(337b) Measurement of Crystal Morphology: A New Method Based On Reflection of Light From Crystal Faces

Measurement
of morphology of 3D faceted crystals: a new method on the basis of light
reflection from faces.

Jayanta
Chakraborty, Debasis Sarkar and Abhishek Singh

Department of
Chemical Engineering, Indian Institute of Technology Kharagpur. Kharagpur, India.

Measurement of morphology of faceted
crystals is a challenging task. Most of the examples of morphological
measurements are applicable for flat crystals where image is taken from top and
it is analyzed for edge detection. In this work we show how this simple strategy
of image capture and analysis can be used to obtain the morphology of a 3D
faceted crystal using our novel method of image capturing.

The main idea comes from the fact that
the crystal faces being smooth, regular reflection of light dominates the
irregular one. Hence a proper arrangement of optics will make one face shining where other faces will be
dull.  One such picture is shown in
Fig. 1a for CuSO₄, 5H₂O. This novel strategy makes image
processing a trivial task and the face vertices can be detected readily. The
vertex location, which is 2D information about a certain face can then be
integrated with the angular orientation of faces (which is invariant for a
given material and polymorph) to obtain the detail 3D morphology of the crystal.
One example of such reconstruction is shown in Fig. 1b.

Figure 1: (a)
The proposed illumination strategy has found a face. (b) The face features has
been extracted using image analysis and the crystal is reconstructed using our
software. The top view of the reconstructed crystal is shown.