Web and coil deviation correction
Tracks the edge of a moving web or strip and feeds a steering frame so the material stays on centre.
Measuring · Dimensional measurement
LC Series Measuring Light Curtain
A measuring light curtain with 2 mm minimum accuracy and up to 500 beams, converting the interrupted beam count into a dimension, an edge position or a count
Model LC Series · Brand LE Raun · Category: Measuring & Vehicle Separation Light Curtains
Min. accuracy2 mm
Beam quantity4–500 beams
Response time<90 µs
OutputNPN / PNP / RS232 / RS485 / Relay
Overview
A measuring light curtain is a light curtain read as a ruler. With an optical axis pitch down to 2 mm and up to 500 beams, the receiver knows exactly which beams are interrupted, and the controller converts that pattern into a width, an edge position or an object count.The LC Series runs on 24 V DC with wired synchronisation and a response time under 90 µs — fast enough to measure product moving on a line rather than only static parts. Outputs include NPN/PNP switching, and RS232 or RS485 for sending the measured value to a PLC or PC.
Application scenarios
Spray and coating width
Measures the width of a sprayed band and flags drift in the nozzle pattern.
Dimension measurement
Checks width, height or profile of a part as it passes the curtain.
Workpiece counting and sorting
Counts parts on a conveyor and triggers a diverter by size.
Precision offset detection
Detects small positional offsets on battery electrodes, film and sheet.
Speed and length detection
Times consecutive interruptions to derive line speed and cut length.
Industries
- Lithium battery
- Packaging
- Printing and converting
- Textiles
- Automotive parts
Technical specifications
| Model | LC Series |
|---|---|
| Cross-section | 30 × 30 mm / 35 × 40 mm |
| Beam quantity | 4–500 beams (standard) |
| Minimum accuracy | 2 mm |
| Sensing distance | 0.1–2 m / 0.1–3 m / 0.1–5 m / 0.1–10 m / 0.1–15 m / 0.1–20 m |
| Optical axis pitch | 2 / 2.5 / 5 / 7.5 / 10 / 15 / 20 / 30 / 40 / 60 mm |
| Operating voltage | DC 24 V ±10% |
| Signal output | NPN / PNP / RS232 / RS485 / Relay (optional) |
| Synchronization type | Wired synchronization |
| Response time | <90 µs |
| Protection level | IP65 |
| Light curtain form | Through-beam type |
| Product application | Deviation correction detection / spraying detection / dimension measurement / coordinate positioning / workpiece counting / material sorting / speed detection / precision offset detection |
| Minimum resolution | 1 mm (beam pitch) |
| Beam count | 128 – 1000+ beams per axis |
| Fastest response | 290 µs per axis |
| Output selection | Ordered as interface option; both digital and analogue may be fitted |
| Mounting | Two axes can be crossed for X-Y dimensions |
Dimensions
| Item | Value |
|---|---|
| Effective height | beam count × pitch − pitch |
| Overall length | effective height plus the two end caps |
| Mounting | Rear T-slot; the two axes can be crossed for an X-Y measurement |
The section is fixed by the series and the length is built to the beam count you order, so confirm the overall length on the drawing before the frame is welded — the end caps add to the effective height.
Wiring & output
| Interface | Use |
|---|---|
| RS232 | Point-to-point link for commissioning and for older controllers |
| Analogue 4–20 mA / 0–5 V / 0–10 V | Proportional to the measured width or edge position |
| Relay / switch output | Threshold decision — part present, width out of tolerance |
| Trigger input | Starts a measurement window from a photo-eye or encoder pulse |
How to specify
- 01
Fix the measuring task
Edge position, width, height, hole pitch or count — each needs a different mounting. Two crossed axes give X-Y dimensions; a single axis gives width or edge position only.
- 02
Choose the beam pitch
1 mm for small parts and fine edges, 2 mm for cartons and profiles, 10 mm for large objects where only presence or coarse width matters. The pitch fixes the smallest step you can see.
- 03
Choose the interface
RS485 / Modbus when the controller already speaks Modbus and several curtains share the bus; analogue when the PLC has only an analogue card; relay when the result is a simple go / no-go.
- 04
Size the curtain to the object
The protective height must exceed the largest dimension plus the expected position scatter — a carton that sits 30 mm off centre needs 60 mm of extra field.
Why this series
2 mm optical pitch
Resolves small features and edge positions that a guarding curtain cannot see.
Up to 500 beams
Measures across wide webs without losing resolution.
Sub-100 µs response
Fast enough for on-the-fly measurement and closed-loop correction.
Questions
How is this different from a safety light curtain?
A safety curtain is a switching device for personnel protection. The measuring curtain is an analogue measuring device: it resolves individual beams to report a dimension, and its 2 mm pitch and RS485 output are aimed at the controller, not the safety relay.
What accuracy can I expect?
Minimum accuracy is 2 mm with the finest optical pitch. The achievable accuracy on a real part also depends on edge condition, mounting rigidity and the pitch you select.
Which output should I specify?
NPN or PNP for simple go/no-go decisions, RS232 or RS485 when the measured value has to be sent to a PLC or PC, and relay where volt-free contacts are required.
Can the curtain measure a moving object?
Yes — the 290 µs scan is faster than any conveyor. The limit is the trigger: start the measurement from an encoder pulse or a photo-eye so the controller knows which part the beam map belongs to.
Need a quotation for LC Series?
Send your application details or the guard opening dimensions and we will specify the right model and configuration for your machine.