If you’re an engineer staring at a blank spec sheet trying to decide between a pulsed IR emitter and a steady-state IR source, you’re not alone. I’ve been in exactly that spot more times than I can count — usually at 2 a.m. with coffee going cold. Let’s cut through the marketing fluff and talk about what actually matters when you’re picking one for your next design.
First off: What are we even talking about?
A steady-state IR source is basically the “always-on” type. Think of an incandescent bulb for the infrared world — it just sits there glowing at a constant temperature. Simple, reliable, been around forever.
A pulsed IR emitter, on the other hand, is more like a strobe light. It flashes super bright for tiny bursts (microseconds to milliseconds) and then chills out. Most modern ones use LED or laser diode tech under the hood, sometimes with a phosphor, sometimes not.
That’s the 30-second version. Now let’s dig into when each one makes your life easier (or harder).
Power Consumption & Heat — The Real Budget Killer
If your system runs on batteries or you have to deal with heat sinking in a sealed box, this is usually the first fight.
| Aspekt | Steady-State IR Source | Pulsed IR Emitter |
|---|---|---|
| Average power | 100% duty = 100% power | Often <5% of peak (depends on duty cycle) |
| Peak power | Same as average | Can be 50–200× higher than average |
| Heat generated | Constant, high | Mostly during pulse → way easier to manage |
| Typical example | 500 mW continuous | 50 W peak, 1% duty → 500 mW average |
Real project example (details changed a bit for NDA reasons): We had a handheld gas analyzer a couple years ago. Customer started with a steady-state filament source — 800 mW continuous. Battery life? About 3 hours. Switched to a pulsed LED-based emitter at 1% duty cycle → same signal-to-noise, battery now lasts 30+ hours. The mechanical guys actually hugged us.
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Lifetime and Reliability
Filament-based steady-state sources are tough, but thermal cycling is their enemy. Turn them on/off a lot and they die fast.
Pulsed emitters (especially solid-state ones) laugh at thermal cycling because they’re off most of the time.
Rough numbers from real manufacturers (Osram, Laser Components, etc.):
- Incandescent IR sources: 5,000–40,000 hours at full power (drops fast if you dim them)
- LED-based pulsed IR: 50,000–100,000+ hours easy
- Laser-diode pumped phosphor: 20,000–50,000 hours
One customer was replacing steady-state bulbs every 6 months in an outdoor sensor. Went pulsed → still on the original emitter after 4 years.
Signal-to-Noise and Detection Range
Here’s where pulsed usually wins big.
Because you can overdrive the crap out of a pulsed emitter for short bursts, you get insane peak radiance. That means better signal through smoke, dust, rain, whatever.
Lock-in amplifiers or simple gated detectors love pulsed sources — background light gets ignored completely. Steady-state? You’re fighting sunlight, blackbody radiation from everything warm, etc.
Actual measurement I did last year:
- Same optics, same InGaAs detector
- Steady-state source at 5 m: SNR ≈ 800:1
- Pulsed at 1% duty, 100× peak power: SNR ≈ 25,000:1 at 5 m
- And we could push reliable detection out to ~18 m vs ~7 m before.
Cost — Yeah, We Have to Talk About Money
Upfront:
- Basic steady-state IR bulb: $10–$50
- Decent pulsed IR emitter module + driver: $80–$400
But lifetime and power costs usually flip the equation in 6–18 months for anything that runs a lot.
So… Which One Should You Actually Pick?
Quick decision cheat-sheet I actually use with customers:
| Anmeldung | Best Choice | Why |
|---|---|---|
| Low-cost, lab prototype, don’t care about power | Steady-state | Cheap, simple driver |
| Battery powered anything | Pulsed | No contest |
| Outdoor / long-range NDIR gas sensing | Pulsed | Sun rejection |
| High-temperature blackbody reference | Steady-state | Stable spectrum |
| Fast modulation (>10 kHz) | Pulsed (laser/LED) | Rise/fall times |
| Medical — skin contact safety concerns | Usually steady-state | Lower peak intensity |
Real-World Combo We Ship A Lot
Funny enough, a bunch of our customers end up using both in the same system. Steady-state for calibration or reference channel, pulsed for the measurement channel. Best of both worlds.
Speaking of real products — if you’re doing any kind of scanning or fast modulation, check out our Galvanometer Scanner Light Source. It’s built from the ground up for pulsed operation with stupid-fast rise times and integrates cleanly with galvo mirrors. We’ve had people use it for everything from LIDAR test beds to high-speed spectroscopy.
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FAQ – Stuff Engineers Actually Ask Us
Q: Can I just take a steady-state source and chop it with a shutter to make it pulsed?
A: Technically yes, but you’ll murder the lifetime super quick from thermal shock, and you still have all the average-power heat. Mechanical shutters also add noise and wear. Not recommended unless it’s a one-off lab thing.
Q: Are pulsed emitters safe for eye safety calculations?
A: Actually often easier to make Class 1. Because average power is low even if peak is crazy high. IEC 60825-1 loves short pulses — you get way more wiggle room.
Q: What’s the catch with pulsed?
A: Driver complexity and potential EMI if you’re not careful. But any decent vendor (like us) gives you a clean board-level solution these days.
Look, at the end of the day there’s no universal “better” — there’s only “better for your specific pain”. Drop us a line at info@photo-detector.com oder drücken Sie die Kontaktseite and tell us what you’re trying to measure, what your power budget looks like, distance, environment… we’ll tell you straight which way to go and quote you something that actually works.
Or just browse around Bienen-Photon — we’ve got application notes, spectrum plots, and a bunch of other geeky stuff that might save you a few nights of worrying.
Hope this helped clear the fog a bit. Happy to chat specifics anytime.
