Panasonic HL-G108A-RS-J Laser Displacement Sensor

Technical Overview

High-function specular reflection laser sensor with a 2.5 µm resolution, ±10 mm range, RS-422/RS-485 serial communication, and an IP67-rated compact enclosure.

Key Features

Specular reflection geometry optimized for highly reflective mirror-like surfaces, glass, and wafers
High-functionality model featuring selectable RS-422/RS-485 serial communications
Class 1 red semiconductor laser light source safe for standard operating environments
Built-in 5.5-digit, 7-segment red LED digital display for real-time monitoring and setup
Three user-selectable NPN/PNP open-collector transistor judgment/alarm outputs
Simultaneous current (4-20mA) and voltage (0-10V) analog outputs
Fast sampling rates configurable from 200 μs to 2 ms
IP67 dust- and water-proof PBT protective enclosure with metal-reinforced mounting holes

Technical Specification Matrix

Parameter	Value
Measurement Method	Specular reflection
Measurement Center Distance	82.9 mm
Measurement Range	±10 mm
Resolution	2.5 μm
Linearity	±0.2 % F.S.
Temperature Characteristics	±0.08 % F.S. / °C
Light Source	Red semiconductor laser, Class 1
Max. Output Power	0.39 mW
Peak Emission Wavelength	655 nm
Beam Diameter	0.2 x 0.2 mm (at measurement center distance)
Receiving Element	CMOS image sensor
Supply Voltage	24 V DC ±10% (including ripple)
Current Consumption	100 mA or less
Sampling Rate	200 μs / 500 μs / 1 ms / 2 ms
Analog Output (Voltage)	0 to +10.5 V (normal), 11 V (alarm)
Analog Output (Current)	3.2 to 20.8 mA (normal), 21.6 mA (alarm)
Control Outputs	3 outputs (OUT 1, OUT 2, OUT 3), NPN/PNP open-collector selectable
Communication Interface	RS-422 / RS-485 (selectable)
IP Rating	IP67
Operating Temperature	-10 to +45 °C
Physical Weight (kg)	0.11
Dimensions L x W x H (cm)	5.7 x 2.04 x 6

Industrial Applications

1. Silicon Wafer Tilt and Height Positioning

Directing a Class 1 laser onto highly reflective silicon wafers to determine exact height and tilt before robotic wafer-handling processes.

Problem Solved

Silicon wafers used in semiconductor manufacturing have mirror-like finishes that cause standard diffuse sensors to experience massive light dispersion. The specular reflection optical layout of the HL-G108A-RS-J captures direct specularly reflected light from mirror surfaces, enabling a precise 2.5 µm resolution height profile without harming the surface.

silicon waferspecular reflectionsemiconductor processingZ-axis positioningClass 1 laser

2. Glass Panel Thickness and Flatness Verification

Continuous non-contact measurement of flat panel display (FPD) glass substrates on high-speed conveyor lines.

Problem Solved

Transparent glass panel substrates reflect light poorly when using diffuse laser sensors, as light passes straight through. This sensor's specialized specular alignment captures reflection off the front polished surface, leveraging the ±10 mm range to detect thickness variations, warp, or sag in the glass substrate during automated transport.

FPD glass substrateglass thicknessflatness verificationspecular alignmentdisplacement sensor

3. High-Speed HDD Platter Runout Monitoring

Real-time verification of mirror-finished hard disk drive (HDD) platters during spin testing to evaluate axial runout and rotational eccentricity.

Problem Solved

Extremely reflective HDD platters rotate at thousands of RPM, requiring high-frequency feedback and zero toleration for reflection scattering. A 200 μs sampling cycle paired with RS-485 serial communication allows this sensor to feed rapid distance measurements to a host controller, flagging minimal axial wobbles in real-time.

axial runoutHDD plattereccentricityRS-485 communication200 μs sampling