Dynamic Image Analysis (DIA) is a modern particle characterization method for the determination of size distributions and shape parameters. It allows quick analyses with excellent accuracy and reproducibility over an extremely wide measuring range. With the renowned CAMSIZER system, Microtrac introduced its first Dynamic Image Analyzer over 20 years ago and has pushed technological innovation ever since.
In many applications, particle size and shape information are important process and quality indicators. With Dynamic Image Analysis according to ISO 13322-2, it is directly possible to analyze these important material properties of the sample material in a detailed and representative manner.
In Dynamic Image Analysis, a stream of particles is generated which is recorded and analyzed by a camera system. The particles are therefore in motion during the image acquisition. In most cases, Dynamic Image Analysis involves illuminating the particle stream from one side by a light source and recording the particle images as shadow projections. The particles move either in free fall (in the case of free-flowing, pourable granules), in a liquid or in an air stream, which ensures particle separation even for agglomerated powders.
Especially the last setup requires short exposure times and high acquisition rates to achieve sufficient particle detections during the measurement and to prevent motion blur. A particle measurement typically takes 1-5 minutes and usually detects tens of thousands to many millions of particles, depending on the sample.
Dynamic Image Analysis (DIA) - Functional Principle
The crucial difference between Static and Dynamic Image Analysis is that in Static Image Analysis particles are located on a carrier and do not move relative to the camera during the acquisition, such as with a microscope.
Static Image Analysis is predominantly used for measuring narrow size distributions with a focus on the characterization of very fine particles. This method provides high resolution particle images which allow for size and shape description with utmost accuracy and is mainly used in research & development applications.
Dynamic Image Analysis on the other hand is ideally suited for routine measurements of bulk goods, powders, granules and suspensions. This method is characterized by high sample throughput, reliability and excellent reproducibility.
Calibration reticle for a Microtrac CAMSIZER system
Two cameras operate during measurement: the BASIC camera (red) analyzes the larger particles, the ZOOM camera (blue) captures the small particles. This procedure ensures optimum measurement conditions for all particle sizes in a distribution.
Perfect compliance of sieve analysis and CAMSIZER P4 measurements results for granulated fertilizer
Dynamic Image Analysis can also be integrated directly into a process as an online measurement system for many applications.
The robustness of the devices allows them to be used in production environments: Dust, vibration and temperature fluctuations do not affect the measurement.
Material is continuously fed to the measuring device via an automatic sampler, changes in the process or in the product quality can thus be detected practically in real time.
The picture shows a Microtrac Dynamic Image Analysis system in online operation in a fertilizer factory.
Completely automated online system in a production environment
For many tasks in particle measurement technology, reliable detection of oversize particles is crucial, e. g. in the analysis of abrasives or the characterization of metal powders for additive manufacturing. Dynamic Image Analysis is ideally suited for such applications. If the oversize particle is detected by the camera, it will also be represented in the result.
The detection probability is extremely high thanks to the high acquisition rate of up to 320 frames per second and the large number of particles captured. In some applications, even 100% detection accuracy can be guaranteed. The example shows the analysis of a metal powder sample to which different proportions of oversize particles have been added. The Dynamic Image Analysis system CAMSIZER X2 detects even 0.005 % of large particles!
Reliable detection of oversize in a metal powder sample. The metal powder is smaller than 100 µm, the oversize is larger 200 µm. The table shows the amount of oversize added and the percentage of oversize detected by the CAMSIZER X2
The large number of particle detections in Dynamic Image Analysis brings another advantage: an extremely good repeatability of the results is achieved.
The graph shows five consecutive measurements of a 3-modal mixture of glass beads in a size range from 50 μm to 1.5 mm.
Each measurement took approximately 2.5 minutes, with 5 million particles detected per measurement.
With dynamic image analysis the repeatability is excellent
Dynamic Image Analysis is applicable for samples larger than about 1 µm. If smaller particles are also to be measured, Laser Diffraction is the method of choice.
However, this technique does not provide information on particle shape and detection of oversize particles is much less sensitive.
For this reason, Microtrac's SYNC is a novel measuring device that uniquely complements Laser Diffraction with Dynamic Image Analysis!
The SYNC is Microtrac’s most advanced laser diffraction analyzer.
Microtrac offers a wide range of instruments for Dynamic Image Analysis.
Our team of experts will be happy to advise you on your application and on our product range.
In Static Image Analysis (SIA, ISO 13322-1), particles are at rest when images are recorded, as with a microscope. In Dynamic Image Analysis (DIA, ISO 13322-2), a stream of particles is captured by a camera system. The Static method produces detailed images of a few particles, whereas Dynamic Image Analysis can evaluate many particles in very short time. As a result, repeatability and detection probability of oversize particles are significantly better with Dynamic Image Analysis.
A major advantage of Dynamic Image Analysis is the compatibility of the results with those of traditional sieve analysis. Users benefit from the shorter measuring time and thus higher sample throughput, a high level of automation (e.g. online measurement) and lower susceptibility to human errors. The time-consuming weighing and cleaning of sieves is no longer necessary with Dynamic Image Analysis.
The lower measuring range for Dynamic Image Analysis is ~0.8 µm, the largest detectable particles are ~135 mm. The lower limit of each Dynamic Image Analysis system is limited by the resolution of the cameras, the upper limit by the size of the field of view (approx. 1/3 of the image diagonal). By using two cameras in one instrument, analyzers can achieve measurement ranges with a factor up to 10.000 between lower and upper limits.
Dynamic Image Analysis is suitable for a wide range of different applications. It is used for routine quality control and production monitoring as well as for R&D tasks. Many industries are already taking advantage of the benefits of Dynamic Image Analysis. e. g. for pharmaceutical products, food, fertilizers, sand, building materials, plastics and wherever people are working with powdery or granulated products.
Thanks to the high image acquisition rate of Dynamic Image Analysis (60 - 320 images per second, depending on the device), a large number of particles are evaluated in a very short time. Thus, a meaningful result is obtained quickly. Typically, the measurement times for Dynamic Image Analysis are 1 -5 minutes. Since the measurement is contact-free, the cleaning and maintenance effort is very low.
