Research
OPT Research Projects
Below is a brief description of the wide research activities of the section OPT. If interested in a project or for further information, please contact Dr. Iskander-Rizk or Dr. Bhattacharya.
Metrology
Applications of interferometric measurements extend from measuring surfaces on the nano-scale to measuring inter-satellite distances. Our goal is to push distance measurement to its limits with present technologies.
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Applications of interferometric measurements extend from measuring surfaces on the nano-scale to measuring inter-satellite distances. Our research group demonstrated a distance measurement of 50 m with 1 μm repeatability. The main limiting factor which holds the accuracy of these measurements to 25 μm is the refractive index of air. For example, a typical uncertainty of 0.2 °C in temperature or 0.5 hPa in pressure leads to an uncertainty of refractive index of air of about 5 X 10-7 which corresponds to 25 μm at 50m. In space it would be possible to test these techniques to its maximum. Our goal is to push long distance measurement to its limits with present technologies.
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Frequency combs are highly coherent lasers emitting light at multiple wavelengths (spectrally equidistant) at very stable repetition rates. This stability and coherence enable various applications namely in spectroscopic imaging (photoacoustic or optical/FTIR), distance measurement and gas identification. VIPA (Virtually Imaged Phase Array) is a combination of multi-wavelength interferometry and spectral interferometry which uses thousands of laser lines from the Frequency comb laser for distance measurement. The VIPA spectrometer shows an unprecedented resolution, unravelling the 1 GHz spaced comb frequencies to distinct modes and resolving 100 MHz comb laser into lines with 600 MHz resolution. This allows for visualizing interference of frequency comb light on the individual mode level for distance measurement interferometry.
Photoacoustics
Photoacoustics combines light and sound to achieve optical probing of materials at deeper scale than purely optical methods. When pulsed or modulated light is shone upon a material it is absorbed. The material heats up and a transient thermoelastic expansion and contraction gives way to a broadband acoustic wave. By using different optical wavelengths, different materials can be characterized and by manipulating the light and receivers different probing resolution scales can be achieved. We intend to (1) further develop photoacoustic based technology and (2) develop methodologies to extract material characteristics as a result of photoacoustic excitation.
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How can we achieve high resolution images which imaging time do not scale with the field of view? Can we use optical metamaterials to improve imaging?
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How can we probe and quantify the mechanical properties of scattering tissue? How can we extract the scattering and absorption coefficients? Are mechanical properties accessible? What can image speckle reveal?
Application
Developing the technology is one part of the OPt section activities. We go beyond and develop proof of concepts of the technology at the service of healthcare and industrial applications. We have collaborations with Erasmuc MC and LUMC in various projects.
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Through optical (and acoustic) speckle imaging we investigate flow metrology as well as mechanobiology. We also design imaging systems and develop signal algorithms for better quantification of a large range of tissue parameters. We target therapy, diagnostics but also guidance of treatment. These include flow, stroke detection, muscle strength assessment, ablation monitoring and cancer diagnostics.
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We push the limits in the development of photoacoustic catheters. We investigate new materials, manufacturing methods and designs to reach the most complex body structures. We investigate micro-optical systems and fabricate them as part of medical devices.
Selected publications
- 2021, Photoacoustic flow velocity imaging based on complex field decorrelation. Zangabad, R.P., Iskander-Rizk, S., van der Meulen, P., Meijlink, B., Kooiman, K., Wang, T., van der Steen, A.F. and van Soest, G. Photoacoustics, 22
- 2019, Laser speckle imaging of flowing blood: A numerical study, K. van As, J. Boterman, C. R. Kleijn, S. Kenjeres, N. Bhattacharya, Physical Review E, 100, 033317
- 2019, Distance Metrology with Integrated Mode-locked Ring Laser Article, K. Hei, G. Shi, A. Hänsel, Z. Deng, S. Latkowski, S.A. van Den Berg, E. Bente, N. Bhattacharya ", IEEE Photonics , Journal DOI: 10.1109/JPHOT.2019.2940068
- 2019, Real-time photoacoustic assessment of radiofrequency ablation lesion formation in the left atrium. Iskander-Rizk, S., Kruizinga, Beurskens, R.H., Springeling, G., Mastik, F., de Groot, N.M., Knops, P., van der Steen, A.F. and van Soest, G. Photoacoustics.
- 2018, Catheter design optimization for practical intravascular photoacoustic imaging (IVPA) of vulnerable plaques Iskander-Rizk, S., Wu, M., Springeling, G., Mastik, F., Beurskens, R. H., van der Steen, A. F., & van Soest, G. In Diagnostic and Therapeutic Applications of Light in Cardiology 2018 (Vol. 10471, pp. 29-36). SPIE.
- 2018. Photoacoustic-Enabled RF Ablation Catheters for Lesion Monitoring. Iskander-Rizk, S., Springeling, G., Kruizinga, P., Beurskens, R.H., van der Steen, A.F. and van Soest, G. 2018 IEEE International Ultrasonics Symposium (IUS) (pp. 1-4). IEEE
- 2017, Temperature measurement using frequency comb absorption spectroscopy of CO2, A. Hänsel, A. Reyes-Reyes, S. Persijn, H. P. Urbach, N. Bhattacharya ", Review of Scientific Instruments, 88, 053113