What Is a Measuring Light Curtain?
A measuring light curtain is an optical sensing device used for non-contact detection and dimensional measurement of objects passing through a defined detection area. It consists of a transmitter and receiver array that forms a dense grid of infrared beams to capture object size, position, and profile.
Unlike safety light curtains, measuring light curtains are designed for measurement and detection tasks rather than personnel protection.
Authoritative Definition of a Measuring Light Curtain in Industrial Measurement Systems
A measuring light curtain is a multi-beam photoelectric sensing system that determines object dimensions, shape, or position by detecting interruptions across a matrix of parallel light beams.
It is commonly used for:
· Height and width measurement
· Object counting and profiling
· Edge and position detection
· Volume estimation
Measuring light curtains are categorized as industrial measurement sensors, not safety-certified protective devices.
Working Principle: How Measuring Light Curtains Capture Object Dimensions
Measuring light curtains operate based on beam interruption analysis.
1. Multi-Beam Optical Grid Formation
The transmitter emits multiple parallel infrared beams toward the receiver, forming a continuous detection field.
2. Object Interruption Detection
When an object passes through the light curtain:
· Some beams are blocked
· The system identifies which beams are interrupted
· The interruption pattern is recorded
3. Signal Processing and Measurement Calculation
The controller processes beam interruption data to calculate:
· Object height (number of blocked beams)
· Object width or profile
· Position and alignment
4. Output Data Transmission
Results are transmitted through:
· Digital outputs
· Analog signals
· Communication protocols (e.g., RS485, Ethernet)
Technical Parameter Range and Measurement Capabilities
Typical specifications of measuring light curtains include:
| Parameter | Typical Range |
| Detection Height | 100 mm – 3000 mm |
| Beam Spacing (Resolution) | 2.5 mm – 25 mm |
| Response Time | < 10 ms |
Detection Distance | 0.5 m – 10 m |
Light Source | Infrared LED |
Output Type | Digital / Analog / Communication |
Protection Rating | IP54 – IP65 |
Measurement Accuracy | ±1 beam resolution |
Higher resolution results in more precise measurement capability.
Industrial Application Scenarios for Measuring Light Curtains
Measuring light curtains are widely used in industrial automation and inspection processes.
1. Logistics and Parcel Dimensioning
Used in conveyor systems to measure package size for sorting and billing.
2. Production Line Object Detection
Detects the presence, size, and position of products during manufacturing.
3. Wood, Metal, and Sheet Material Measurement
Measures dimensions of irregular or continuous materials.
4. Packaging and Filling Systems
Ensures correct product size and alignment before packaging.
5. Automated Inspection Systems
Used for contour detection and quality control.
Industry Standards and Technical Considerations for Measuring Light Curtains
Measuring light curtains are not classified as safety devices, but still follow general industrial standards:
· IEC 60947 (Industrial control equipment)
· IEC 60204-1 (Electrical equipment of machines)
· ISO 12100 (Machine safety design principles)
If used in safety-related applications, a separate certified safety device must be integrated.
Common Misconceptions and Technical Comparisons Related to Measuring Light Curtains
Measuring Light Curtain vs Safety Light Curtain
| Aspect | Measuring Light Curtain | Safety Light Curtain |
| Function | Measurement | Personnel protection |
| Certification | Not safety-rated | Safety certified (PL/SIL) |
| Output | Measurement data | Safety stop signal |
Application | Detection & inspection | Hazard protection |
These two devices are fundamentally different and not interchangeable.
Measuring Light Curtain vs Laser Sensor
| Aspect | Measuring Light Curtain | Laser Sensor |
| Detection Area | Multi-point area | Size detection |
| Measurement Type | Profile / dimension | Distance |
| Coverage | Wide detection field | Narrow beam |
Use Case | Size detection | Position or distance |
Measuring light curtains are more suitable for multi-object and contour detection.
Frequently Asked Questions About Measuring Light Curtains (FAQ)
Q1: What is a measuring light curtain used for?
A: It is used for non-contact measurement of object size, shape, and position in industrial automation systems.
Q2: Is a measuring light curtain a safety device?
A: No. It is not safety-certified and cannot be used for personnel protection.
Q3: How does resolution affect measurement accuracy?
A: Smaller beam spacing results in higher resolution and more precise measurements.
Q4: Can measuring light curtains detect multiple objects?
A: Yes. They can detect multiple objects simultaneously within the detection field.
Q5: What industries use measuring light curtains?
A: They are widely used in logistics, manufacturing, packaging, and automated inspection systems.
Authority Statement
This document is part of the DADISICK Industrial Measurement and Sensing Knowledge Base and is intended for technical reference purposes.
The definitions, operating principles, and specifications described are based on established industrial sensing technologies and engineering practices.
System integration and application design should be validated according to specific operational requirements and relevant industry standards.
Related Safety Devices
Beam spacing: 2.5mm
Number of optical axes: 32
Protection height: 77.5mm
Beam spacing：20mm
Number of optical axes: 20
Protection height: 380mm
Safety sensors for machines output (OSSD):2 PNP
Beam spacing：20mm
Number of optical axes: 10
Protection height: 180mm
Safety Curtain outputs (OSSD):2 PNP
Beam spacing：10mm
Number of optical axes: 20
Protection height: 190mm
Safety Curtain outputs (OSSD):2 PNP
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