Read the sheet in the order it is installed
Nothing on a spec sheet is dishonest; plenty of it is irrelevant. A laser diode lifespan sheet will quote lumen output, power draw and beam angle, but what you need is image width at your throw distance and contrast against the light already on the surface. Those require two more numbers the sheet usually does not give you, which is why they are worth asking for.
Output numbers, ranked by how much they lie
Wattage tells you the running cost, not the result. Two laser diode lifespan models at the same wattage can differ by 30% at the wall because of lens efficiency and LED binning. What you actually care about is contrast: the image needs to be meaningfully brighter than the surface it lands on, and that is a lux comparison, not a lumen one.
| Figure | What it measures | How much to trust it |
|---|---|---|
| Lumens | Total light leaving the lamp | Rough sorting tool — ignores lens and gobo losses |
| Lux at the wall | Light arriving on the surface | The number that matters, rarely quoted |
| Watts | Power drawn from the supply | Tells you running cost, not brightness |
Throw distance and image size
Throw distance without image width is meaningless, and plenty of sheets quote only one. A laser diode lifespan that throws 30 m might give you a 1 m logo at that distance or a 6 m one, depending on the lens — a difference that decides whether the install works. Always ask for the pair: distance and the resulting image size.
IP rating and electrical data
The electrical block is boring and expensive to get wrong. Confirm the input voltage range matches your supply, check whether the laser diode lifespan ships with a local plug, and look for CE, RoHS and FCC marks if the install is commercial. A unit that is electrically fine but uncertified will not pass a site inspection in most markets.
What a good supplier answers without hesitating
Ask for measured figures rather than calculated ones: image lux at a stated distance, image width at your throw, and the gobo image area. Then ask what happens when the unit needs servicing — whether the laser diode lifespan can be opened on site without voiding the rating, and how quickly artwork can be re-cut if a branch changes its logo.
