SOLUTION SHEET

Rayleigh Thermometry System

Temperature imaging measurements using Rayleigh scattering

Powerful yet easy-to-use system for temperature imaging
With powerful hardware and a comprehensive processing software interface, our RayleighThermometry system offers non-contact, non-intrusive global measurement of temperature
in flames. It is well suited for instantaneous and time-averaged planar temperature imaging
in a variety of clean, particle-free combustion processes as well as gas flows with hightemperature gradients.

Key benefits•Non-intrusive imaging technique for measurements of temperature in flames•Compact yet powerful laser solution with excellent beam quality•

High-sensitivity camera•

Advanced synchronization with temporal precision down to the sub-nanosecond range•

Complete software platform for system setup, data acquisition, data analysis andvisualization of results•

Advanced software module for processing and analyzing image data from laser RayleighscatteringTemperature imaging for combustion applications
Global temperature distribution is an important parameter for the analysis andoptimization of combustion processes. By using laser Rayleigh scattering, twodimensional temperature maps can be derived from measurements in clean
combustion and hot gas flows. Our Rayleigh Thermometry system and software
provides all the tools needed for the determination of the temperature distribution
in combustion and heat transfer studies. The system utilizes green laser light insteadof UV light. With this approach we minimize the risk of exciting fuel components
or combustion intermediates which can be problematic when using UV light. Thesoftware package has an intuitive and user-friendly interface with a single dialog
for nearly all parameters used in the data processing. Advanced data analysis andcalibration routines are also provided.

The Rayleigh Thermometry system in brief
Rayleigh Thermometry data is obtained in a plane by illuminating the process underinvestigation with a thin laser light sheet. The elastically-scattered light from the gas
molecules is then recorded by an intensified camera placed perpendicular to the lightsheet. Since the intensity of the scattered light is directly related to the gas density,
we can use the grey level data from the images to determine the temperature
throughout the imaged area. The DynamicStudio software allows users to easilyacquire data with full control of all hardware from a single interface.

Overview of the different components, timing and data flow.

Laser light source
As Rayleigh scattering is a relatively weak light scattering process, the laser pulse
energy is a critical property for Rayleigh Thermometry, and thus the choice of laser
source is of great importance. The Nd:YAG laser, optimized for 10 Hz repetition rate,is equipped with a temperature stabilized 2nd harmonic generator which provides
430 mJ at 532 nm. The 2nd harmonic unit comes with intelligent auto-tuning tomaintain optimum phase matching and maintain maximum output energy over time.
The laser is easy to operate and does not require external water-cooling or othercomplex infrastructure.
Our robust Light Sheet Optics are included with the system which provide a parallellaser sheet for consistent light intensity. A parallel light sheet is required to assurethat the intensity distribution, over the laser sheet height, is the same over theobserved length of the Field-of-View. Light sheet dimensions are approx. 50 mm x 0.1mm (when used with a beam waist adjuster) with a working distance of 600 mm.
To ensure a secure working environment, laser alignment goggles and protective
goggles are also available.
Cameras, Image Intensifiers and Lenses
The standard camera for Rayleigh Thermometry is the HiSense Zyla camera (USB orframe grabber version), featuring high sensitivity and low noise levels.
The image intensifiers are designed to have the highest possible quantum efficiency
for visible light using a GaAsP or S20 photocathode, which are ideal for detecting
Rayleigh scattering. The unit offers full control over gain and gate time options,
ranging from continuous to ultra-fast, with a minimum gate time as low as 3 nsPage 2

depending on the model. Relay optics used to adapt the camera to the image
intensifier are also included.
We offer a wide range of camera lenses for visible light, together with anadapter ring for fitting filters to the selected lens. Each system includes alens to optimize the magnification and field-of-view for the scope of themeasurement along with an interference filter for Rayleigh Thermometry.
The camera and image intensifier are separate units, allowing for flexible useof the hardware. This solution is ideal for laboratories dealing with multiple
applications such as Rayleigh Thermometry, LIF, PIV, microscopy and/orspectroscopy.
High Performance Synchronizer
Synchronization of laser pulses, cameras and image intensifiers is masteredby a High Performance Synchronizer, fully controlled via the DynamicStudiosoftware. The synchronizer is a multi-channel delay and signal generator with<= 1 ns resolution. The 32 output channels are programmed independently;
thereby offering comprehensive synchronization and triggering facilitiesfor highly demanding processes. It also features four input channels forsynchronization with external devices or events, two analog inputs with up
to 500 kHz sample rate, and four analog outputs. For further details, please
consult separate data sheet on “Imaging Synchronizers”.

HiSense Zyla camera, image
intensifier unit and front lensHigh performance synchronizer

User-friendly imaging software platform - Straightforward data analysis
The image acquisition system is based on DynamicStudio, a comprehensive
and user-friendly software platform for imaging applications. It features anadvanced plug-and-play based distributed system, making it easy to get fullcontrol over the hardware for image acquisition. Data acquisition and analysis
are supported within the same software, so there is no need to export the datafor post-processing.

The Rayleigh Thermometry dialog in DynamicStudio gives the user a full overview of all parameters
used in the data processing.

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The Rayleigh Thermometry processing dialog allows you to input the values of
the test parameters such as pressure, laser pulse energy and scattering crosssection for the gas mixture in both the reference images and measurement
images. This gives you full overview of the processing from a single screen.
Background subtraction can be done automatically on all images within theRayleigh Thermometry processing to ensure that there is no systematic error
in the calculation due to camera detection noise or offset levels.
The main Rayleigh Thermometry processing features:•

Quick and robust methods to process multiple raw data sets, using the 		reference image.

•Easy access to the measurement data properties for taking parameter 		changes into account, e.g. pressure and scattering cross-section.

Species and Mixtures libraries
To make the data analysis even more straightforward, the software also includes
two libraries; one that includes several molecular species and their corresponding
scattering cross-sections, and one that includes relevant mixtures of the species
found in the first library. The global scattering cross-section for the gas mixtures
are automatically calculated and the user only needs to define what mixture wasused in the experiment, and the software takes the different scattering crosssections into account in the data processing. Of course the user is also allowedto add new species to the library and create new mixtures to create libraries
tailormade for his specific applications.
Boosting analysis capabilities with analysis sequences and MATLAB® Link
The data analysis is further strengthened by the ability to define analysis
sequences and perform batch processing which makes quick work ofprocessing large data sets. And with the MATLAB Link in DynamicStudio, you
can tailor your analysis by calling up your personally designed MATLAB scripts
directly from DynamicStudio, allowing you to process the data directly in thedatabase without the need to export.

OptionPulse Energy Monitor
A proven method of reaching higher accuracy is to measure the laser pulseto-pulse fluctuations by means of a Pulse Energy Monitor and subsequently
compensate for this during image analysis. The Pulse Energy Monitor ismounted between the laser output and light-sheet optics.

The software includes a Species
and Mixtures library making
the temperature analysis moreintuitive.

Technical specifications
Laser
Wavelength (nm)				532Pulse energy (mJ)				
430
Pulse duration (ns)			
~5Repetition rate (Hz)			
10

Light Sheet Optics
Wavelength range		

UV and visible

Light sheet height		

50 mm

Camera 					HiSense Zyla
Speed (fps) with frame 			grabber/with USB

49/40

Resolution (MP)				5.5Sensor resolution (pixels)			
2560 x 2160
Pixel size (µm)				
6.5
Lens mount				F-mount or C-mount

Image intensifiers*

H Series 18 mm

L Series 18 mm

Minimum gate time			
3 ns
Photocathode diameter 			
18 mm
Photo cathode material
GaAsP
Phosphor screen				P43Camera attachment			
C-mount
Lens attachment				F-mount

S20

Camera lenses and filters
Focal length and aperture							50mm f/1.4, 85mm f/1.4, 100
mm f/2.0

Filter adapter		Adapter for 62 mm filter 							included
Lens mount				F mountHigh Performance Synchronizer
Time resolution				<= 1 ns
Synchronization outputs			
32, TTL
Synchronization inputs			
4, TTL

Software		
DynamicStudio						Base package
Rayleigh Thermometry Add-on

Data Sheet 0563_v1. Subject to change without notice. Copyright © 2019.
Dantec Dynamics. All Rights Reserved. www.dantecdynamics.com