A number of methods have been available in industrial microscopy for measuring the materials in a sample. This article discusses the similarities and differences of three specific methods: phase analysis, porosity analysis, and particle distribution. All of these three methods use light and color thresholding techniques to determine materials in samples. However, the methods break out data differently.
Phase Analysis
Phase Analysis is one of the most basic approaches of detecting and sorting multiple materials present in samples. When a sample is viewed under a microscope, each material is observed as a distinct color or gray value (a phase). These materials have been separated by the imaging software, which sets thresholds for each specific material.
Each material or phase is represented as a percentage of the entire image or of an area of interest, enabling users to quickly discover if the proportions of materials in the sample are correct. Phase Analysis is typically used in composite materials, steel microstructures, die casting, and in welding quality checks.
Porosity Analysis
Porosity Analysis starts in the same way as Phase Analysis, but yields information specific to the pores being measured. Here, the pores in samples are identified using thresholding. As pore size is a key parameter in most cases, pores that are too large or too small can be removed using filters.
Since a porosity percentage is outputted together with maximum pore size and pore density, the ensuing results can be based on the area of interest or the entire image. Typical applications for this type of analysis include porosity in foams and voids in chemical materials.
Particle Distribution
Though there is similarity in the working of Particle Distribution, this method allows distributing data into different categories based on size. Based on applications, size can be considered differently. Size classifications can be defined by using options such as area, equivalent circle diameter, or Feret max.
It is also possible to consider classification distribution differently based on applications, allowing the selection of options for particle percentage, particle count, or area-weighted particle percentage. Particle Distribution is typically used to determine stability in suspension such as paints and sediments, texture and feel of, for instance, food ingredients, efficiency of delivery such as asthma inhalers, and appearance of, for instance, inks and powder coatings.
Other Analysis Methods
If the aforementioned methods are not able to fulfill the specific requirements of users, a comprehensive object detection and classification solution can be used. Materials in a sample are identified by Count and Measure, using threshold detection.
Classification and Distribution can be carried out by over 50 different options that include pixel properties, shape, position, and size. It is possible to use filters along with each classification to fine-tune the ensuing data. It is also possible to output all data to workbooks and reports, enabling users to clearly present their results.
This information has been sourced, reviewed and adapted from materials provided by Evident Corporation - Industrial Microscopy.
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