Rapid thickness mapping of free-standing smectic films using colour information of reflected light II: real-time areal mapping using lookup table scheme

ABSTRACT

In the previous paper [Liq Cryst. 2020; 48(6): 873–887], we demonstrated that the thickness of free-standing smectic films can be accurately determined from microscopic reflective images, solely utilising the colour information on the image. Even after full vectorisation of the computational code, however, it took ca. 0.1 ms per data point, leaving a big room of improvement to realise a true real-time 2D thickness mapping. Here, we show that the processing speed can be enhanced by a factor of 350 by using a lookup table scheme based on a modified hierarchical triangular partitioning of the colour space. A one-million-pixel image can now be captured and processed in 1 s, offering a clear path to a true video rate 2D thickness mapping.

Graphical abstract

KEYWORDS:

• Triangular mesh
• lookup table
• hierarchical triangular partitioning
• thickness measurement
• free-standing smectic films
• real-time thickness mapping
• reflective images
• MATLAB

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was supported by the National Aeronautics and Space Administration (NASA) under Grant NNX17AD68G.