Kps Environment 2 D3 D Wind Profiling

Compact solutions for environmental sensing and monitoring

High Power and High Performance Fiber Lasers and Amplifiers

Applications: !   Aerosol detection !   2D/3D Wind profiling !   Weather monitoring !   Cloud height measurement !   Pollution monitoring !   Interferometric sensing ! Telemetry !   Range finding !   3D scanning !   Obstacle detection !   Airborne mapping

LIDAR (Light Detection And Ranging) is an optical remote sensing technology that measures properties of backscattered light to find range or other information of a distant target . To work the Lidar needs some form of backscattering (Rayleigh, Mie, Raman, aerosols etc, ) Remote Measurements:

Time of Flight (TOF) = Distance Frequncy shift = Velocity Depolarization = Macro composition Differential Absorption = Chemical component

2D/3D Wind profiling:

Jean-Marc Delavaux, Feb 23-2010

L idar Concept

6

Laser control

Data processing

Time-of-flight

F requency shift

Depolarization

Differential abs.

K eopsys

Pulsed

Laser

Detector

Beam forming and

steer ing optics

Solid, liquid, gas

Scattered light

collection optics

Remote M easurements:

T ime-of-F light (T O F) > Distance

F requency shift > Velocity

Depolarization > Macro composition

Differential Absorption > Chemical comp.

LIDAR - Laser Operating Mode Pulsed Lasers Most commonly used for ranging applications ¬ Remote Measurement systems include a laser transmitter, an optical telescope receiver that amplifies the backscatter, and high sensitivity photo-detector to convert optical energy into electrical impulses. Distance to object is determined by the time taken by the transmitted pulse to the target and back. Time of Flight (TOF) LIDAR

!  Non coherent source to avoid optical speckle


LIDAR - Laser Operating Mode Continous Wave (CW) Lasers Transmit a continuous signal, and ranging is carried out by modulating the phase of the laser light. Rely also on the Doppler effect. Travel time is directly proportional to the phase difference between the received and transmitted sinusoidal signal. Coherent LIDAR (Velocity Measurements)

!  Laser linewidth < 10 MHz !  Increased signal to noise ratio SNR for ranging by using spectral filtering


LIDAR - Laser Requirements (1)



Laser Requirements for L idar

10

Attr ibutes Ranging L idar Coherent L idar

Operating The must be highly reflective on the target and transparent through the mediumEye safe wavelength >1.4µm, 1.5µm is preferred, but other wavelengths ( i.e. Visible, IR) are chosen to match application requirements

Output power The range of distances is related to power level. The higher the better, provided other attributes of the source are conserved

Center

Accuracy &

Stability

Not necessary but helps SNR at receiver by additional filter.

Very important to facilitate coherent detection, in particular DIAL measurements

CoherenceL ength

Not important, Low coherent prevents speckle.

Coherent length must be equal or greater than measurement range

L ine-width ( ) Not important, may help efficiency & SNR

Linewidth must be smalller than minimum range value

LIDAR - Laser Requirements (2)



Laser Requirements for L idar (2)

11

Attributes Ranging L idar Coherent L idar

Relative intensity

noise, R IN

Not important, although may become important in multiple pulse measurement Lidar

Very important ! One of the limiting factor for the system sensitivity the higher the RIN the less sensitive be the lidarRIN<-140dBc/Hz at fc<10kHz

Sensitivity to

vibration

Not important Very important, can have detrimental effect on stability if system is used in harsh environment

Operating

temperatureGenerally important.In particular airborne /spatial, & military applications

Very important, can have detrimental effect on stability if system is used in harsh environment

Reliability Important Very important

Cost Low to moderate High to very high

LIDAR – Laser System Characteristics Pulse Energy (E) total energy content of a pulse (typically 100 µJ to several mJ). Pulse Duration (t) is usually defined as the time during which the laser output pulse power remains continuously above half its maximum value or peak power (FWHM), (i.e. 1ns to 1µs, typically 10 ns). Pulse Repetition Frequency (PRF or f) (kHz) – number of emitted pulses per second (ranges from 1 to 200 kHz) Beam Divergence (!) is usually defined by the output fiber beam divergence (i.e. M2 or BPP) limited by diffraction, typically 0.3 to 2mrad. Scan Rate –number of times per second a scanning device samples its field of view (25 –1000 Hz) Wind Power Plant Doppler Beam Swinging Profiler (principle) The flow field behind two wind turbines (symbolised by a vertical black lines)


LASER versus LIDAR parameters



Laser versus L idar Parameters

13

Laser

Parameter

L idar

ParameterRelation

Pulse Rate (PR F) Range (z) PR F(k Hz)<c/2z(m)

z=1000m => PR F<150k Hz

Pulse width ( ) Range Resolution( z)

Sample depth

(ns)=6x z(m) 10ns =>1.5m at speed of light

Beam Divergence (

Beam quality: BPP

( mm x mrad)

Trans. Resolution (Sx)

(Spot diameter )

Sx= z (mrad)

= 1 mrad @ z = 1km. Sx=1m

Energy-per-Pulse (E) SNR E SNR2

L inewidth ( )

Coherent only

Velocity (V) (MHz)< 2V(m/s) / (um)

Laser Operating Wavelength In theory, any light source can be used to create a LIDAR instrument Traditionally solid-state Nd:YAG lasers at 1064nm (NIR) & 532nm (green) wavelengths have been used in LIDARS Newer LIDAR designs and applications rely on reliable optical fiber laser technology. High performance LIDAR sources are commercially available, from Keopsys, at Visible ( 532nm), Near-Infrared (NIR-1064/1550nm) & Middle infrared (MIR-2000nm) wavelengths. Fiber lasers are attractive because they offer:

!  Combined high collimation and high optical power !  „Eye safe”, compact & low power consumption solutions !  Versatile properties adaptable to specific applications


EOLA! Series Eye-safe long pulse amplifiers

Features: !   High energy per pulse up to 100 !J !   Peak power up to 250 W !   Long pulses from 200 to 400 ns !   Repetition frequency from 10 to 20 kHz !   Fourier transformed limited operation !   Polarization Maintaining !   Diffraction limited or M2<1.5 for pulse energy >15 !J Keopsys can also provide the laser

version of this product upon request

Ideal for wind profiling by Doppler heterodyne LiDAR systems

SPIDERLITE MSA! Series Ultra compact multiple ports high power fiber amplifiers

Features: !   Multi-ports configurations from 1x30 dBm to 8x20 dBm !   Low noise figure !   Low power consumption !   Low analog signal distorsion

Ideal for: !   Sensing !   Highly integrated fiber optic systems

New! Available in PM

SPARK! Series Eye-safe CW single frequency fiber laser

Features: !   Output power up to 2 W !   Operating wavelength from 1545 to 1565 nm !   Narrow linewidth, single frequency !   Ultra low RIN !   Low phase noise !   Random or linear polarization !   Diffraction limited output !   OEM module with RS232

Ideal for wind speed measurements from windmill cradle

KULT! Series 1 !m ultra compact laser transmitter

Features: !   Pulse energy up to 10 !J !   Peak power up to 10 kW !   Pulsewidth of 0.1 ns and from 1 to 30 ns !   Repetition frequency from 10 Hz to 1 MHz !   Diffraction limited output !   Can be doubled to 532 nm

All KULT! versions are ideal for: !   Cloud height measurement !   Range finding !   Telemetry !   3D scanning

KULT! Series Eye safe ultra compact laser transmitter

1.5 "m

2 "m

1.5 !m Features: !   Pulse energy up to 50 !J !   Peak power up to 10 kW !   Pulsewidth from 0.5 to 200 ns !   Repetition frequency from 10 Hz to 1 MHz !   Diffraction limited output !   PM version available

2 !m Features: !   Pulse energy up to 15 !J !   Peak power up to 1.5 kW !   Pulsewidth from 10 to 40 ns !   Repetition frequency from 5 Hz to 20 kHz !   Diffraction limited output

MIRVISION! Series Eye-safe high power laser transmitter

Features: !   High pulse energy combined with good beam quality (80 !J and M2<1.5 or >100 !J and M2<3) !   High peak power up to 25 kW !   Pulsewidth from 1 to 10 ns !   Repetition frequency from 20 kHz to 1 MHz

Ideal for: !   Range finding !   Obstacle detection !   Airborne applications

16.03.11

Steven D. Wagner

Sales & Marketing Manager [email protected]

Direct: + 49 89 309 040 271 Cell: +49 152 56 77 77 76

The ys toYour tical

tems

LIDAR DEFENCE TELEMETRY INDUSTRY R&D TELECOM T&M MEDICAL FTTx

KEOPSYS SA. 21 rue Louis de Broglie 22300 Lannion, France Tel: +33 2 96 05 08 40 Fax: +33 2 96 05 08 01 31

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Kps Environment 2 D3 D Wind Profiling