Measuring the Three-Dimensional Morphology of Crystals Using Regular Reflection of Light

Abstract

In this paper we present a new technique for measuring the three-dimensional (3D) morphology of faceted crystals. This new technique is based on the observation that a significant amount of regular reflection of light happens from flat crystal faces. Innovative lighting and camera arrangement is used to obtain the photograph of the crystal where a face is highlighted by huge contrast from the background. Such photographs are used to identify the location of the face corners using an in-house method as well as with the well-known Harris corner detector. The in-house method is found to be of comparable efficiency as the Harris detector. Using a simple algorithm, the 3D face coordinates are generated from the two-dimensional face coordinates. Finally, the 3D coordinates of the corners are used to reconstruct the crystal. A consistency check is employed during the reconstruction step which corrects for any missing corner or inconsistent data.

In Situ Measurement of 3D Crystal Size Distribution by Double-View Image Analysis with Case Study onl-Glutamic Acid Crystallization

“…An offline 3D shape measurement method was developed based on assembling the 2D surface images of a crystal captured by using a regular reflection of light. 22 Another off-line 3D size measurement method 23 was proposed for cuboid crystals such as β-form…”

“…For monitoring the crystal growth quality, it was pointed out that 2D image analysis methods could provide relatively less information than those of 3D imaging methods. − Bujak and Bottlinger adopted three orthogonally installed cameras to measure 3D sizes of particles with irregular shapes, but not for imaging crystals in the slurry. An off-line 3D shape measurement method was developed based on assembling the 2D surface images of a crystal captured by using a regular reflection of light . Another off-line 3D size measurement method was proposed for cuboid crystals such as β-form LGA, by using a multiprojection imaging system consisting of one camera and two mirrors.…”

Quantitative Evaluations with 2d Electrical Resistance Tomography in the Low-Conductivity Solutions Using 3d-Printed Phantoms and Sucrose Crystal Agglomerate Assessments

“…Based on the underlying physical principle involved and characteristics (i.e., offline, online, or in situ) of the process, a variety of process analytical technology (PAT) sensors are utilized in process control systems. Crystallization process monitoring as well as crystal morphology assessments are performed using various PAT modalities such as light reflection [ 1 ] and confocal microscopy [ 2 ] for morphological measurements and CCD cameras [ 3 ], and hot stage microscopy [ 4 ] for observation of suspensions. The 3D surface measurements to measure particle size [ 5 ], Raman spectroscopy, ultraviolet (UV), mid-IR spectroscopy, and focused beam reflection measurements (FBRM) [ 6 ] to observe polymorphic transformations are some of the advanced PAT technologies in crystallization monitoring.…”

Quantitative Evaluations with 2D Electrical Resistance Tomography in the Low Conductivity Solutions Using 3D Printed Phantoms for Crystallization Process Monitoring

“…Based on the underlying physical principle involved and characteristics (i. e. offline, online, or in situ) of the process a variety of process analytical technology (PAT) sensors are utilized in process control systems. Crystallization process monitoring as well as crystal morphology assessments are performed using various PAT modalities such as light reflection [1] and confocal microscopy [2] for morphological measurements and CCD cameras [3] and hot stage microscopy [4] for observation of suspensions. The 3D surface measurements to measure particle size [5], Raman spectroscopy, Ultraviolet (UV), mid-IR spectroscopy, and focused beam reflection measurements (FBRM) [6] to observe polymorphic transformations are some of the advanced PAT technologies in crystallization monitoring.…”