Terahertz Technologies Inc.Terahertz Technologies Inc.
(888) U.S.-OTDRS
LT-880 Laser Tachometer


The LT-880 Fiber Optic Laser Tachometer is a non-contact instrument designed to measure rates of rotation by sensing the presence of absence of a reflective surface in its optical beam. These are typically provided by affixing an easily made black and white encoder to the surface of the rotating component. A TTL signal is asserted whenever a reflective surface is sensed. The output signal may be read directly from the display or used in conjunction with a spectrum analyzer to sense linear translation, RPM, and angular vibrations. A five meter fiber optic cable enables the optical sensor to be placed in hazardous environments and/or inaccessible spaces where a conventional unit cannot be used. The LT-880 adds the additional flexibility of a multi-functional readout. 



Encoders may be made easily with a laser printer and any drawing or CAD program.





Remote Sensing of RPM and Angular Vibration

No Special Reflective Tape Required

Large 5 Digit LED Display 

Sensing rates to 40 000 PPS

Ni-mH Powered with Fast Charger

Measures RPM, RPS, PPS

Entry of number of encoder sectors



Ordering Information


Fiber Optic Laser Tachometer (Includes 5 Meter Cable with Reflective Sensor Head)


Fiber Optic Laser Tachometer (Includes 10 Meter Cable with Reflective Sensor Head)


Fiber Optic Laser Tachometer (Includes 5 Meter Cable with Transmissive Sensor Head)


5 Meter Cable w/Refl ective Sensor Head for use with LT 880


5 Meter Cable w/Transmissive Sensor Head for use with LT 880


Right Angle Adapter for use with LT-880 Reflective Optical Head


LT-880 Laser Tachometer Specifications

Units of Measurement

Revolutions per Second, Revolutions per Minute, Pulses per Second

Measurement Update Rate

Twice per Second

Readout Uncertainty

± .02 % of Reading, ± .1 LSD

Maximum Measurement Rate

40 000 PPS

Range from Sensor to Target

12 to 125 mm (using white copier paper)

Laser Wavelength

650 nm ± .10 nm

Laser Output Power

< 2 milliwatts

Laser Spot Size

< 1.9 mm @ 13 mm range

Laser Beam Divergence

< 13 milliradians


Six Digit LCD, 0.375 height, Six LED annunciators

Frequency Output Port

TTL pulse for each reflective sector sensed, (0 to 5 volts)

Output Impedance

100 Ohms

Standard Fiber Optic Cable Length

5 meters

Standard Fiber Types

Receiver - 400 um core, Transmitter - 62.5 um core

Standard Connector Type

ST Type

Batteries Supplied

Four AA NimH, ≥ 2500 mAH

Charger Power Requirements

95 - 260 VAC, 50-60 Hz Universal, < 10 VA

Mains Connectors Supplied

North American, Great Britain, Continental Europe, Australian

Charging Time

Approximately two hours

Dimensions (Controller)

200 mm L x 98 mm W x 38 mm D

Dimensions (Sensor)

40 mm L x 13 mm Diameter, 1/2 by 20 Thread, Jam Nuts Included

Operating Temperature, Electronics, Sensor Head

0 to 50 C, -40 to 120 C


0.46 Kg

Accessories Provided

Carrying Case, Batteries, Power Supply/Charger, Operating Manual

Standard Warranty

Two years, Components and Workmanship, 30 Day Satisfaction Guarantee

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