SOLUTION SHEET

ShadowSizer system

Characterization of particle size, velocity, shape, and more

Advanced imaging based particle flow characterization

Ranging from natural phenomena to industrial processes, multi-phase flows areeverywhere. For pure scientific research or applied flow diagnostics, the measurementof velocity fields by phase is required for their complete understanding. From solid
particles in air or liquids to bubbly/slurry flows; these applications benefit from imagebased processing, rather than from point-based instruments.
The ShadowSizer measurement solution is ideal for understanding complex multiphaseflow processes, such as spray break-up, bubble growth, condensation, spatial particle
size distributions, and size/velocity correlation. The ShadowSizer system is a complete
solution that can directly measure the particle size, velocity, and shape based on
shadow imaging so there is no need to have spherical particles or information about thecomposition to obtain accurate results.

Key benefits•Wide range of applications: droplets, bubbles, solid particles – static or in flows•

Instantaneous measurement of region in space at low or high frequencies•No prerequisite information about the particles is required•

Intuitive, easy to set up and use - what you see is what you get•Particle size range down to 3 µm

Easy to use shadow sizing measurement solution
The ShadowSizer solution for mapping of size, velocity, and shape in
multi-phase flow processes is very much “what you see, is what you get”.
Therefore, the system is very easy to operate – in fact, just as simple as
taking a picture. The solution consists of an application-specific camera
and a backlighting source such as an LED, or a strobe with laser light,aPC, and the DynamicStudio software package. The ShadowSizer enables
image acquisition and analysis within the same platform. For the camera,
three different long distance microscopes are offered, all of which arecoupled with various objectives to adapt to different applications.

System setup including light source, camera with long distance microscope, software,and electronics.

Working principle
A light source is used to back illuminate an object and a camera acquires
the shadow image. For a particle flow, a short light flash and an accurate
synchronization device are used to freeze the particle motion. The image
is analyzed with an advanced segmentation algorithm to extract particle
size and shape information. The velocity information is extracted via a
dedicated particle-tracking algorithm.

ShadowStrobe, Long-Distance Microscope Type-I, FlowSense EO 5M camera ShadowSizer
system measuring droplets in an agricultural hollow-cone spray.

The solution in brief
The system includes a high-resolution CCD or CMOS camera, a long-range
microscope lens, a light source, and calibration target and software. Thesolution can be configured by selecting various cameras, optics (cameralens), and illumination devices to match your application in the best
possible way in terms of velocity and particle size range, as well as themeasurement area.

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Light source
Two different light sources are offered – laser based ShadowStrobe or
ShadowStrobe LED – for back-illuminating the measurement object. Bothlight sources are speckle free, able to provide a very uniform and brightbackground, and are easy to control through DynamicStudio software.
ShadowStrobe LED•High intensity, non-coherent pulsed light•

Collimated and beam divergence adjustment•

Pulse duration as short as 100 ns•

Repetition rates up to 100 KHz•

Compact, simple connection, and space saving

ShadowStrobe LED backlight, 25 mm
aperture model on a post.

ShadowStrobe optics•

Used with lasers via a flexible liquid light guide•

Uniform collimated and speckle-free background illumination•

Wide choice of lasers with various pulse energies and repetition rates•

Required for high-speed sprays or flows up to several hundred meters
per second•

Variable illumination area by means of focus adjustment

ShadowStrobe light source with aliquid light guide.

CameraA wide range of CCD and CMOS cameras are available to meet theapplication requirements. Depending on the need, either double-frame ortime-resolved systems can be configured.
With focus on particle statistics, the double-frame FlowSense FCX cameras
provide short inter-frame times and small pixel size at high resolutions,allowing you to measure particle distributions in a wide dynamic range ofsizes and velocities, even in supersonic flow applications. With the latest
CMOS backside illuminated sensors, they provide great sensitivity, extended
dynamic range coupled with extremely robust blooming suppression forclean imaging even in the most challenging applications.
With focus on transient phenomena, the SpeedSense CMOS series ofcameras deliver frame rates up to twenty thousand images per second
at full resolution, allowing you to capture complex physical processes intime, such as: bubble formation/coalescence, liquid fragmentation, solidformation/separation, etc.
Please refer to separate data sheets on our FlowSense, HiSense andSpeedSense cameras.

Long Distance Microscopes
To avoid contamination of the imaging system from the measurement object(e.g., a spray), and to minimize the intrusion and interference of the wholemeasurement system with the particle flow, a long distance microscope isneeded to measure small particles at relatively long working distances.
Two families of lenses are offered to obtain the high image magnification
required in these cases. first, the Long Distance Microscope Type Q/I/T series
provide a wide range of magnification ratios and working distances, giving
the flexibility needed in different measurement conditions.
And second, with a fixed optical configuration, the Telecentric Lens series
provide maximum accuracy for specific applications.
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FlowSense FCX and SpeedSense cameras.

Long Distance Microscope – Type Q
The Type Q offers the highest magnification, required for measurement ofsmall particles in narrow field of views.
• Max. Magnification ratio: ~12.5• Max. working distance: 1520 mm• Features: Large magnification ratio; multiple options of objectives
Long Distance Microscope – Type I/T
The Type I/T are very easy to handle. Both include an adjustable apertureand a focusing ring. With similar working distances and magnification ratios,
the Type I fits full-frame image sensor formats, while the Type T fits smaller
4/3” ones, but with nearly constant magnification focusing allowing you tomeasure particle size more accurately.
• Max. Magnification ratio: ~3.8
• Max. working distance: 675 mm• Features: Easy handling; adjustable aperture; adaptable to all image 		sensor formats
Telecentric Lenses
When the application is known in terms of magnification and working
distance, telecentric lenses offer distortion-free and constant magnification
imaging across the depth of field, making them the perfect choice foraccuracy in particle sizing.
• Max. Magnification ratio: 1.0• Max. working distance: 400 mm• Features: Constant magnification; no focusing or adjustment required.

Long Distance Microscope, Type Q.

Long Distance Microscope Type I.

Long Distance Microscope Type T.

All types of long-distance microscopes are delivered together with dedicatedbrackets and mounting plate, allowing them to be combined with all theHiSense, FlowSense, and SpeedSense cameras.
Calibration Target
The Shadow Calibration Target helps to minimize bias on the size
measurements. It has a multi-frequency grid distortion pattern allowing you
to perform a Shadow Size Calibration, together with DynamicStudio and theShadow Sizing Add-On. By acquiring images at different out-of-focus depth
locations, three main calibration outputs can be applied: size correction,
depth location, and depth of field (DOF) correction for particle statistics.

Telecentric Lenses 132/1.0 and 400/1.0
models.

Selection of camera and optics
In general, the selection of the correct microscope and its parameters depends
on the minimum particle size to be resolved. As a rule of thumb, at least 5 pixels
are needed to resolve one imaged particle. To build an example, if the pixel size
Shadow Calibration Target. For particleof the camera is 3.5 μm and the magnification ratio is 1.5, then the minimum
sizes from 10 to 1000 µm.
.
.
droplet/particle size that can be resolved is √(5 4/π) 3.5/1.5 ≈ 5.9 μm (based on theprojected area equivalent diameter).
To measure the velocity of particles, short pulses of light are required to “freeze”
them in the field of view, and enough repetition rate to track them in the subsequent frames. When double-frame images are required, these can be obtained by
all the offered cameras, whereas time-resolved tracking can only be obtained by theSpeedSense series.
We consider a 100 µm particle size as a reference, allowing it to move a maximumof 10% of its diameter to be considered frozen in-frame, setting the minimum pulse
width of the strobe light. To track this particle in time, a maximum displacementof 80 pixels between frames is considered, setting the minimum repetition rate toaccurately build the particle matches between frames or tracks.
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For a quick overview of measurement range depending on camera, longdistance microscope and light source, please see table below.

Measurement range – for various hardware combinations. The FOV and Minimum Size are calculated
based on the maximum magnification of the Long Distance Microscopes.
The maximum velocity is calculated based on particle with 100 μm, except cases for the Type Q, wherea particle of 10 µm was considered – lower maximum velocity must be expected for smaller particles(the diffraction caused by the iris is not considered). For the SpeedSense cameras, both double-frame
and time-resolved maximum velocity are reported at nominal framerate.

Mounting solutions
The Bench for Optical Systems is a modular tool for mounting and alignment ofillumination sources, calibration targets, and imaging systems. The Bench for
Optical Systems Base Kit consists of a solid 1500 mm optical grade profile of 95
mm square section.
The included 3-feet design keeps everything stable in a table-top configuration.
The length of the profile allows for quick and accurate change of the camera
optics’ working distance, always maintaining optical alignment.
Changing the working distance allows for exploring different fields of view.
Works perfectly with variable configurations of Long Distance Microscope Type
Q/I/T and the FlowSense or SpeedSense camera series. Moreover, by using theBench Accessory Mounting Kits, both the illumination source ShadowStrobe
LED (or laser-based) and the Shadow Calibration target can be mounted in thecamera optical axis.

Bench Accessory Mounting Kit used to place the ShadowStrobe LED 50/B and the Shadow CalibrationTarget. Bench Lens Mounting Kit used to mount the Long Distance Microscope Type T, together with
the FlowSense EO 5M camera.
Page 5SpeedSense camera mounted together
with a Long-Distance Microscope Type T
in an optical Bench.

Software
The ShadowSizer software is an add-on to DynamicStudio, the innovative,flexible, and easy to use software platform for imaging-based measurements.
The hardware configuration is easy thanks to the use of plug and play devices
and configuration wizards. The software platform assists you throughout
the entire process from setting up the system, through data acquisition,processing, and presentation.
Image analysis and data processing
The acquired images containing particle shadows reveal geometric
information for each particle. Our advanced Adaptive Shadow Tracking
detection algorithm ensures that the correct geometry and size is measured.
Together with this, the state-of-the-art Shadow Size Calibration method helps
to improve the accuracy and precision of the size measurements, allowing
you to calculate even the depth position of the particles.
For each detected object, the following parameters are measured:•••••••Position (x, y)
Depth (|z|)
Velocity vectors
Shape factor
AreaEccentricity
Contrast••••••

Equivalent diameter
Calibrated diameter
Perimeter
Equivalent volume
Major/minor axis lengthOrientation

The particle velocity is determined using the particle displacement
information between two successive images. The results are computed byusing our Particle Tracking Velocity (PTV) algorithm.

Particle information overlay from water
droplets: detected contours, calibrated
equivalent diameter, V-velocity, andabsolute depth location (z).

Adaptive Shadow Tracking method in DynamicStudio. Particle detection in a hollow-cone agricultural spray. Results areshown using the particle display overlay and table, allowing to quickly visualize key parameters such as velocity, size,eccentricity, etc.
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Advanced processing and particle statistics
In traditional particle sizing by shadow imaging only 2D information iscommonly available. The “what you see is what you get” principle applies,
allowing you to calculate the position and shape parameters of particles
in the x-y field of view.
Newer image processing techniques allow you to go beyond the 2D
measurement plane using a single camera, allowing you to obtain theabsolute depth position by calculating the particles’ degree of defocusing.
We called this 2.5D Shadow Sizing in DynamicStudio.

Combined workflow of shadow measurements in a spray. Adaptive Shadow
Tracking showing the measured particles overlayed on the image (lower left).
Shadow Correlation showing the overall Size-Speed correlation of droplets(lower right). Shadow Statistics showing the aggregated DOF-corrected particle
size probability cumulative density functions (upper right). 2.5D representation ofthe particle sizes and velocities, thanks to the Shadow Size Calibration depth
distance estimation (upper left).

Key particle size statistics such as D10, D32, D43, Dv10, Dv50, Dv90
and Span are calculated when applying the Shadow Statistics method.
Particle size distributions can be approximated by particle size or volume
histograms as counts or probability/cumulative density functions.
Moreover, used together with the depth of field (DOF) estimation fromthe Shadow Size Calibration, the inherent bias from shadow imaging canbe corrected, increasing the precision of the overall statistics.
Other statistical quantities like particle Volume Fraction or Volume Fluxes
can be estimated using the DoF calibration. All the statistics can also
be shown in a numerical display and can be exported easily to be postprocessed using external tools (e.g. MATLAB, Octave, Python, Excel, etc.)

Size Correction of defocused particles,distance estimation and DOF. Built
using the Shadow Size Calibration
method.
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Ordering information
The typical components for the ShadowSizer solution are listed here. Foradditional information on other relevant cameras, lasers etc., please contact
your local Dantec Dynamics representative.

Category

Item

Item noLight source

ShadowStrobe LED 25-50/B
DualPower 65-15 Laser 2 x 65 mJ at 15 Hz, 532 nm
ShadowStrobe Optics for laser beam diameter <4 mm

83X46
38A7533
65X55

CameraFlowSense FCX 5M-124 2448 x 2048 pc 124 fps
SpeedSense VEO E 340 2560x1600 px, 800 fps

81C84
84C15MicroscopeLong Distance Microscope Type-Q
Long Distance Microscope Type-T
Telecentric Lens 132/1.0M C-Mount for max 2/3” Sensors
Shadow Calibration Target

81X1283X32
83X36
83X28Mounting

Bench for Optical Systems Base Kit. 1500 mm long
Bench Lens Mounting Kit. Rail carriage and side extension
Bench Accessory Mounting Kit. Rail carriage side extension
Bench Kit SpeedSense VEO E. Rail carriage side extension

83X29
83X33
83X41
83X47

SoftwareDynamicStudio Base Package
Dynamic Studio ShadowSizer Add-on

80S57
80S48

Traverse

3D Traversing Mechanism Range 610mmx610mmx610mm
3-D Traversing Controller, line voltage 100-250V
Traverse Option for DynamicStudio

41T33
41T19
80S76

Electronics

Performance Synchronizer
Performance Imaging PC for a 1-Camera imaging system
CoaXpress12 Frame Grabber 4 channels for FlowSense FCX Series

81N2081N1181C81

Solution Sheet 0520_v5. Subject to change without notice. Copyright © 2022.
Dantec Dynamics. All Rights Reserved. www.dantecdynamics.com