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Large crystals
Small crystals

The Pixact Crystallization Monitoring (PCM) technology is designed for the online measurement of crystallization processes. The technology combines in-situ process microscopy with advanced image analysis techniques.

PCM provides a live camera view of the process and detailed real-time measurement data on crystal characteristics, such as size distribution, morphology and concentration.

The measurement results produced by PCM help you to optimize, control and troubleshoot your process efficiently. With PCM you can increase the yield and capacity of your process and minimize quality variations in the final product.

Pixscope mesurement probe with DSSE fitting
Final crystal size distribution

Equipped with flexible installation mechanics, PCM can be fitted into a variety of applications from laboratories to manufacturing-scale reactors. The technology is utilized in both continuous and batch crystallization processes. Pixact provides both transillumination and front light based measurement systems for crystallization monitoring.

See Benefits for customer reviews and benefits provided by the Pixact systems.

See Products for details on the technology utilized in the Pixact systems.


The PCM system produces detailed real-time statistics for the crystal population in the process.

The measurement results include

  • Crystal size distribution and related statistics

  • Crystal growth rate

  • Crystal morphology (aspect ratio, etc.)

  • Number of crystals in the measurement volume

  • Suspension flowability

The crystal size distribution can be processed further to calculate mean size and standard deviation, percentiles of cumulative distribution (D10, D50, D90, etc.) and fractions of fine and coarse crystals, etc.


The real-time measurement data on crystal size can be used for online process control and online quality control.

For the operator, PCM provides tools for

  • Visual examination of the crystal suspension with a live camera view (featuring zoom, pause, etc.)

  • Immediate evaluation of the seeding phase and making decisions on further actions such as reseeding

  • Online monitoring of crystal characteristics, including fractions of fine and coarse crystals

  • Detection of secondary/spontaneous nucleation and crystal dissolution

  • Batchwise reporting of complete statistics, time trends and distributions


To increase productivity and promote Best Practice methods, you can use PCM in production development for

  • Benchmarking individual reactors and recipes

  • Comparing plants with each other

  • Collecting a production database to help with troubleshooting in case of disturbances

  • Supporting lab-scale R&D work by providing new insights into crystallization dynamics and related physical phenomena

  • Supporting scale-up work by using the same measurement equipment from laboratory to production.

Excel measurement report

Boiling cystallization processes can be broken down into four stages: pre-seeding (feed liquor), seeding, growth and the final state. PCM is used for measuring and controlling crystallization processes from the very beginning until the end of each batch:

  1. PCM detects and analyzes impurities, agglomerates, droplets and bubbles in the feed liquor.

  2. During the seeding phase, the system measures the concentration and size distribution of the seeding crystals.

  3. PCM monitors the size distribution and number of the growing crystals as well as the flowability of the suspension in real time.

  4. Towards the end of the process, PCM provides information on the final crystal size distribution and other statistics.

Crystallization chart

The FL method is based on photometric stereo imaging utilizing a digital color camera and three monochromatic LED lights (red, green and blue wavelength) illuminating the crystal suspension from three directions. Three images of the same crystals are obtained at different illumination angles. The neighboring crystals can be recognized as separate as their facets show different colors according to their orientation.


​For sugar crystallization Pixact provides a front light probe as an alternative for the traditional measurement probe utilizing transillumination. The Pixact Front Light (FL) probe is designed to be installed on a reactor sight glass without direct contact with the crystal suspension.


The benefits of the FL system include:

  • Easy installation on a reactor sight glass - easy changing of measurement location

  • Portable system for troubleshooting and benchmarking between different boiling pans and sites

  • No direct contact with the suspension - no risk of contamination or leaking

  • No measurement gap - no clogging

  • Can operate at high concentration at the end of the batch

Read about our comparative study of the traditional transillumination and FL systems in our SIT 2019 conference paper.

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