Why Particle Size Measurement Matters
Particle size and shape directly influence the performance of powders, granules, suspensions and emulsions across industries from pharmaceuticals and food to chemicals and abrasives. A difference of just a few micrometers in mean particle size can change dissolution rate, flowability, reactivity, color strength and product shelf life. Choosing the right measurement technique is therefore critical for both product development and quality control.
Laser Diffraction: How It Works
Laser diffraction (also called laser scattering or static light scattering) measures the angular distribution of light scattered by particles passing through a laser beam. Larger particles scatter light at small angles and smaller particles at larger angles. The scattering pattern is analyzed using Mie theory or Fraunhofer approximation to calculate an equivalent sphere diameter distribution. Laser diffraction covers a wide size range (typically 0.01 µm to 3500 µm) and delivers fast, statistically robust results from millions of particles per measurement.
Dynamic Image Analysis: How It Works
Dynamic image analysis (DIA) captures high-speed images of individual particles as they pass through the measurement zone and analyzes the shape and projected area of each particle. Multiple shape descriptors — including sphericity, aspect ratio, convexity and symmetry — are calculated for each particle alongside its size. Systems like the CAMSIZER X2 use two cameras simultaneously to cover a wide size range while maintaining high resolution across all particle sizes.
Key Differences
| Parameter | Laser Diffraction | Dynamic Image Analysis |
|---|---|---|
| Size range | 0.01 µm – 3.5 mm | 0.8 µm – 8 mm |
| Shape information | Equivalent sphere only | 10+ shape descriptors |
| Sample throughput | Very high | High |
| Sensitivity to fines | High | Moderate |
| Measurement speed | 30 seconds | 1–5 minutes |
| Wet dispersion | Yes | Yes (with module) |
When to Choose Dynamic Image Analysis
Dynamic image analysis is the preferred method when particle shape is a critical quality parameter — for example, when elongated or angular particles behave differently from spherical ones of the same size. It is also valuable when identifying oversize or undersize particles that are present at low concentration but critically important for product performance. Abrasives, pharmaceutical granules, food ingredients and construction materials are common applications.
When to Choose Laser Diffraction
Laser diffraction is the preferred method for very fine particles below 1 µm, for fast routine QC where throughput is critical, and for samples where submicron fines are an important quality indicator. It is the dominant technique in pharmaceutical development and is well established in regulatory submissions.
Using Both Techniques Together
Many advanced laboratories use both techniques: laser diffraction for routine QC and rapid development screening, and dynamic image analysis to understand why batches with similar size distributions behave differently in process. The CAMSIZER product family from Retsch Technology covers the full dry and wet measurement range with both DIA and sieve correlation capabilities.
Contact NewRoad to discuss which particle size analysis solution is right for your material and application.
