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Laser Fibre Gyroscope

 
Topics:
Sagnac Effect
Fibre Ring Laser
Ring Laser Modes
Unidirectional Modes
Interference
Fringe Detection
Mode Lock-In
High Precision Angle Measurement
 
   

 


Principle of operation


Nowadays Airbus and Boeing air-planes are equipped with laser gyros for navigation. Beside their high precision they have shown reliability, long term stability as well as a long lifetime.

Within this experimental set-up the basics of the laser gyro are explained and practically studied at the system, which allows full access to all components. The experimental laser gyroscope (gyro) consists of a rugged turntable on which the fibre ring laser is mounted. By means of a motorised rotational stage the angular motion of the turntable is performed. The ring laser consist of an Erbium doped Fibre (EDF) and is coiled up onto a drum. The point of rotation lies well within the centre of the drum.
At the accessible space of the ring Laser formed by two beam telescopes a thin glass plate decouples the clockwise (cw) and the counter clockwise (CCW) modes of the ring Laser. By using a triple reflector also termed corner cube the ccw mode is directed in such a way that the clockwise and counter clockwise travelling modes are superimposed and their interference intensity is detected by means of the InGaAs photo detectors.

By counting the beat frequency and multiplying the result with the scale factor of the set-up one gets the angle motion of the turntable.

The turntable is driven by a micro step motor which is controlled by an extra required personal computer. Different angular speeds as well as cw and ccw are controlled by the provided software.
This gives the possibility to verify the linear relation between the beat frequency of both cw and ccw modes. Furthermore it allows to study the Lock-In effect.

 

Required Equipment
 
Cat. No. Qty. Description

Illustration


08.0560

1

SMC Fibre coupled diode laser 980 nm 80 mW

A Peltier cooled and fibre pig tailed diode laser is mounted into this unit. The emission is present at a singlemode ST socket. All functions are controlled by a micro-processor. For the operation the base unit, 08.0712 is required. Via the USB hub of the base unit a connected computer can be used to take over control through software.
The output power of the diode laser is 80 mW at a wavelength of 980 nm. Furthermore, this slot module provides an input for an external modulator.
 

08.0610

1

SMC Photodiode amplifier

Universal photodiode amplifier is a slot-in module. The frequency range of the amplifier is 0 to 1 GHz with selected 50 input impedance. The gain of the amplifier can be set in 10 steps by means of the setting knob on the front of the panel. For the operation, the base unit 08.0712 is required. Via the USB hub of the base unit, a connected computer can be used to take over the control through software.
 

08.0712


1


SMC Base unit incl. housing 4WU

A housing is prepared to accommodate 4 WU (1 WU = 70 mm) slot in modules. Whereby two width units (WU) are already occupied by the base unit providing the necessary power supply and an USB hub. Once connected to a computer, the software recognises the inserted slot-in module and control can be taken over by the software.
 


09.0322


1


Turn table with stepper motor drive

For smooth rotation of, for instance, the fibre gyroscope a motorized rotational stage with a solid base plate is used. The stepper motor is connected to the driver and control unit 19.0180. This diver provides the micro step technology by which a regular step is divided into 64000 sub steps yielding a smooth DC like operation of the rotational stage.
 


09.0324


1


Fibre laser base plate


Necessary components:
Erbium doped fibre
WDM coupler
Fringe detection unit

are mounted on top of a solid base plate which itself can be attached by means of three screws. An unique feature is the free space of the fibre resonator and the generation of the beat frequency of the CW and CCW ring laser modes. The diameter of the base plate is 310 mm and the thickness 15 mm.
 


10.0320
 

1
EXP 32 manual

No illustration


19.0180

 


1

Stepper motor controller

The stepper motor controller is connected via a RS232 serial bus to the PC. One step of the controller is internally divided into 65536 steps resulting in a smooth DC-like movement of the connected  stage.
 

Required Options
 


19.0140


1


Dual trace oscilloscope 100 MHz

Features:
Frequency Range: 150 kHz ~ 100MHz
Fully Digital Phase Locked Loop Technique Design
High Frequency Stability: ±10ppm
High Input Protection Level: +30dBm, ±25VDC
Reference Level Range: -30dBm ~ +20dBm
 


19.1000

1


IBM compatible PC including VGA monitor and keyboard

For some experiments a PC is a must whereas others can operate without one. However, some nice features may be not accessible. Due to the steadily changing models and operating systems a picture is not given. Please ask for current models.
 


No illustration

 

 

 

 

 

 

 

 

 

 


 

Laser Fundamentals
EXP 02 Detection of Light
EXP 19 Radio and Photometry
EXP 01 Emission and Absorption
EXP 03 Fabry Perot Resonator
EXP 04 Diodelaser
EXP 06 HeNe-Laser
EXP 08 Diode Pumped Nd:YAG Laser
EXP 05 Frequency Doubling
EXP 07 Generation of short pulses
EXP 31 Fibre Ring Laser NEW
EXP 20 Laser Safety

Laser Metrology
EXP 10 Laser Interferometer I
EXP 10 Laser Interferometer II
EXP 10 Laser Interferometer III
EXP 16 Laser Gyroscope
EXP 32 Laser Fibre Gyroscope NEW
EXP 21 Laser Triangulation
EXP 22 Laser Levelling
EXP 15 Laser Range Finder
EXP 29 Laser Beam Analysis
EXP 30 LDA Laser Doppler Anemometer NEW
EXP 33 Laser Vibrometer NEW
EXP 34 Laser Frequency Stabilisation NEW

Laser Material Processing
EXP 09 CO2 Experimental Laser
EXP 17 CO2 Laser Workstation 100 W
EXP 18 Nd:YAG Laser Workstation 80 W
EXP 23 Laser Maintenance & Trouble Shooting

Fibre Optics
EXP 11 Plastic Fibre Optics
EXP 12 Glass Fibre Optics
EXP 13 Optical Time Domain Reflectometry
EXP 14 Erbium Doped Fibre Amplifier
EXP 24 Workshop Glass Fibre Optics
EXP 25 Data Transmission via Glass Fibre

Miscellaneous Applications
EXP 26 Open Frame CD Reader
EXP 27 Bar Code Reader
EXP 28 Laser Scanner