Infrared LED Performance & Integration Issues

Solve low sensitivity, false triggers, and range limitations in 850nm / 940nm IR systems.

Symptom Root Cause Verification Method Fix
Camera sees no IR illumination (black image at night) IR LED not driven, wrong wavelength (e.g., 940nm on monochrome cam), insufficient radiant power View through smartphone camera (shows 850nm glow); measure forward current Use 850nm for visible glow + camera sensitivity; ensure IF ≥ 100mA; add lens for focus
Short detection range (<1m) Low radiant intensity, poor optics, ambient IR interference Use IR power meter; test in dark room Select high-power IR LED (e.g., 1W); add secondary lens; modulate signal to reject noise
False triggers in proximity sensor Ambient sunlight saturation, crosstalk from nearby IR sources Cover sensor; test indoors vs outdoors Add optical bandpass filter (850±20nm); use pulsed drive with synchronous detection
IR LED overheats during continuous operation Inadequate heatsinking, excessive duty cycle Measure case temperature with thermal gun Reduce duty cycle to ≤50%; mount on copper pour; use pulse-width modulation (PWM)
Wavelength mismatch (e.g., sensor expects 940nm but gets 850nm) Incorrect part selection, bin drift Check datasheet λp; use spectrometer Verify part number; request wavelength test report from supplier
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