1

Sensing with Light and Fibers - EO & LasMetr Lab

Professor Dr. Friedemann Mohr

HS Pforzheim University, Electrooptics & Laser Metrology LabBrno, 09.11.2010

Sensing with Light and Optical Fibers

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 2

Overview

1. The fiber gyroscope -a rotation rate sensor for use in avionics: Suppression of unwanted cross-sensitivity from elastooptical interactions

2. Embedded fiber-optic sensingwith fiber Bragg gratings and its use in civil engineering,

3. Polarimetrywith microstructured polarizers, a concept enabling real-time measurement of internal stress in optically transparent media

2

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 3

Part 1 - The fiber gyroscope -

Suppression of unwanted cross-sensitivity from thermal and elastooptical interactions

Project „EMFASE“ - Industrial Partner: SAGEM Navigation

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 4

Only for reference:

The part on

„The Fibre Gyroscope“ project

is cancelled for BIPOMIP presentation

3

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 5

Part 2 - Embedded fiber-optic sensing –

Fiber Bragg Gratings (FBGs) and their use for Structural Health Monitoring (SHM) in civil engineering

Project „FOSBA“ - Industrial Partner: Bilfinger Berger

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 6

Only for reference:

The part on the

„Embedded Fibre Optic Sensing“ project

is cancelled for BIPOMIP presentation

4

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 7

Part 3 - Polarimetry with microstructured polarizers

A Sensor Concept enabling Real-Time Measurement of Internal Stress in Optically Transparent Media

Project „BIPOMIP“ -Industrial Partners: ilis Erlangen, CODIXX Magdeburg

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 8

Aim of Polarimetric Measurement and

Basic Arrangement for Measuring Birefringence

Aim:

� Determine optical birefringence in

technical glass-products bypolarization analysis.

� Derive internal stress therefrom byapplying elastooptical equations.

� Improve quality of glass products in manufacturing process

� Reduce energy consumption bybetter process control

5

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 9

Industrial Arrangement of a Polarimeter

(isis Erlangen)

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 10

Concepts for Spatially-Resolved Polarization Analysis

6

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 11

Basic Arrangement for Measuring Birefringence

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 12

First, the source is imaged on a spatial filter (a pinhole). A collimating lens follows. The collimated beam is needed in order to assure one-to-one imaging between a point in the model plane and a point in the detector plane. After the collimator a linear polarizer (polarizer) follows. Next, the investigated model is placed. Then another linear polarizer (analyzer) follows. The polarizer and analyzer are

crossed (dark field setup). Finally, the model plane is imaged on a CCD sensor

The basic photo-elastic bench (linear polariscope).

7

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 13

Strain discs patterns for different loads (load A<B<...<F)

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 14

Dependency of the strain disc pattern (load E) on the

angle between polarizer and applied force (stress).

(Mixing of isoclinics and isochromatics.)

8

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 15

Manufacturing of Micro Polarizers

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 16

Adjustment of Micro Polarizers and CCD Array

9

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 17

Good Adjustment of Micro Polarizers and CCD Array

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 18

Bad Adjustment of Micro Polarizers and CCD Array

10

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 19

Micro Polarizers as Diffractive Optical Elements 1

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 20

Micro Polarizers

as

Diffractive

Optical

Elements 2

11

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 21

Micro Polarizers as Diffractive Optical Elements 3

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 22

Scattering due to the Particle Structure

12

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 23

The Real-Time

Polarimeter 1

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 24

The Real-Time Polarimeter 2

Same as a colour versionPolarization image as taken by camera

Calculated retardationafter image processing

13

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 25

Further Steps

� Noise Optimization

� Hardware implementation of some part of the image processing

� Goal: Measurement speed of 20 measurements in one second

09.11.10 Sensing with Light and Fibers - EO & LasMetr Lab 26

Summary

1. The fiber gyroscope -a rotation rate sensor for use in avionics: Suppression of unwanted cross-sensitivity from elastooptical interactions

2. Embedded fiber-optic sensingwith fiber Bragg gratings and its use in civil engineering,

3. Polarimetrywith microstructured polarizers, a concept enabling real-time measurement of internal stress in optically transparent media