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Proton Products SL mini and SLR mini Series Speed and Length Gauges Instruction Manual - issue 1s
I
NTRODUCTION
The Proton Products SL mini and SLR mini series of laser speed and length gauges provide highly-
accurate, non-contact speed and length measurement.
SL mini series gauges offer speed and length measurement for unidirectional production lines.
SLR mini series gauges offer speed and length measurement for bidirectional production lines. The
gauge senses the direction of motion and will automatically increment or decrement the length
accordingly. SLR mini gauges are thus suitable for production lines that undergo direction reversals or
stationary (zero speed) periods.
Compared to traditional contact wheel encoders, SL mini / SLR mini non-contact speed and length
gauges offer the following advantages:
Capable of measurement at much higher speeds and accelerations
No slippage
Greater accuracy
No wear or damage to the measured object
Solid state design results in higher reliability and MTBF
RS-232 and Ethernet communication interfaces are installed as standard for straightforward
connection to computers or PLCs. One optional industrial standard communication interface
(PROFIBUS, EtherNet/IP or DeviceNET; replaces the standard Ethernet interface) may also be
installed in the gauge.
User configurable digital inputs are provided as standard to reset gauge measurements and trigger
printing. User configurable digital outputs are provided as standard to signal gauge status and preset
length reached.
P
RINCIPLE OF
O
PERATION
SL mini series unidirectional speed and length gauges illuminate the measured surface with a
precisely pitched interference pattern created by the intersection of two laser beams. The alternating
bright and dark interference fringes modulate the light scattered by the object with a frequency
proportional to the object speed. This scattered light is detected by a photodiode and the electrical
signal digitally processed to determine the frequency and hence the speed. Object length is then
calculated by integrating the speed measurement over time.
SLR mini series bidirectional speed and length gauges extend this principle by using a high-frequency
Bragg cell modulator to illuminate the measured surface with a scanning interference pattern, which
generates an oscillating light signal even when the object is stationary. Direction of motion is
determined by whether the scattered light frequency is higher or lower than the stationary frequency.
