The LGauge - High-Precision Confocal Thickness Measurement

The LGauge is engineered for simplicity and high-speed integration. The system features a decentralized architecture where intelligent sensors are connected to a central controller via a single, high-bandwidth digital link. The sensors utilize Power over Ethernet (PoE) for streamlined cabling, while the controller—a high-performance PAC (Programmable Automation Controller)—handles signal processing, I/O management, and provides a web-based operator interface.

Any PC, tablet, or device with an internet browser can connect to the system to act as an HMI, independent of the operating system. The controller also supports socket server applications and industrial communication protocols for seamless integration.

The LGauge typically consists of three primary components:

• Controller (Core): A PAC-based unit housed in a compact industrial cabinet. It manages data acquisition, processes sensor signals, and runs the operator interface.
• Sensor Head: A compact, IP-rated optical unit containing the confocal lens and emitter. It is connected to the controller via a single hybrid cable (fiber optic and power).
• Mounting Frame: A modular frame system designed for integration into production lines, available in static (single-point) or scanning (profile) configurations.

Thanks to its support for multiple industrial protocols (Ethernet/IP, Profinet, OPC-UA, and analog/digital I/O), the LGauge integrates easily into new or existing automation systems. It can share commands and thickness data in real-time with PLCs, SCADA systems, and quality management platforms.

Applications, Materials, and Measuring Range
The LGauge is the ideal solution for non-contact thickness measurement on a wide range of materials where traditional sensors fail. Its confocal technology ensures stable performance on:

• Transparent materials: Glass, films, coatings, adhesives, and plastics.
• Reflective surfaces: Polished metals, wafers, and mirrors.
• Diffuse and textured surfaces: Ceramics, composites, and painted layers.
• High-slope surfaces: Curved or uneven parts.

The sensor heads are designed for industrial environments, combining optical precision with robust construction. Each sensor contains a chromatic confocal lens that uses wavelength dispersion to achieve sub-micron accuracy. Unlike conventional sensors, the measurement is independent of surface reflectivity, angle, or material color.

• Chromatic Confocal Lens: Emits white light dispersed into a spectrum; a specific wavelength is focused on the target surface.
• Spectrometer Receiver: Analyzes the reflected wavelength to determine distance with nanometer-level resolution.
• Digital Interface: Integrated electronics with PoE and industrial protocol support.
• Protection: IP67-rated housings resistant to dust, moisture, and mild chemical exposure.

Requirements

Parameter    Specification
Operating Temperature    +5 °C to +50 °C
Storage Temperature    -10 °C to +60 °C
Humidity (Operating)    10% to 90% (non-condensing)
Protection Class    IP67 (sensor head)
Shock Resistance    10G (11ms)

Performances

The LGauge delivers precision measurement capabilities suitable for the most demanding quality control applications.

Response Time    from 0.5 ms    Adjustable based on averaging
Resolution    0.1 µm   Dependent on measurement range
Accuracy    +/- 0.02% of range    Static conditions
Linearity    < +/- 0.01%    Over full measurement range
Repeatability    < 0.1 µm    Under stable environmental conditions

The system is designed to comply with international standards for industrial measurement equipment, including:

• IEC 60825-1 (Laser Safety, where applicable)
• EN 61326-1 (EMC requirements for electrical equipment)
• ISO 25178 (Areal surface texture measurement)
• ISO 17025 (Calibration traceability)

Calibration is performed using certified reference standards ensuring measurement accuracy and consistency.

• Strengths of the LGauge System
  Versatile Material Compatibility: Measures transparent, reflective, and opaque surfaces with equal precision without requiring surface preparation.
• Multi-Layer Measurement: Capable of measuring up to five layers simultaneously (e.g., coating + substrate + air gap).
• High Angular Tolerance: Maintains accuracy even on steep slopes or curved surfaces where laser triangulation fails.
• Digital Architecture: Proprietary sensors with PoE connectivity minimize cabling and simplify installation.
• Open Protocols: Cross-platform web-based HMI and standard industrial communication protocols for easy integration.
• High-Speed Processing: Real-time data output with response times suitable for closed-loop process control.
• Compact and Robust: IP67-rated sensors designed for integration into tight spaces and harsh industrial environments.
• Traceable Calibration: System includes certified reference standards for routine verification and calibration.