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Cataract is a common ophthalmic disease in which a cloudy area is formed in the lens of the eye and requires surgical removal and replacement of eye lens. Careful selection of the intraocular lens (IOL) is critical for the post-surgery satisfaction of the patient. Although there are various types of IOLs in the market with different properties, it is challenging for the patient to imagine how they will perceive the world after the surgery. We propose a novel holographic vision simulator which utilizes non-cataractous regions on eye lens to allow the cataract patients to experience post-operative visual acuity before surgery. Computer generated holography display technology enables to shape and street the light beam through the relatively clear areas of the patient's lens. Another challenge for cataract surgeries is to match the right patient with the right IOL. To evaluate various IOLs, we developed an artificial human eye composed of a scleral lens, a glass retina, an iris, and a replaceable IOL holder. Next, we tested different IOLs (monofocal and multifocal) by capturing real-world scenes to demonstrate visual artifacts. Then, the artificial eye was implemented in the benchtop holographic simulator to evaluate various IOLs using different light sources and holographic contents., 6 pages, 6 figures, conference poster manuscript

In this work, we developed a wearable, head-mounted device that automatically calculates the precise Relative Afferent Pupillary Defect (RAPD) value of a patient. The device consists of two RGB LEDs, two infrared cameras, and one microcontroller. In the RAPD test, the parameters like LED on-off durations, brightness level, and color of the light can be controlled by the user. Upon data acquisition, a computational unit processes the data, calculates the RAPD score and visualizes the test results with a user-friendly interface. Multiprocessing methods used on GUI to optimize the processing pipeline. We have shown that our head-worn instrument is easy to use, fast, and suitable for early-diagnostics and screening purposes for various neurological conditions such as RAPD, glaucoma, asymmetric glaucoma, and anisocoria., Scientific and Technological Research Council of Turkey (TÜBİTAK); 2247-A National Lead Researchers Program; European Union (EU); European Innovation Council (EIC) Horizon

Direct visualization and characterization of nanosized biological particles such as viruses, vesicles and protein aggregates are important for various applications in medicine. Specifically, exosomes (30-150 nm in diameter) gained huge interest due to their potential role as a biomarker in cancer diagnosis and prognosis, however direct detection of these particles is challenging due to their small size. Interferometric microscopy allows detection of these particles without using any labels. We show that visibility of nanoparticles can be enhanced in interferometric microscopy by utilizing defocused images. In this paper, with the proposed method Depth Scanning Correlation, we demonstrate label-free detection of individual exosomes isolated from breast cancer cell culture isolated by using Exosome Total Isolation Chip (ExoTIC). Proposed imaging system combined with an isolation tool, can be used in a wide range of applications, where label-free detection of single biological nanoparticles is needed.

Single particle level visualization of biological nanoparticles such as viruses and exosomes is challenging due to their small size and low dielectric contrast. Fluorescence based methods are highly preferred, however they require labelling which may perturb the functionality of the particle of interest. On the other hand, wide-field interferometric microscopy can be used to detect sub-diffraction limited nanoparticles without using any labels. Here we demonstrate that utilization of defocused images enhances the visibility of nanoparticles in interferometric microscopy and thus improves the detectable size limit. With the proposed method termed as Depth Scanning Correlation (DSC) Interferometric Microscopy, we experimentally demonstrate the detection of sub-35nm dielectric particles without using any labels. Furthermore, we demonstrate direct detection of single exosomes. This label-free and high throughput nanoparticle detection technique can be used to sense and characterize biological particles over a range between a few tens to a few hundred nanometers, where conventional methods are insufficient., Scientific and Technological Research Council of Turkey (TÜBİTAK)

Fluorescence based microarray detection systems provide sensitive measurements; however, variation of probe immobilization and poor repeatability negatively affect the final readout, and thus quantification capability of these systems. Here, we demonstrate a label-free and high-throughput optical biosensor that can be utilized for calibration of fluorescence microarrays. The sensor employs a commercial flatbed scanner, and we demonstrate transformation of this low cost (similar to 100 USD) system into an Interferometric Reflectance Imaging Sensor through hardware and software modifications. Using this sensor, we report detection of DNA hybridization and DNA directed antibody immobilization on label-free microarrays with a noise floor of similar to 30 pg/mm(2), and a scan speed of 5 s (50 s for 10 frames averaged) for a 2 mm X 2 mm area. This novel system may be used as a standalone label-free sensor especially in low-resource settings, as well as for quality control and calibration of microarrays in existing fluorescence-based DNA and protein detection platforms.

The afterglow emission of some gamma-ray bursts (GRBs) show a shallow decay (plateau) phase implying continuous injection of energy. The source of this energy is very commonly attributed to the spin-down power of a nascent millisecond magnetar. The magnetic dipole radiation torque is considered to be the mechanism causing the spin-down of the neutron star. This torque has a component working for the alignment of the angle between rotation and magnetic axis, i.e., inclination angle, which has been neglected in modelling GRB afterglow light curves. Here, we demonstrate the evolution of the inclination angle and magnetic dipole moment of nascent magnetars associated with GRBs. We constrain the initial inclination angle, magnetic dipole moment and rotation period of seven magnetars by modelling the seven long-GRB afterglow light curves. We find that, in its first day, the inclination angle of a magnetar decreases rapidly. The rapid alignment of the magnetic and rotation axis may address the lack of persistent radio emission from mature magnetars. We also find that in three cases the magnetic dipole moments of magnetars decrease exponentially to a value a few times smaller than the initial value. The braking index of nascent magnetars, as a result of the alignment and magnetic dipole moment decline, is variable during the afterglow phase and always greater than three., 13 pages, 8 figures, 4 tables, accepted for publication in ApJ

In this paper, we demonstrate utilization of a commercial flatbed document scanner as a label-free biosensor for high-throughput imaging of DNA and protein microarrays. We implemented an interferometric sensing technique through use of a silicon/oxide layered substrate, and easy to implement hardware modifications such as re-aligning moving parts and inserting a custom made sample plate. With a cost as low as 100USD, powered by a USB cable, and scan speed of 30 seconds for a 4mm x 4 mm area with similar to 10 mu m lateral resolution, the presented system offers a super low cost, easy to use alternative to commercially available label-free systems., NA

Current Fourier transform infrared spectroscopy (FTIR) systems have very good spectral resolution, but are bulky, sensitive to vibrations, and slow. We developed a new FTIR system using a microelectromechanical system (MEMS)-based lamellar grating interferometer that is fast, compact, and achromatic (i.e., does not require a beam splitter). The MEMS device has >10 mm2 active surface area, up to ±325 μm mechanical displacement, and a 343 Hz resonant operation frequency. The system uses a 5 MHz bandwidth custom infrared (IR) detector and a small emission area custom blackbody source to achieve fast interferogram acquisition and compact form factor. Effects of lamellar grating period, detector size, laser reference, apodization, and averaging of data on the spectral resolution are discussed. The measurement time ranges from 1.5 to 100 ms depending on the averaging time. In the target range of 2.5–16 μm (625–4000 cm−1) a spectral resolution of 15–20 cm−1 is demonstrated. The measurements are shown to be stable over a long time.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.