Name: os3500 Embeddable Optical Strain Sensor for Concrete Structures
Brand: Luna
SKU: os3500

Overview

The os3500 Embeddable Strain Sensor measures average strain over the length of the gage and provides integrated temperature compensation. It is based on fiber Bragg grating (FBG) technology and is intended exclusively for embedding in concrete structures. Disk ends form a solid bond with the surrounding concrete or grout.

The sensor has a stainless steel body, ruggedized cables and optional connector protection fittings for use in harsh environments. Two FBGs are protected inside the body: one measures strain and the other provides integrated temperature compensation. No epoxies hold the fiber to the carrier, which supports long-term stability by design.

According to the manufacturer, side-by-side comparisons with vibrating-wire and foil strain gages show the os3500 to be equally sensitive and accurate while providing 100 times more fatigue life. The gage is qualified for use in harsh environments.

The sensor can be used alone or in series as part of an FBG sensor array. Its double-ended design allows many sensors to be multiplexed on one fiber, and it is used with Luna HYPERION interrogators for monitoring applications.

Key Features

Ruggedized sensor package, qualified to the same rigorous standards applied to electronic gages
Integrated temperature compensation FBG sensor
Connector protection fittings available for harsh environments
Double-ended design supports multiplexing of many sensors on one fiber
Patented micro opto-mechanical technology
Fast, simple, repeatable installation
Disk ends bond to surrounding concrete or grout
No epoxies holding the fiber to the carrier

Specifications

Performance Properties

Strain sensitivity	~ 1.2 pm/με Actual gage factor provided with gage
Temperature sensitivity	23.8 pm/°C Actual gage factor provided with gage
Temperature compensation	Integrated into each package
Gage length	110 mm
Operating temperature range	-40 to 80 °C
Strain limits	± 2,500 με
Water resistance	Suitable for wet, high humidity environments (IP67)
Fatigue life	> 1x10^8 cycles @ +/- 2,000 ue

Physical Properties

Dimensions	See diagram Dimensions in mm given in the data sheet diagram
Weight	98 g
Carrier material	Stainless Steel/Polyolefin construction
Cable type / length	6 mm/3 mm ruggedized cable/1 m (+/- 10 cm), each end
Cable bend radius	≥17 mm
Fastening methods	Embeddable

Optical Properties

Peak reflectivity (Rmax)	> 70%
FWHM (- 3 dB point)	0.25 nm (± .05 nm)
Isolation	> 15 dB @ ± 0.4 nm around center wavelength

Ordering Information

Part number format	os3500-tttt/ssss-1xx-1yy tttt/ssss = strain/temperature wavelengths; 1xx = cable 1 length & connector; 1yy = cable 2 length & connector
Strain/temp wavelengths (+/- 1nm), standard	1462/1466, 1472/1476, 1482/1486, 1492/1496, 1502/1506, 1512/1516, 1522/1526, 1532/1536, 1542/1546, 1552/1556, 1562/1566, 1572/1576, 1582/1588, 1592/1596, 1602/1606, 1612/1616 Values in nm
Cable length	1 m Standard, Cable Length Code 1 in positions 1xx / 1yy
Ordering example	o3500-1512/1516-1FC-1FC Printed as shown in the data sheet

Specifications are taken from the manufacturer's documentation. See the datasheet for complete and current values.

Options & Accessories

Option	Description
UT	Unterminated — Termination type for cable 1 (1xx) or cable 2 (1yy)
FC	FC/APC Connector — Termination type for cable 1 (1xx) or cable 2 (1yy)
PF	Universal IP67 Connector with Protection Fitting — Accessory