Project title, ESR2: Intrinsic fluorescence excited with SC, noise, dispersion and polarisation-sensitive OCT
Aiming to improve medical diagnosis through development of optical tomography imaging systems using ultra wideband light sources.
Current projects and research areas
- Optical coherence tomography
- Polarisation noise in supercontinuum sources
- Spectral characterisation
- Rogue wave statistics
- Functional en-face OCT imaging
- Retinal decoding using a high powered supercontinuum light
- Marmalian physiological response to light stimulus
- Decoding circadian retina signalling
Motivation
Low coherence non-contact scanning interferometer like OCT uses collinear laser beam based on reflectometry principles. Analyses of backscattered signals from a balanced detector give useful information on depth, polarisation and intensity, and are used widely in medical diagnosis. Ability to extract these features in living subjects requires integration of broadband laser sources, such as high power super continuum (SC) and broadband UV lasers from NKT Photonics.
To achieve sub-micron axial range in an OCT requires broadband optical source. However, essential in achieving high axial resolutions for functional imaging, several other important parameters need to be addressed. My current research is dedicated to investigating influence of noise, dispersion, and polarisation of optical sources on microscope assembled OCT configurations.
Outreach activities
- Lab demonstration day at Prof Jackson’s career celebration 05/2015
- Day of discovery at the Beaney House 03/2015
- Buprestid beetles and spectrometer demonstration at Simon Langton Grammar School 12/2014
- Imaging the Optical Frontier Colloquium 11/2014
Professional Experience
- Development of low-noise concept for broadband optical sources with balance heterodyne detection
- Design and implementation of polarisation selection and phase decoding for OCT input
- Improved time-domain OCT system for clinical imaging
- Worked with camera based spectrometer system for high resolution optical imaging
- Implement multimodal functional imaging system by combining flourescence, confocal and dual-channel OCT system
- Characterisation of dispersion in optical system with a novel narrowline acousto-optic tunable filter module
- Devised an automated retina imaging system with broadband supercontinuum light to study pupillary light reflex in mouse
- Participated in performance analyses of en-face OCT and master/slave imaging on clinical tissues
- Developed two optical pump and terahertz probe optical spectroscopy systems
- Generation of ultra broadband 20 THz wave using advanced LT interdigitated photoconductive antennas and non-linear electro-optic crystals
- Generation of mid-infrared and deep UV conversion using high-energy optical parametric amplifiers.
- Characterisation of ultrafast dynamics in 2D heterostructure materials such as TiO2, graphene, hBN and MoS2
- Implement a novel drug delivery system to study sub-second neurotransmitter dynamics with femtosecond lasers
- Devised an automated high precision temperature controlled feedback monitoring system for ultrafast laboratory
Education
- 2014 to 2017 PhD in Physics University of Kent, UK
- 2013 to 2014 Masters of Science in Telecoms Telecom Bretagne, France
- 2006 to 2010 Bachelor of Engineering in Electronics Multimedia University, Malaysia
Publications
List of peer review publications
- Applied Optics, 55(26), 7378-86, (2016) doi: 10.1364/AO.55.007378.
- Status: Published
- Title: Master/slave optical coherence tomography imaging of eyelid basal cell carcinoma
- Authors: Chin, A. Bradu, R. Lim, M. Khandwala, J. Schofield, A. Podoleanu
- Abstract: Optical coherence tomography (OCT) has becoming an increasingly dominant method for tumour detection and diagnosis. A master-slave interferometer (MSI) was assembled to detect periocular basal cell carcinomas (BCC) using a modified OCT configuration. A swept source at 1300 nm and sweeping speed of 50 kHz was used. Three steps process was involved. First, 384 memories of channelled spectra from a mirror were stored for 384 optical path differences, then they were correlated with channelled spectrum from the BCC tissue to produce 384 en-face images (200×200 pixels). Finally, these en-face slices were stacked to form a volume to cross-reference BCC tumour margins in orthogonal plane (B-scans). With MSI, we reduced imaging time to only 3.2s per eyelid sample. En-face images showed superior discrimination of BCCs comparable to cross-sectional (B-scan) using previously published time domain and FFT based OCT techniques.
- Applied Optics, 55, Issue 21, pp. 5707-5714, (2016), doi.org/10.1364/AO.55.005707
- Status: Published
- Title: Acousto-optic tunable filter for characterization of dispersion in time-domain optical coherence tomography system
- Authors: Chin, F. Toadere, L. Leick, T. Feuchter, A. Podoleanu
- Abstract: A broadband super continuum light source together with an acoustic-optic tuneable filter (AOTF), are used to characterize the dispersion in two time domain OCT systems, at 830 nm and 1300 nm. The filter is designed to sweep across two spectral ranges: one from 500 nm to 900 nm, and the other from 1150 nm to 2000 nm. Dispersion compensation for 830 nm was achieved with a spectral delay line. Dispersion compensation for 1300 nm was achieved using BK 7 rod glasses in the reference arm. The AOTF allows evaluation of dispersion in under as well as over compensated systems. The AOTF method is based on wavelength dependence of the optical path difference (OPD) corresponding to the maximum strength of the coherence gate recorded with a mirror used as object. Comparison is made between the AOTF method and the method based on measurement of the full-width half-maximum (FWHM) of the autocorrelation peak. This comparison shows that the AOTF method is more accurate in terms of evaluation of the dispersion left uncompensated after each step. The AOTF method additionally providing information on the direction of dispersion compensation.
- Submitted to Biomedical Optics Express (2017-2018)
- Status: awaiting review process
- Title: Use of a super continuum white light in evaluating the spectral sensitivity of the pupil light reflex
- Authors: Chin, L. Leick, A. Podoleanu, G. S. Lall
- Abstract: We assessed the spectral sensitivity of the pupillary light reflex in mice using a high power super continuum white light (SCWL) source in a dual wavelength configuration. This novel approach was compared to data collected from a more traditional setup using a Xenon arc lamp fitted with monochromatic interference filters. Irradiance response curves were constructed using both systems, with the added benefit of a two-wavelength, equivocal power output using the SCWL. The variables applied to the light source were intensity, wavelength and stimulus duration through which the physiological output measured was the minimum pupil size attained under such conditions. We show that by implementing the SCWL as our novel stimulus we were able to dramatically increase the physiological usefulness of our pupillometry system.
- Optics Express (2017-18)
- Status: In progress
- Title: Polarization extinction ratio and intensity noise of long-pulse supercontinuum sources
- Authors: Chin, R. Engelsholm, P. Moselund, T. Feuchter, L. Leick, A. G. Podoleanu, and O. Bang
- Abstract: We investigate the polarization of supercontinuum generated in nominally non-birefringent silica photonic crystal fibers over the entire spectrum of the source (450-2400 nm). We demonstrate that the polarization extinction ratio (PER) varies over the spectrum and in particular that it increases with wavelength from zero at the blue edge to over 10 dB at the red edge for all pump power levels from 30% to 100% of the maximum. We experimentally demonstrate how the spectrally resolved polarization develops with increasing power and along the length of the nonlinear fiber. We experimentally measure an increase of the birefringence of the nonlinear fiber with wavelength and discuss how this fact combined with nonlinear processes can explain the observed PER. We experimentally measure the relative intensity noise (RIN) and show that it is similar for the two polarizations.
- Optics Letters (2017-18)
- Status: In progress
- Title: High-speed two-spectrometer based broadband polarization-sensitive optical coherence tomography with supercontinuum source
- Authors: Chin, T. Feuchter, P. M. Moselund, L. Leick, O. Bang, A. Podoleanu
- Abstract: We demonstrate a low-cost practical application of a supercontinuum based dual-spectrometer broadband polarization-sensitive optical coherence tomography (PS-OCT) for detecting valuable documents such as counterfeit bank notes. By retrieving multi-layered birefringence of liquid crystal and dichroic pigment, we could investigate the light polarization and axis rotation of a sample given its material composition. To achieve ultra broadband imaging, we use a supercontinuum source with bespoke polarization manipulation.
List of peer review conference papers
- SPIE Photonics West LASE Conference 2017, San Francisco, CA, USA, SPIE 10089, Real-time Measurements, Rogue Phenomena, and Single-Shot Applications II, 100890L (21 April 2017); doi: 10.1117/12.2253478; https://doi.org/10.1117/12.2253478, Presentation recording on the SPIE Digital Library:http://dx.doi.org/10.1117/12.2253478.5387835751001
- Date: 30 January 2017
- Place: San Francisco, CA, USA
- Status: Accepted
- Title: Polarization extinction ratio and polarization dependent intensity noise in long-pulse supercontinuum generation
- Authors: Chin, Catherine; Engelsholm, Rasmus Dybbro; Moselund, Peter Morten; Feuchter, Thomas; Leick, Lasse; Podoleanu, Adrian; Bang, Ole
- Category: Oral presentation + exhibition
- Sub-conference: Real-time Measurements, Rogue Phenomena, and Single-Shot Applications II
- Abstract: We investigate the polarization of supercontinuum generated in nominally non-birefringent silica photonic crystal fibers over the entire spectrum of the source (450-2400 nm). We demonstrate that the degree of polarization varies over the spectrum but that some parts of the spectrum show stable polarization extinction ratios (PER) of over 10 dB. We experimentally demonstrate how the spectrally resolved polarization develops with increasing power and along the length of the nonlinear fiber. The experimental results are compared to numerical simulations of coupled polarization states mimicking the experimental conditions. Subsequently, a single-shot pulse-to-pulse polarization dependent relative intensity noise (PD-RIN) was measured and the noise characteristics were analyzed using longtailed and rogue wave statistics. To do this, we used a range of 10 nm narrow bandpass filters (BPF) between 550 nm to 2200 nm, and fast photo detectors, to record 800 consecutive pulses. Peaks from these pulses are first extracted, then distribution of their pulse height histogram (PHH) is constructed. Analysis using higher-order moments about the mean (variance, skewness and kurtosis) showed that: (1) around the pump wavelength of 1064nm, the PD-RIN is lowest, PHH exhibits a Gaussian distribution, and higher order moments are zero, (2) further away from pump, PD-RIN increases in parabolic fashion, PHH follows a left-skewed long-tailed Gamma distribution, and higher-order moments increase. Spectrally, the difference of the PD-RIN in the two orthogonal axes increases with PER.
- 2nd Canterbury Conference on OCT, SPIE 10591, 2nd Canterbury Conference on OCT with Emphasis on Broadband Optical Sources, 1059105, 6-8 Sept 2017, (5 March 2018), 6-8 Sept 2017; doi: 10.1117/12.2286064; https://doi.org/10.1117/12.2286064
- Date: 6-8 September 2017.
- Place: University of Kent (UK).
- Category: Oral presentation.
- Title: “Use of a Super continuum white light in evaluating the spectral sensitivity of the pupil light reflex”.
- Authors: Catherine Chin, Lasse Leick, Adrian Podoleanu, Gurprit S Lall
- Abstract: We assessed the spectral sensitivity of the pupillary light reflex in mice using a high power super continuum white light (SCWL) source in a dual wavelength configuration. This novel approach was compared to data collected from a more traditional setup using a Xenon arc lamp fitted with monochromatic interference filters. Irradiance response curves were constructed using both systems, with the added benefit of a two-wavelength, equivocal power, output using the SCWL.The variables applied to the light source were intensity, wavelength and stimulus duration through which the physiological output measured was the minimum pupil size attained under such conditions. We show that by implementing the SCWL as our novel stimulus we were able to dramatically increase the physiological usefulness of our pupillometry system.
List of further attended conferences/workshops/events
- Professor David Jackson Career Celebration
- Date: 21-22 May 2015.
- Place: University of Kent (UK).
- Category: Poster presentation.
- Title: “En-Face OCT Imaging on Basal Cell Carcinomas”
- Authors: Catherine Chin, Adrian Bradu, Rongxuan. Lim, Mona Khandwala, John Schofield, Adrian Podoleanu
- 1st UBAPHODESA workshop
- Date: 24-25 September 2015.
- Place: NKT Photonics (Denmark).
- Category: Oral presentation.
- Title: “Acousto-optic tuneable filter for dispersion characterisation of an OCT system”
- Authors: Catherine Chin. Florin Toadere, Lasse Leick, Thomas Feuchter, Adrian Podoleanu
- Mid-term review
- Date: 22 January 2016.
- Place: University of Kent, SPS (UK).
- Category: Oral presentation.
- Title: “UBAPHODESA mid-term review meeting – project status update”
- Authors: Catherine Chin.
- 2nd UBAPHODESA workshop
- Date: 29-30 September 2016.
- Place: University of Kent, SPS (UK).
- Category: Oral presentation.
- Title: “Polarisation sensitive OCT and polarisation dependent intensity noise in supercontinuum generation”.
- Authors: Catherine Chin, Rasmus Engelsholm (DTU), Peter Moselund (NKT), Thomas Feuchter (NKT), Lasse Leick (NKT), Ole Bang (DTU), Adrian Podoleanu (UoK).
- NKT Engineering Meeting
- Date: 22 August 2016.
- Place: NKT Photonics (Denmark).
- Category: Oral presentation.
- Title: “To update NKT technical staff a full overview on UBAPHODESA work planned and en-face OCT development at NKT”.
- Authors: Catherine Chin, Lasse Leick.