a measuring range of 0.2m to 1200m, and the manual notes a maximum nighttime range up to 1500m. Accuracy is specified as ±0.3m below 100m, and ±0.3m + d×0.7‰ from 100m to 1200m, where d is distance. The valid measurement rate is ≥98%, the false alarm rate is ≤1%, beam divergence is <4mrad, and the receiving aperture is 5.0mm × 7mm. Those figures make the SPD1200M4 a genuine micro-SWaP 905nm ranging core for electro-optical products that need kilometer-class capability without a bulky optical block.

One of its strongest system-level advantages is the 2–15Hz ranging frequency, with 4–15Hz adaptive operation also supported. The module provides both single measurement and continuous measurement. In single mode, when the target reflectivity is low, the system automatically repeats internal measurements until stable distance data is obtained before returning the result. In continuous mode, the typical refresh rate is 2Hz, while the maximum can reach 15Hz. That makes it well suited to handheld optics, portable observation devices and compact UAV payloads that need a balance between response speed and low power.

Electrically, the SPD1200M4 uses a UART-TTL communication interface with a default baud rate of 115200bps and a supply voltage of 3.3V to 5V. Startup time is ≤200ms, startup inrush current is about 380mA, average operating power is about 0.45W, and maximum operating power is ≤0.75W. That SWaP profile is particularly attractive for battery-powered optics and very small airborne payloads. Comparable 905nm OEM modules on the market are also commonly positioned around handheld optics, thermal imaging and compact UAV integration, which matches the practical niche of this product.

The communication protocol is intentionally simple for embedded development. The module uses an 8-byte frame with 0x55 0xAA header bytes, a function code, four data bytes and checksum. Supported functions include single-shot ranging, continuous ranging, stop ranging, optional angle measurement for versions fitted with an angle sensor, power-on self-test, baud-rate configuration and LD constant-ON mode for development. Distance data is returned in hexadecimal as the actual value multiplied by 10, so the host can reconstruct the result with one decimal place. The manual also notes that baud-rate changes take effect only after reboot and that LD constant-ON mode should not be enabled for long periods.

Mechanically, the SPD1200M4 is extremely compact at 9.45mm × 16.8mm × 27.85mm and weighs ≤6g. It uses a 6-pin electrical interface with SW-SHOT, RXD, TXD, reserved I/O, VCC and GND. The guide specifies that the Enable pin must be pulled LOW (connected to GND) during operation, a small but important detail for stable bring-up in host electronics. Because the body is narrow and rectangular, it fits more easily into slim optical channels, compact monoculars, thermal viewer housings and micro payload bays than older cylindrical modules.

The environmental envelope is practical for civil outdoor equipment: −20°C to +60°C operating temperature, −30°C to +70°C storage, IP67 protection inside the lens cavity, 1000g/ms shock resistance along the optical axis, 5–50–5Hz, 2.5g vibration resistance, and MTBF ≥1500h. These characteristics fit embedded electro-optical systems used in field conditions rather well.

For front-window integration, the manual recommends H-K9L optical glass or fused silica, wedge-angle tolerance ≤3′, surface roughness around Ra 0.012, and an AR coating optimised for 855–955nm with transmittance ≥99.5%. After hydrophobic or hard coatings, total transmittance should remain ≥98%. The recommended optical-window thickness is around 2–4mm, the transmit optical axis should be parallel to the window normal, and the air gap should remain below 0.5mm to minimize additional loss and back-reflection. In plain English: the optics want a clean window and very little nonsense between them and the target.

The use notes also clarify real-world ranging behaviour. Under the reference condition—a medium-reflectivity target such as a building wall, perpendicular incidence, clear weather and no direct sunlight—the module achieves nominal performance. The manual also notes representative target behaviour: high-reflectivity targets such as highway traffic signs, medium-reflectivity building walls, and low-reflectivity targets such as trees or animals all produce different maximum ranges, while rain, fog, snow and haze reduce usable distance. For long-distance measurement, tripod mounting is recommended.

Taken together, the SPD1200M4 is best understood as a micro 905nm ranging core for civil electro-optical integration: tiny enough for slim optics and embedded devices, strong enough for 1200m-class daytime and 1500m-class nighttime performance, and simple enough for quick UART-based secondary development in night vision, thermal imaging, portable observation devices, border security monitoring, smart water conservancy and civil UAV payloads. Those application patterns also align with how 905nm compact modules are commonly positioned across current OEM listings and electro-optical integration pages.