Photon Matrix is a real pre-order product, not a cheap AliExpress laser turret. Its maker describes LiDAR, millimeter-wave radar, AI vision, galvanometer aiming and either a 450 nm or 976 nm strike beam. The official store currently lists the infrared model at $988 and declares an internal IEC 60825-1 Class 4 diode. Independent reporting says mandatory laser-safety certifications were still in progress in June 2026. Those facts make the laser subsystem the wrong thing to copy at home.
This build keeps the useful experience—detect, intercept and count—but changes the interceptor to enclosed airflow. A mosquito-sized insect enters a matte-black tunnel 20-40 cm long. An 850 nm board shines through a diffuser across one narrow detection plane while an IR-sensitive camera watches for a moving silhouette. A downstream fan pulls air through a removable fine-mesh cup, so the insect reaches the mesh before the guarded blades rather than passing through a propeller.
Build the air path before the software. Print or cut a square tunnel, seal light leaks, put a tapered inlet at one end, then mount the capture cup, a light anti-backflow flap, fan and exhaust guard at the other. With the electronics disconnected, use incense smoke outside the inlet to confirm smooth inward flow and no recirculation. The cup must be removable only when power is off, and both sides of the fan need finger guards.
For the first firmware milestone, run the fan continuously at low speed and use the ESP32-S3 camera only as a counter. Downsample frames, maintain a slowly updated background, reject blobs outside a calibrated pixel-area range and require motion in three consecutive frames before recording an event. The inexpensive OV2640 uses a rolling shutter and can blur or miss fast crossings, so treat its count as a tuning signal rather than ground truth. Do not call this species identification: dust, moths and other small insects can trigger it. Save only a short event counter or low-resolution diagnostic frame, not continuous room video.
Only after capture works mechanically should you add the air-defence effect: drive a four-pin fan's PWM control through an open-collector transistor, hold the fan at a quiet baseline and ramp it for several seconds when a candidate crosses the detection plane. Wire 12 V directly to the fused fan and illuminator branch; feed the ESP32 from the buck converter's adjusted 5 V output. Connect the fan PWM lead to the transistor collector, emitter to ground and the ESP32 GPIO to the base through a 1 kΩ resistor. Join grounds at one point, verify the buck output with a meter before connecting the camera and never feed the fan's 12 V line into an ESP32 pin. A commercial mosquito lure can improve attraction, but the device should make no public-health or bite-reduction promise without a controlled field test.