Safety Light Curtain vs Laser Scanner: Which Machine Guarding Solution Is Right for You?
When designing a comprehensive machine guarding system, one of the most common questions safety engineers face is: should I use a safety light curtain or a laser scanner? The answer depends on your specific application requirements, risk assessment outcomes, and operational context. This guide provides a detailed comparison to help you make the right decision.
How Each Technology Works
Safety Light Curtain
A safety light curtain creates a plane of infrared beams between a transmitter and receiver. The transmitter emits pulsed infrared light across an array of beams, and the receiver monitors them. Any opaque object that interrupts one or more beams triggers an immediate safety stop. Response time is typically 5-15 milliseconds.
Safety Laser Scanner
A safety laser scanner uses a rotating infrared laser scanning a 270-degree field of view, measuring time-of-flight to determine distances. Configurable with multiple zones: warning zone triggers slowdown; safety zone triggers immediate stop. Response time is typically 60-134 milliseconds.
Safety Level Ceiling Rule
This is the most critical factor. A Type 3 / SIL2 laser scanner cannot replace a Type 4 / SIL3 safety light curtain for high-risk applications.
| Characteristic | Safety Light Curtain | Safety Laser Scanner |
|---|---|---|
| IEC 61496 Type | Type 2 or Type 4 | Type 3 |
| Maximum SIL | SIL 3 | SIL 2 |
| Maximum PL | PLe (Cat 4) | PLd (Cat 3) |
| Finger detection (14mm) | Yes | No |
| Hand detection (30mm) | Yes | No (min ~70mm) |
| Point-of-operation guarding | Yes | No |
Example: In a press brake where hands enter the die area, only a Type 4 safety light curtain with 14mm resolution works. No laser scanner can meet this requirement.
Use Case Comparison
Press Brakes
Light Curtain — fast response, finger detection, point guarding
Robot Work Cells
Laser Scanner + Light Curtain — hybrid is best practice
AGV/AMR
Laser Scanner — mobile platform, 270-degree area scanning
Conveyors
Light Curtain with Muting — product passage with operator safety
Large Irregular Areas
Laser Scanner — configurable protection fields
Assembly Lines
Light Curtain — fixed point, fast response, cost-effective
Cost and Complexity Analysis
| Cost Factor | Safety Light Curtain | Safety Laser Scanner |
|---|---|---|
| Equipment purchase | Lower ($150-$3000) | Higher ($800-$5000) |
| Installation | Moderate | Higher (area programming needed) |
| Maintenance | Low | Moderate (environment sensitivity) |
| False trigger risk | Low | Higher (dust, reflections) |
| Reconfiguration | Mechanical realignment | Software-based, flexible |
Hybrid Solutions
In many modern factories, the optimal approach combines both technologies. A safety light curtain protects the point-of-operation while a laser scanning radar monitors the surrounding area. DADISICK manufactures both product lines, ensuring seamless integration.
Safety Distance Comparison
ISO 13855 safety distance calculation differs significantly between the two devices. For a 14mm light curtain with 100ms total stopping time: S = 2,000 x 0.100 + 0 = 200mm. For a laser scanner with 80ms response plus 100ms machine stop: S must factor in scanning plane height and typically results in 1,000-1,500mm. Light curtains mount closer to the hazard, saving valuable floor space.
Four-Question Decision Framework
- Need finger/hand detection at a fixed point? → Safety Light Curtain
- Irregular or mobile protection area? → Safety Laser Scanner
- Installed on moving platform (AGV/AMR)? → Safety Laser Scanner
- Need both area monitoring AND point protection? → Hybrid (both)
DADISICK Solutions for Both
DADISICK offers a comprehensive range of safety light curtains (Type 4, multiple resolutions) and laser scanning radars (270-degree scanning), allowing single-supplier sourcing for complete safety solutions.
