Hillman continued working for Thorlabs and the University of Lübeck on OCT, most importantly pioneering phase-sensitive optoretinography using a full-field Fourier-domain OCT system. In December 2021, he joined the Biophotonics and Medical Imaging division of the Department of Physics as an associate professor at the Vrije Universiteit Amsterdam.
Research Description
We are interested in unique combinations of optical imaging with computational methods. While some optical imaging techniques are only possible by using appropriate algorithms, others benefit from them by improving resolution, image quality, or cost-effectiveness. We develop these methods and apply them in biomedicine.
For example, we research computational methods for optical coherence tomography (OCT) and their applications. In general, OCT is an imaging technique that sends light into tissue, detects the backscattered light, and interferometrically determines the exact backscattering location, resulting in three-dimensional tomograms of the tissue.
Using a dedicated full-field Fourier-domain OCT system, we achieve record-breaking acquisition rates of up to 100 million depth scans (A-scans) per second, reducing motion artifacts and allowing us to use the phase of the light for image reconstruction and for additional contrast.
The availability of phase in the OCT signal enables techniques from digital holography. With these, we can refocus the acquired image data and correct for aberrations. Due to the subject’s ocular aberrations, this is particularly important when imaging the human retina to obtain optimal diffraction-limited resolution. For the retina, the phase also allows us to non-invasively and label-free observe minute changes in the size of cells, i.e., photoreceptors and neurons, indicating their activity after a light stimulus. These methods have important applications in biomedical research and diagnostics.
Selected Publications
- C. Pfäffle, H. Spahr, K. Gercke, L. Puyo, S. Höhl, D. Melenberg, Y. Miura, G. Hüttmann, D. Hillmann, Phase-Sensitive Measurements of Depth-Dependent Signal Transduction in the Inner Plexiform Layer, Front. Med. 9, 2022
- L. Puyo, H. Spahr, C. Pfäffle, G. Hüttmann, D. Hillmann, Retinal blood flow imaging with combined full-field swept-source optical coherence tomography and laser Doppler holography, Opt. Lett. 47(5), 2022
- H. Spahr, C. Pfäffle, S. Burhan, L. Kutzner, F. Hilge, G. Hüttmann, D. Hillmann, Phase-sensitive interferometry of decorrelated speckle patterns, Sci. Rep. 9, 11748, 2019
- C. Pfäffle, H. Spahr, L. Kutzner, S. Burhan, F. Hilge, Y. Miura, G. Hüttmann, D. Hillmann, Simultaneous functional imaging of neuronal and photoreceptor layers in living human retina, Opt. Lett. 44(23), 2019
- D. Hillmann, H. Spahr, C. Pfäffle, H. Sudkamp, G. Franke, G. Hüttmann, In vivo optical imaging of physiological responses to photostimulation in human photoreceptors, PNAS 113 (46), 2016
- D. Hillmann, H. Spahr, C. Hain, H. Sudkamp, G. Franke, C. Pfäffle, C. Winter, G. Hüttmann, Aberration-free volumetric high-speed imaging of in vivo retina, Sci. Rep. 6, 35209, 2016
For a complete list see Dierck Hillman’s Google Scholar page
