Lumens, watts and what reaches the wall
Three output figures get mixed up constantly: lumens describe what the lamp produces, lux describes what arrives on the surface, and watts describe what you pay for. A laser line safety drawing 15–60 W might deliver 3,000 lumens, but the lux at the wall depends entirely on how wide you spread it. The same lamp projecting a 1 m image is nine times brighter than the same lamp projecting a 3 m image.
Throw distance and image size
Throw distance without image width is meaningless, and plenty of sheets quote only one. A laser line safety 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.
| Throw | Typical image width | Practical note |
|---|---|---|
| Short, around 5 m | 0.5 – 1.5 m | Bright and easy — most indoor work |
| Mid, around 30 m | 1.5 – 3 m | Where lens quality starts to matter |
| Long, beyond 30 m | 3 m and up | Contrast fails before reach does |
The optical spec most sheets leave out
Two numbers govern the image: gobo image area and the resolution the lens can carry. Glass gobos can be engraved far finer than any laser line safety lens in this class will resolve, so the practical limit is optical. That is worth knowing before you pay for engraving detail nobody will see from 10 m away.
IP rating and electrical data
Ratings age. A laser line safety that left the factory rated IP54 can lose that rating the first time somebody opens it to change a gobo and reseats the gasket badly. Look for a design where routine access does not mean breaking the environmental seal, or accept that the rating applies to the unit as delivered, not as maintained.
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 line safety can be opened on site without voiding the rating, and how quickly artwork can be re-cut if a branch changes its logo.
