De-Multiplexed Multiwavelength Interferometry for High Precision Metrology

Syed Zain-Ul-Abideen Zaidi

EECS Department
University of California, Berkeley
Technical Report No. UCB/EECS-2021-222
December 1, 2021

http://www2.eecs.berkeley.edu/Pubs/TechRpts/2021/EECS-2021-222.pdf

In the era of global warming, harnessing green energy has become a top priority for nations around the world. Solar cells have been developed for over half a century, but the dull appearances of solar cells impede their widespread adaptation in size-constrained metropolitan cities like Singapore. Current colorful solar cell technologies are extremely inefficient, and their adaptation cannot be justified. In the first part of this thesis, we propose a new way to use High Contrast Gratings to materialize colorful solar cells with a very small penalty on efficiencies. We show optimized designs for Silicon, Indium-Phosphide, and Perovskite solar cells, and verify the viability of our idea through preliminary experimental demonstrations.

In the second part of the thesis, we innovate in nanoscale metrology, a key component of nanomanufacturing. Many areas of science and technology rely on the precise determination of distance over a sufficiently long range. Advanced ranging technology has the potential to open up a wide application field including 3D sensing, robotics and inspection for automated manufacturing, where high-precision, long-range, efficiency, and noise-tolerance are key. The small wavelength of light makes it a suitable candidate for precision metrology. A single wavelength interferometer has a high accuracy, but a small range that is limited by the ambiguous interferometric fringe order. We present a new arithmetic algorithm for multiwavelength interferometry that has a theoretical maximum range of the lowest-common-multiple of the wavelengths used, the resolution of a single-wavelength interferometer, and the theoretical maximum noise tolerance of an algebraic approach. We first describe the analytical formulation, analyze the noise tolerance, and present a recursive solution to extend the range through multiple wavelengths. To justify the practicality, experimental results from a simultaneous phase shifting demultiplexed two-wavelength interferometry system, with a range-resolution ratio of > 3e5, are presented to demonstrate the reliability of our method in the absence of any error correction.

Advisor: Constance Chang-Hasnain


BibTeX citation:

@phdthesis{Zaidi:EECS-2021-222,
    Author = {Zaidi, Syed Zain-Ul-Abideen},
    Title = {De-Multiplexed Multiwavelength Interferometry for High Precision Metrology},
    School = {EECS Department, University of California, Berkeley},
    Year = {2021},
    Month = {Dec},
    URL = {http://www2.eecs.berkeley.edu/Pubs/TechRpts/2021/EECS-2021-222.html},
    Number = {UCB/EECS-2021-222},
    Abstract = {In the era of global warming, harnessing green energy has become a top priority for nations around the world. Solar cells have been developed for over half a century, but the dull appearances of solar cells impede their widespread adaptation in size-constrained metropolitan cities like Singapore. Current colorful solar cell technologies are extremely inefficient, and their adaptation cannot be justified. In the first part of this thesis, we propose a new way to use High Contrast Gratings to materialize colorful solar cells with a very small penalty on efficiencies. We show optimized designs for Silicon, Indium-Phosphide, and Perovskite solar cells, and verify the viability of our idea through preliminary experimental demonstrations. 

In the second part of the thesis, we innovate in nanoscale metrology, a key component of nanomanufacturing. Many areas of science and technology rely on the precise determination of distance over a sufficiently long range. Advanced ranging technology has the potential to open up a wide application field including 3D sensing, robotics and inspection for automated manufacturing, where high-precision, long-range, efficiency, and noise-tolerance are key. The small wavelength of light makes it a suitable candidate for precision metrology. A single wavelength interferometer has a high accuracy, but a small range that is limited by the ambiguous interferometric fringe order. We present a new arithmetic algorithm for multiwavelength interferometry that has a theoretical maximum range of the lowest-common-multiple of the wavelengths used, the resolution of a single-wavelength interferometer, and the theoretical maximum noise tolerance of an algebraic approach. We first describe the analytical formulation, analyze the noise tolerance, and present a recursive solution to extend the range through multiple wavelengths. To justify the practicality, experimental results from a simultaneous phase shifting demultiplexed two-wavelength interferometry system, with a range-resolution ratio of > 3e5, are presented to demonstrate the reliability of our method in the absence of any error correction.}
}

EndNote citation:

%0 Thesis
%A Zaidi, Syed Zain-Ul-Abideen
%T De-Multiplexed Multiwavelength Interferometry for High Precision Metrology
%I EECS Department, University of California, Berkeley
%D 2021
%8 December 1
%@ UCB/EECS-2021-222
%U http://www2.eecs.berkeley.edu/Pubs/TechRpts/2021/EECS-2021-222.html
%F Zaidi:EECS-2021-222