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. 


No Special Reflective Tape Required
Operates in remote and/or hostile environments
Gets into inaccessible spaces
Right angle attachments available
Custom Cable lengths up to 300 Meters
Displays in units of RPM, RPS, or Pulses per Second
TTL Compatible Output, Rep rate to 40 KHz


Ordering Information
LT-880 Fiber Optic Laser Tachometer

5 Meter Cable w/Reflective Sensor Head


5 Meter Cable w/Transmissive Sensor Head

RAA-LT880 Right Angle adapter Head for LT-880

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 u m core, Transmitter - 62.5 um core

Standard Connector Type

ST Type

Batteries Supplied

Four AA NimH, 2700 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 - 50 C, - 40 - 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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