Introduction

The ISO 13322 series is applicable to the analysis of images for the purpose of determining particle size distributions. The purpose of this document is to provide guidance for measuring and describing particle size distribution, using image analysis methods where particles are in motion. This entails using techniques for dispersing particles in liquid or gas, taking in-focus, still images of them while the particles are moving and subsequently analysing the images. This methodology is called dynamic image analysis.

There are several image capture methods. Some typical methods are described in this document.

ISO 13322-1 on static image analysis methods assumes that an adequate image has already been captured and concentrates upon the analysis of these images.

Scope

This document describes a method to transfer the images from particles having relative motion to binary images within practical systems, in which the particles in the images are individually separated. Images of moving particles are created by an optical image capture device. Effects of particle movement on the images are either minimized by the instrumentation or corrected by software procedures. This method is applicable to the particle images that are clearly distinguishable from static background. Further processing of the binary image, which is then considered as static, is described in ISO 13322-1. A dynamic image analysis system is capable of measuring a higher number of particles compared to static image analysis systems. This document provides guidance on instrument qualification for particle size distribution measurements by using particulate reference materials. This document addresses the relative movement of the particles with respect to each other, the effect of particle movement on the image (motion blur), the movement and position along the optical axis (depth of field), and the orientation of the particles with respect to the camera.

Principle

4.1 Key components of a dynamic image analyser

Each system designated as a dynamic image analyser consists of the following essential key components.

Additionally, some optional components can be used to either enhance the quality of the measurements or to deal with particular set-up characteristics:

a) essential:

— illumination,

— particle feed,

— optical system,

— image capture device,

— image analysis,

— conversion to meaningful particle size parameters, and

— statistical representation of descriptors;

b) optional:

— particle dispersers, and

— particle positioning.

A general diagram for dynamic image analysis is shown in Figure 1 and Figure 2. The illumination can be set-up in a transmitted light arrangement (see Figure 1), in a reflection arrangement (see Figure 2) or in a combination of both. In a reflection arrangement, a reflecting device, the vessel wall or even the particles can reflect the light back through the measurement zone as transflected light. The type of lighting has a great influence on the appearance of the particle images.

*Contact us (sales@goldapp.com.cn) to get this downloaded PDF*