A night-vision monocular or a thermal clip-on sight has a very small weight and volume budget, most of which is already spoken for by the image intensifier tube or the microbolometer array, the objective optics, and the housing needed to keep all of it environmentally sealed. Adding ranging capability means fitting a complete DToF measurement system — emitter, receive optics, APD, timing electronics — into whatever budget is left. That constraint, more than any other, shapes how these modules are designed.
Why the module has to be small
Our N-series exists specifically for this envelope. The SPD1200N0 and the SPD1200N2 are Ø15.7 × 21.3 mm cylinders with a sealing groove, each weighing about 5 g. The SPD1200N4 publishes the same range and accuracy figures on a 7.7 × 16.7 mm envelope — the source states only those two dimensions — at about 5 g as well. All three range 0.2–1,200 m at ±0.3 m to 100 m, and the N0 and N2 tables add a 1,500 m maximum at night — full ranging performance, not a stripped-down version, in a package that can sit alongside an intensifier tube without materially changing the device’s balance or bulk.
Where the housing has more room — a handheld monocular rather than a helmet-mounted clip-on, for instance — the SPD1200S2G trades size and mass for capability: a 24.6 × 11.4 × 26.3 mm square body at about 10 g, a 0.1 m minimum range, ±0.2 m accuracy out to 400 m, and an integrated gyroscope for applications that also need attitude data.
| Model | Size | Weight | Range | Accuracy |
|---|---|---|---|---|
| SPD1200N0 | Ø15.7 × 21.3 mm | ≈ 5 g | 0.2–1,200 m (1,500 m night) | ±0.3 m (≤100 m) |
| SPD1200N2 | Ø15.7 × 21.3 mm | ≈ 5 g | 0.2–1,200 m (1,500 m night) | ±0.3 m (≤100 m) |
| SPD1200N4 | 7.7 × 16.7 mm | ≈ 5 g | 0.2–1,200 m | ±0.3 m (≤100 m) |
| SPD1200S2G | 24.6 × 11.4 × 26.3 mm | ≈ 10 g | 0.1–1,200 m (max 1,400 m) | ±0.2 m (≤400 m) |
Why 905 nm and Class 1 specifically fit this category
Night-vision and thermal devices are, almost by definition, aimed at people, vehicles and animals in low light by an operator who is often moving, sometimes untrained, and not always able to verify a clear line of fire for the beam. The spec tables for these modules record a Class 1 laser safety class — IEC Class 1 on the SPD1200N0, SPD1200N2 and SPD1200S2G, IEC Class I on the SPD1200N4 — as stated in the model manual: a manufacturer declaration about the module as delivered, not a third-party test report, and the assessment of the finished device you build around it is a separate exercise that stays with you. Class 1 is a limit on accessible emission, not a property of the wavelength; our article on how IEC 60825-1 Class 1 applies to a 905 nm module sets out what that does and does not cover. A Class 1 accessible-emission limit is still a meaningfully different risk profile from a higher-power, higher-class emitter, and it’s the reason this entire product category is built on the 905 nm, silicon-APD platform rather than a higher-energy alternative.
How it integrates without touching the optical path
The ranging module doesn’t sit inside the imaging chain — it doesn’t interact with the intensifier tube’s photocathode or the bolometer array at all. It’s mounted alongside or behind the objective, pointed roughly co-axially with the sight’s optical axis, and reports distance independently over its own UART-TTL line to the device’s host MCU. The host is then responsible for reading the frame and rendering a distance readout on the display, or feeding it into a ballistic/reticle compensation calculation — the ranging module’s job ends at handing over a validated number.
Environmental durability for field use
These devices live outdoors, get dropped, and see temperature swings — so the ranging module has to match that duty cycle. Across the line: IP67-rated lens cavities keep dust and moisture out of the optical path, operating temperature ranges typically span -20 °C to +60 °C (with -40 °C options on several models), and shock/vibration ratings around 1000 g/ms with 5–50–5 Hz / 2.5 g cover field handling and the vibration seen in handheld thermal scopes and other outdoor optics. Reliability is specified as MTBF ≥ 1,500 h in the SPD1200N0, SPD1200N2 and SPD1200S2G spec tables; the SPD1200N4 table publishes no MTBF figure, and we do not lend it a sibling’s. Assembly, optical alignment, calibration, functional verification and final acceptance are all performed in-house in Chengdu.
Mounting position and what it doesn’t have to clear
Because the module works independently of the imaging chain, it doesn’t need to share a lens system, a boresight adjustment, or an optical coating stack with the intensifier tube or the microbolometer. That gives the mechanical designer real freedom in where it sits — beside the objective, above it, or built into the same housing wall as the battery compartment — as long as its own small aperture has an unobstructed, roughly co-axial view out through the front of the device. On a device built around the SPD1200S2G, whose integrated gyroscope publishes a Euler-angle range of roll ±180°, pitch ±90° and yaw ±180° with 0.3° tilt accuracy, that same independence means the attitude sensor can be referenced to the housing’s own mechanical axis without needing to be co-registered with the optical path at all.
Choosing between the N-series and the SPD1200S2G
If weight and volume are the binding constraint — a helmet-mounted or clip-on device — start with the N-series and its roughly 5 g envelope. If the housing has a bit more room and you need attitude data, a 0.1 m minimum range or the tighter ±0.2 m figure out to 400 m, the SPD1200S2G is the better starting point at about 10 g. Either way the interface is UART-TTL, so switching between them later doesn’t mean redesigning your host integration from scratch.
If you’re not sure which envelope your housing can actually absorb, send us the available cavity dimensions and your target range — that’s usually enough for us to point you straight at the right series rather than working through the whole catalog by trial and error.