Dynamic Opticswavefront sensor

New paper published in Micromachines. In this article we survey the physics, engineering strategies, and recent implementations of photonic nanojets for high-throughput generation of arbitrary nanopatterns, along with applications in optics, electronics, mechanics, and biosensing. An outlook of the potential impact of nanopatterning technologies based on photonic nanojets in several relevant biomedical areas is also provided.

Refraction occurs because waves travel at different speeds in different mediums and this change in speed is caused by differences in density between the mediums. The angle of refraction is larger or smaller than the angle of incidence depending on how the speed changes:

Deformable lens

We are happy to be part of Organvision, a technology proposal to image organoids in real-time and label-free. The project has been funded 3.7 million Euros by Horizon 2020 under the prestigious FET Open RIA program. Organvision comprises of 8 partners spread across 5 cities in 4 countries: Norway (Tromso), Germany (Hamburg, Berlin), Italy (Milan), and Spain (Barcelona).

As with reflection we have an angle of incidence, but instead of an angle of reflection we have and angle of refraction:

High power deformable mirror

Light waves are often referred to when discussing reflection, refraction and diffraction. However, these behaviours also apply to other waves including sound waves and the other waves in the electromagnetic spectrum, the effects may just not be as great.

The ICREA Academia program has awarded Dr. Duocastella one of their grants! These awards distinguish the research career of teaching staff working at one of the eight Catalan public universities.

New paper published in Journal of Physics Photonics! In In this review paper, we survey the main applications of acousto optic deflectors (AODs) in neuroscience, from fluorescence imaging to optogenetics. We also review the theory and physical mechanisms of these devices and describe the main configurations developed to accomplish flexible illumination strategies for a better understanding of brain function.

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New paper published in Optics and Lasers in Engineering! In this article, we show how the combination of an acousto-optofluidic lens (TAG lens) with pulse illumination enables quantitative phase imaging (QPI) at rates only limited by the camera frame rate. We demonstrate the feasibility  of our approach by measuring different dynamic samples, including an evaporation droplet at rates exceeding 100 phase maps per second. The ease of implementation and tunability of the proposed system opens the door to democratizing QPI in fluid dynamics, histopathology and other fields involving thin transparent samples.

New paper published in Advanced Materials Technologies! In this article, we present a novel fabrication process compatible with any wet printing method that allows for microlens fabrication with tuned focusing performance. Our approach, called “print-n-release”, is based on modifying the geometry of printed prepolymer microdroplets by using a reconfigurable substrate. Specifically, we used flexible elastomeric materials subject to different types of stress. Upon release, and provided pinning of the contact line, the microdroplets deform because of substrate shrinking. Following a UV-curable step, the microdroplets can then be converted into microlenses whose final shape is no longer dictated exclusively by the wetting behavior between prepolymer and substrate.

When a wave travelling through a medium (such as air) hits the surface of another medium (such as a mirror) it is reflected.

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The size of the aperture (or object) determines the extent of diffraction, with the most significant diffraction occurring when the aperture is of the same order of magnitude as the wavelength of the wave.

Dr. Martí Duocastella has been invited to participate in the 2nd International Workshop on Frontiers in Lasers and Applications (FLA-2)

Our research focuses on novel optical methods for three-dimensional light engineering, with applications in materials science, sensing, and biology. Key examples of our work in this area include the development of laser catapulting for additive micro-optics manufacturing, acousto-optofluidic systems for focusing and shaping the light at sub-microsecond time scales, and fast inertia free optical microscopes for unprecedented volumetric imaging speed and particle tracking.

New paper published in Applied Surface Science. Here, we present a theoretical and experimental study on the effects that film rigidity, elasticity, and plasticity play on laser catapulting. By combining the thermodynamic equations of the laser-generated propulsion force with the theory of thin plate bending, we derived an analytical model that fully describes the list of events responsible for disk ejection. The model is in good agreement with experiments using elastomers, polymers, and metals. A complete printability map based on the film mechanical parameters is reported, which can help to broaden the family of materials suitable for laser additive manufacturing.

New paper published in Scientific Reports! In In this article, we show that ultrasound waves featuring a Bessel-like profile can locally modulate the optical properties of a turbid medium to facilitate light guiding. Supported by wave optics and Monte Carlo simulations, we demonstrate how ultrasound enhances light focusing a factor of 7 compared to conventional methods based on placing optical elements outside the complex medium. Combined with point-by-point scanning, images of samples immersed in turbid media with an optical density up to 15, similar to that of weakly scattering biological tissue, can be reconstructed.

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New paper published in Ultrasonics! In In this article, we report how combining wavefront sensing and Schlieren tomography enables rapid and direct quantification of 3D pressure fields while obviating any calibration steps. By simultaneously capturing optical phase and intensity information of the US-perturbed fluid using a Wavefront Sensor and Schlieren projections, respectively, 3D pressure fields over several millimeters cubic can be reconstructed after a few seconds. We present a detailed description of the approach and prove its feasibility by characterizing the US field after an acoustic lens, which is in excellent agreement with calibrated hydrophone measurements and simulations.

Dr. Martí Duocastella, Dr. Pietro Ricci, Mr. Narcís Vilar and Mr. Christos Alexandropoulous presented their works at SPIE Photonics West 2024.

New paper published in Nanophotonics! Here, we present a scan-less technology that allows sub-micrometric imaging at thousands of frames per second.We use two acousto-optic deflectors (AODs) placed in a Mach–Zehnder interferometer and drive them simultaneously with multiple acoustic frequencies. As a result, orthogonal light stripes are obtained that interfere at the sample plane, forming a two-dimensional array of flickering spots. The light from the sample is collected with a single photodiode that, after spectrum analysis, allows for image reconstruction at speeds only limited by the AOD’s bandwidth and laser power.

Large aperture deformable mirror

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The diagram below illustrates a wave being reflected by a surface. Instead of drawing the actual wave a ray is drawn as it is much simpler than drawing the actual wave.

New paper published in Journal of Colloid and Interface Science in collaboration with the Laboratory of Nanotechnology for precision medicine at IIT. In this article, we show how two-photon polymerization in microfluidic channels is a suitable technique for the continued fabrication of anisotropic micro-particles in the sub-10 µm range. The proposed approach could support the fabrication of micro-hydrogels of well-defined morphology, stiffness, and surface properties for the sustained release of therapeutic agents.

Dynamic opticsdeformable mirrors

New paper published in Nature Communications! In this paper, we propose a method for dramatically increasing the speed of topographic optical imaging. Instead of the traditional plane by plane interrogation of the surface of interest, our idea is based on performing a binary search. Specifically, we collect a reduced set of images, each integrated during a full focal scan, whilst the illumination is synchronously modulated. The high speed of the technique and its ease of implementation could enable a paradigm shift in optical metrology, allowing the real-time characterization of large or rapidly moving samples.

When the aperture is larger than the wavelength most waves pass through and little diffraction occurs and when the aperture is much smaller than the wavelength most waves are blocked.

New paper published in Measurement Science and Technology! In this article, in collaboration with the company Sensofar SL, we present an optical system that features a large numerical aperture of 0.3 and a wide field of view (FOV) of 2.9 x 2.9 mm. Such a system is capable of characterizing additively manufactured parts in a single measurement, without the need for lateral stitching to increase the FOV. The proposed system exhibits optical properties that provide facility for large-field, high-resolution measurement of industrially-produced additively manufactured parts.

When a wave passes from one medium to another (such as from air to glass) the direction of the wave changes. This change in direction is called refraction.

The diagram below shows a wave being diffracted. Most waves will be partially reflected and partially refracted. However, for simplicity only refraction is shown in the diagram.

New paper published in ACS Photonics! In this article, we propose an innovative method for high-speed volumetric light-sheet microscopy. It is based on simultaneously illuminating the sample with a stack of parallel light-sheets created with acousto-optic deflectors. By using an extended depth-of-field detection system, all sample planes appear in focus, and the corresponding information can be acquired in a superimposed single frame. After applying a single-step inversion algorithm, a stack of frames can be decoded into a volumetric image whose signal-to-noise ratio and contrast are greatly enhanced. The method shows promise toward the investigation of fast dynamic sub-cellular processes in thick biological samples.