Low-power Laser Light Research Articles

Light-Driven, Dynamic Assembly of Micron-To-Centimeter Parts, Micromachines and Microbot Swarms.

This work describes light-driven assembly of dynamic formations and functional particle swarms controlled by appropriately programmed light patterns. The system capitalizes on the use of a fluidic bed whose low thermal conductivity assures that light-generated heat remains "localized" and sets strong convective flows in the immediate vicinity of the particles being irradiated. In this way, even low-power laser light or light from a desktop slide projector can be used to organize dynamic formations of objects spanning four orders of magnitude in size (from microns to centimeters) and over nine orders of magnitude in terms of mass. These dynamic assemblies include open-lattice structures with individual particles performing intricate translational and/or rotational motions, density-gradient particle arrays, nested architectures of mechanical components (e.g., planetary gears), or swarms of light-actuated microbots controlling assembly of other objects.

Super-resolution vibrational imaging based on photoswitchable Raman probe.

Super-resolution vibrational microscopy is promising to increase the degree of multiplexing of nanometer-scale biological imaging because of the narrower spectral linewidth of molecular vibration compared to fluorescence. However, current techniques of super-resolution vibrational microscopy suffer from various limitations including the need for cell fixation, high power loading, or complicated detection schemes. Here, we present reversible saturable optical Raman transitions (RESORT) microscopy, which overcomes these limitations by using photoswitchable stimulated Raman scattering (SRS). We first describe a bright photoswitchable Raman probe (DAE620) and validate its signal activation and depletion characteristics when exposed to low-power (microwatt level) continuous-wave laser light. By harnessing the SRS signal depletion of DAE620 through a donut-shaped beam, we demonstrate super-resolution vibrational imaging of mammalian cells with excellent chemical specificity and spatial resolution beyond the optical diffraction limit. Our results indicate RESORT microscopy to be an effective tool with high potential for multiplexed super-resolution imaging of live cells.

The Virtual Retinal Display: A Technology for Augmented Reality

Abstract: Virtual Retinal Display (VRD) is an advanced technology for creating visual images. Dr. Thomas A. Furness III created it at the Human Interface Technology Laboratory (HIT Lab). Low power laser light is directly scanned onto the retina by the VRD to produce images. Bright, high-contrast, high-resolution photos are produced with this unique technique. It has been shown that all the technological advancements needed have been made in order for small, laser-scanned, virtual retinal displays to operate effectively. Since several years ago, military and commercial customers have received prototype devices with VGA resolutions (640 x 480 pixels), and Microvision's Virtual Retinal DisplayTM (VRDTM) is now ready for accelerated performance expansion. VRD images often use 300 nanowatts or less. Additionally, VRD images can be easily seen when placed on ambient room lighting.

The effects of low power laser light at 661 nm on wound healing in a scratch assay fibroblast model

Wound treatment, especially for chronic and infected wounds, has been a permanent socio-economical challenge. This study aimed to investigate the ability of red light at 661 nm to accelerate wound healing an in vitro wound model using 3T3 fibroblasts. The purpose is further specified in clarifying the mechanisms of wound closure by means of intracellular ROS production, proliferation and migration of cells, and cellular orientation. Illumination effects of red light from a diode laser (661 nm) at different doses on 3T3 cell viability was assessed via MTT assay and tested in a scratch wound model. Wound closure rates were calculated by image analysis at 0, 24, and 48 h after laser treatment. ROS production was monitored and quantified immediately and 24 h after the treatment by fluorescence microscopy. Cellular orientation was quantified by image analysis. No phototoxic energy doses used and increased cell viability in most of the groups. Scratch assay revealed an energy interval of 3 – 4.5 J/cm2 that promote higher wound healing rate 24 h post treatment. An increase in ROS production was also observed 24 h post irradiation higher in the group with the highest wound healing rate. Also, cellular orientation toward the margin of the wound was observed and quantified after irradiation. Low power laser light at 661 nm activated both the migration and proliferation in the in vitro model used, providing evidence that it could also accelerate wound healing in vivo. Also, ROS production and cellular orientation seem to play an important role in wound healing process.

Plasmonic heating of protected silver nanowires for anti-frosting superhydrophobic coating

Atmospheric frosting and icing pose significant problems for critical and common-use infrastructures. Passive anti-frosting and anti-icing strategies that require no energy input have been actively sought, with no viable and permanent solutions known yet. Bioinspired superhydrophobic (SH) materials have been considered promising path to explore; however, the outcome has been less than compelling because of their low resistance to atmospheric humidity. In most cases, condensing water on an SH surface eventually leads to mechanical locking of ice instead of ice removal. Hybrid strategies involving some form of limited energy input are being increasingly considered, each with its own challenges. Here, we propose the application of plasmonic heating of silver nanowires (AgNWs) for remote frost removal, utilizing an SH hybrid passive-active system. This novel system comprises a durable nanocomposite covered with a hydrophobized mesh of AgNWs, protected against environmental degradation by a tin oxide (SnO2) shell. We demonstrate the frost removal ability at −10 °C and 30% RH, achieved by a combination of plasmonic heating of AgNWs with a non-sticking behavior of submicrometric droplets of molten frost on the SH surface. Heating was realized by illuminating the mesh with low-power blue laser light. Adjustment of the nanowire (NW) and shell dimensions allows the generation of surface plasmon resonance in illuminated NWs at a wavelength overlapping the emission maximum of the light used. In environmental stability tests, the nanostructures exhibited high atmospheric, mechanical, and thermal stability. The narrow-wavelength absorption of the structure in the blue light range and the reflective properties in the infrared range were designed to prevent protected surfaces from overheating in direct sunlight.

Photobiomodulation: Evolution and Adaptation.

Photobiomodulation (PBM) can be described as the intentional use of low-power laser or light-emitting diode light in the visible and near-infrared light spectra as a medical treatment to living biological tissues. This article describes the evolution of photochemical reactions on Earth, the mitochondria, and their implications in PBM; the science of light and energy (necessary to understand the mechanisms of PBM); and the clinical science of light as therapeutic medicine. Finally, selected reviews of current treatment protocols and ongoing research regarding the possibilities for the use of PBM in the human body are examined.

High-fidelity laser-free universal control of trapped ion qubits.

Universal control of multiple qubits-the ability to entangle qubits and to perform arbitrary individual qubit operations1-is a fundamental resource for quantum computing2, simulation3 and networking4. Qubits realized in trapped atomic ions have shown the highest-fidelity two-qubit entangling operations5-7 and single-qubit rotations8 so far. Universal control of trapped ion qubits has been separately demonstrated using tightly focused laser beams9-12 or by moving ions with respect to laser beams13-15, but at lower fidelities. Laser-free entangling methods16-20 may offer improved scalability by harnessing microwave technology developed for wireless communications, but so far their performance has lagged the best reported laser-based approaches. Here we demonstrate high-fidelity laser-free universal control of two trapped-ion qubits by creating both symmetric and antisymmetric maximally entangled states with fidelities of [Formula: see text] and [Formula: see text], respectively (68 per cent confidence level), corrected for initialization error. We use a scheme based on radiofrequency magnetic field gradients combined with microwave magnetic fields that is robust against multiple sources of decoherence and usable with essentially any trapped ion species. The scheme has the potential to perform simultaneous entangling operations on multiple pairs of ions in a large-scale trapped-ion quantum processor without increasing control signal power or complexity. Combining this technology with low-power laser light delivered via trap-integrated photonics21,22 and trap-integrated photon detectors for qubit readout23,24 provides an opportunity for scalable, high-fidelity, fully chip-integrated trapped-ion quantum computing.

Polarization purity for active stabilization of diode laser injection lock.

Injection locking of diode lasers is commonly used to amplify low power laser light but is extremely sensitive to perturbations in the laser current and temperature. To counter such perturbations, active stabilization is often applied to the current of the injection locked diode. We observe that the diode laser's polarization extinction ratio (PER) greatly increases when injection locked, and therefore the PER provides a measure of injection lock quality. We report robust active stabilization of a diode laser injection lock based on the PER, demonstrating the technique at 399nm wavelength where injection locking is typically less stable than at longer wavelengths. The PER provides a feedback error signal that is compatible with standard proportional integral differential servo controllers, requires no additional optical components beyond the optical isolator typically used in injection locking, and enables a large feedback bandwidth.

Application of digital holographic microscopy to evaluate the dynamics of a single red blood cell influenced by low-power laser light

In the paper, a shift of individual human erythrocytes drifts speed, stimulated by various low-power lasers irradiation, was studied by digital holographic microscopy (DHM). Well known in physiotherapy, a low-level-laser-therapy (LLLT) scanner was used as the stimulation light source, with diode and He-Ne lasers to compare.In the article, an open-source image processing algorithm for simultaneous dynamics and geometrical properties evaluations of the red blood cells is proposed. A strong influence of the low-level red light on the red blood cells dynamics was observed. The effect is important for a better understanding of the laser treatment mechanism.The proposed phase image analysis algorithm significantly improves the individual cells tracing precision for a life science application. The programme might be useful for optical tweezer, imaging flow cytometry, or high precision cells-photon interaction research.

In Vitro Biostimulation of Low-Power Diode Pumping Solid State Laser Irradiation on Human Serum Proteins.

Objective: This research is conducted to clarify whether the action of low-power diode pumping solid state (DPSS) laser doses modify proteins of normal human blood serum in vitro. Background data: Low-power laser light is considered to act through biostimulation rather than through thermal effects. It was found that low-power laser light biostimulates various biological processes, such as increasing the blood flow within the microcirculation. Methods: Human blood serum samples were carefully collected and divided into five equal aliquots. One of them served as a control (nonirradiated serum) and the other four aliquots were irradiated by DPSS laser at a wavelength of 589 nm with different doses (50, 70, 90, and 110 J/cm2). The electrophoretic migration speeds of each specific protein were measured immediately after irradiation using protein electrophoresis. A paired Student's t-test was used between variables. Results: The protein concentrations were not significantly (p > 0.05) changed by the various doses of DPSS laser comparing with the nonirradiated counterpart. The electrophoretic migration speed of serum proteins was significantly decreased in almost all tested doses relative to the nonirradiated counterpart. Moreover, the irradiation of serum proteins (albumin, alpha1, alpha 2, beta, and globulin) with a laser dose of 70 J/cm2 was associated with a significant decrease (p < 0.003, 0.02, 0.002, 0.02 and 0.001, respectively) in protein migration speed compared with the protein migration speed of the control nonirradiated counterpart. Conclusions: Laser light at a wavelength of 589 nm induces processes that lead to decreases in serum protein migration speeds. Globulin protein was found to have the lowest migration speed among the other plasma proteins.

Application of Laser Blue Light With a Wavelength of 405 nm in the Treatment of Patients With the Virus COVID-19.

Dear Editor, Scientists are concerned about a new virus that has infected tens of thousands of people and killed more than 2,000. The virus, which emerged in the Chinese city of Wuhan in December, is a coronavirus and belongs to the same family as the pathogen that causes severe acute respiratory syndrome, or SARS. It causes a respiratory illness called COVID-19, which can spread from person to person.[1] Laser and Virus Fatma Vatansever Together with their research team in the year 2013 they came to this conclusion by testing on viruses and pathogens UVC, blue light, PDI have been shown to be effective in inactivating pathogens without harm [2].Research on the use of lasers in viral mortality is not widespread, but with a few studies, the effectiveness of laser blue light and LEDs in eliminating the virus can now be studied. Diem ThoHo, with his research team studying 400 nm blue light, concluded thatThe results of this study provide the first evidence that 405-nm LED light has antiviral activity [3]. there are some wavelengths that can decrease microorganisms directly, such as blue, ultraviolet, or violet wavelengths. We can increase these effects by possibly combining this method with another method known as antimicrobial photodynamic therapy (aPDT).&nbsp; According to mechanisms mentioned earlier, we are referring to the capabilities of PBM and photodynamic therapy. The best use is a combination of both methods, as mentioned earlier. The present treatments are focused on virus removal, tissue oxygenation, and reduction or inhibition of cytokine storm caused by severe inflammation. With a combination of these two methods, we can achieve these goals with minimal interference with pharmaceutical methods and battle this disease with biophysical agen [4]. The Blue Laser: Blue laser light of different wavelengths has been reported to have positive effects on our immune system. Can be used for anti-microbial photodynamic therapy&nbsp; (for bacterial, viral and parasitic diseases) [5]. Based on past studies and the effectiveness of low-power laser light, we can use venous laser light in this method intravenously, but it should be noted that using blue light in a venous form is more cautious. Therefore, the use of this method should be all factors such as: Age, gender, weight, specific disease, and laser duration were considered so that we could do this properly.The wavelength used will be 405 nanometers with a power of 1.5 to 2 milliwatts, which due to the high energy of this wavelength should not exceed the mentioned power, and the duration of laser radiation according to the factors from 10 to 20 minutes in 10 sessions. There will be a day in between The goal is to reduce inflammation of the lungs and increase the amount of nitric oxygen that will increase the body's immunity and improve oxygen delivery to the blood and tissues.

Gut-lymph-lung pathway mediates sepsis-induced acute lung injury.

This review attempts to unveil the possible mechanisms underlying how gut lymph affects lung and further gives rise to acute respiratory distress syndrome, as well as potential interventional targets under the condition of ischemia-reperfusion injury. We searched electronic databases including PubMed, MEDLINE, Cochrane Central Register of Controlled Trials, Google Scholar, Web of Science, and Embase to identify relevant literatures published up to December 2019. We enrolled the literatures including the Mesh Terms of “gut lymph or intestinal lymph and acute lung injury or acute respiratory distress syndrome.” Gut is considered to be the origin of systemic inflammation and the engine of multiple organ distress syndrome in the field of critical care medicine, whereas gut lymph plays a pivotal role in initiation of ischemia-reperfusion injury-induced acute respiratory distress syndrome. In fact, in the having been established pathologic model of sepsis leading to multiple organ dysfunction named by Gut Lymph theory, a variety of literatures showed the position and role of changes in gut lymph components in the initiation of systemic inflammatory response, which allows us to screen out potential intervention targets to pave the way for future clinic and basic research.

Case Report: Single visit photo-activated disinfection in regenerative endodontics

Background: Root canal disinfection is considered critical for achieving successful regenerative endodontic procedures. Photo-activated disinfection is a novel disinfection method that can help to achieve the goal of regenerative endodontics. This article reports the clinical and radiographic results after single visit regenerative endodontics using photo-activated disinfection. Methods: An 8.5-year-old girl complained of fractured upper right central incisor. Pulp necrosis was diagnosed on the basis of clinical findings. The root canal was irrigated with sodium hypochlorite solution (1.5%) followed by saline. Then, the canal was dried with paper points. A combination of a photosensitizer solution and low power laser light were applied. EDTA solution was used as a final irrigant. Bleeding was induced, followed by placement of collagen resorbable matrix and white mineral trioxide aggregate. Two days later, the tooth was sealed and restored with permanent filling. Results: Clinical findings revealed no pain on percussion or palpation tests. Radiographic examination revealed an increase in root length, an increase of apical root thickness and apical closure at the 12-month follow-up period. Conclusion: Regenerative endodontics using photo-activated disinfection achieved successful outcomes in the necrotic immature permanent tooth.

In vitro anti-tumor effect of high-fluence low-power laser light on apoptosis of human colorectal cancer cells.

Colorectal cancer is the third most common malignancy all over the world, along with high morbidity and mortality. As a treatment, high-fluence low-power laser irradiation (HF-LPLI) has reported that its biostimulatory activity can suppress or even destruct tumor growth in neoplastic diseases. The aim of the present study is to examine a therapeutic capacity of HF-LPLI for colorectal cancer treatment by using human colon cancer cell (HT29) model. The in vitro cancer cell model was used to analyze the underlying mechanism of laser-induced apoptosis. Laser irradiation was performed five times (once a day for five consecutive days) with 635nm laser light for 8 and 16min (fluence = 128 and 256J/cm2), respectively. The efficiency of the HF-LPLI treatment was evaluated by MTT, fluorescence staining, cell wound healing, and western blot test during the 5-day period. Experiment data showed that HF-LPLI had a dose-dependent stimulating effect on cell viability, migration, and apoptosis of HT29 cells. The inhibition effect of laser treatment at 256J/cm2 on cell viability was statistically significant. Meanwhile, the wound healing and western blot tests also confirmed that HF-LPLI could inhibit cell migration and induce cell apoptosis. The current research results demonstrate that 635nm HF-LPLI can be an alternative treatment option for colorectal cancer by increasing the expression of caspase-3 and inducing HT29 tumor cell apoptosis through activation of the mitochondrial pathway.

Diseño e Implementación de un Sistema Bifrecuencial Basado en Láseres de Baja Potencia

El presente trabajo describe el diseño e implementación de un sistema bifrecuencial que puede ser usado como alternativa para el tratamiento de enfermedades en la boca mediante la irradiación de luz láser de baja potencia. El sistema es un prototipo, cuyo diseño mecánico es creado en un software de uso libre para luego ser impreso en un modelo 3D el cual alberga toda la parte electrónica y óptica. En cuanto a la parte electrónica, se monta sobre varios módulos los cuales cumplen diferentes funciones como son: el cargador de la batería, convertidores de potencia, drivers para los disparadores, una pantalla OLED que muestra información de los sensores, todo el proceso y mandos tanto manuales como automáticos son controlados por una tarjeta de desarrollo. El sistema óptico comprende de; un arreglo de espejos que básicamente dan el direccionamiento a la luz de los láseres y hacen que incidan sobre un mismo punto, al final se integra una fibra óptica para poder ingresar a partes inaccesibles en la boca para el tratamiento. Para validar el prototipo implementado, se realizaron mediciones tanto de la irradiancia como de la potencia en equipos especializados para estas aplicaciones, a más de basarse en revistas odontológicas y artículos de salud publicados por distintos institutos y universidades.

P1.17-02 The Investigation of Intraoperative Marking by Transbronchial Low Power Laser Irradiation in Human Lung

Small lung nodules which appear to be ground glass opacity in peripheral lung are difficult to identify during surgery. In order to identify the site of such lesions, various types of preoperative or intraoperative marking methods have been reported. However, there is no definitive way. Therefore, we have reported a new safe and reliable intraoperative marking method using low power laser light. By irradiating low power laser close to the lesion from a bronchus, the site of the lesion can be identified from the lung surface by looking at the laser light. We conducted an animal experiment and were able to observe the laser light irradiated in bronchus from the lung surface. In this study, we performed laser irradiation to the resected human lung to confirm whether the laser light can actually be observed safely from lung surface. The patient was 70-year-old male (40 pack-years ex-smoker). The adenocarcinoma (55×40mm) was located at right S2 area. Immediately after right upper lobectomy, a plastic cylindrical-type laser probe was inserted into peripheral bronchus of the resected lung. The probe was very thin (0.8mm diameter) and flexible. Therefore, it can be inserted into the peripheral lung. It was developed jointly with Keio University. The probe was induced just below the pleura and 70mW low power laser irradiation was performed. We examined whether laser light could be confirmed from lung surface. The effect of laser irradiation to the lung tissue was evaluated pathologically. When the probe was guided to just below the pleura, laser light could be clearly observed from the lung surface. After that, the probe was gradually withdrawn. The laser light could be observed until the depth of 10mm from the pleura. No damage was obtained around the laser irradiated area in pathological findings. The observable depth of laser light was slightly shallow at10mm. The reasons of this were guessed that lung expansion was not sufficiently because harvested lung was used, so the density of lung tissue was increase and pleural thickening and anthracosis were observed in the lung because of his smoking history. It might be possible to confirm the localization of small nodules in peripheral lung using low power laser light during surgery.

Light-sheet microscopy with length-adaptive Bessel beams

In light-sheet microscopy, a confined layer in the focal plane of the detection objective is illuminated from the side. The illumination light-sheet usually has a constant beam length independent of the shape of the biological object. Since the thickness and the length of the illumination light-sheet are coupled, a tradeoff between resolution, contrast and field of view has to be accepted. Here we show that scanned Bessel beams enable object adapted tailoring of the light-sheet defined by its beam length and position. The individual beam parameters are obtained from automatic object shape estimation by low-power laser light scattered at the object. Using Arabidopsis root tips, cell clusters and zebrafish tails, we demonstrate that Bessel beam light-sheet tailoring leads to a 50% increase in image contrast and a 50% reduction in photobleaching. Light-sheet tailoring requires only binary amplitude modulation, therefore allowing a real time illumination adaptation with little technical effort in the future.

Superresolution stimulated Raman scattering microscopy using 2-ENZ nano-composites.

Superlensing plays a crucial role in near- and far-field optical imaging with sub-wavelength resolution. One of the ways to expand optical bandwidth is surface plasmon resonances in layered metal-dielectric nanostructures. These resonances are commonly excited at a tunable single frequency. In this study, we propose the concept of a multimode far-field superlens made of a titanium oxynitride (TiON) thin film, that is a disordered metal-dielectric refractory nano-composite. These films exhibit a double epsilon-near-zero (2-ENZ) behavior near the percolation threshold and, therefore, favor super-coupling the incident laser light to surface plasmon resonances, not using such couplers as a prism, a grating, etc. We experimentally observe stimulated Raman gain emission from nano-structured TiON thin films exposed to low-power continuous-wave laser light. It is shown that superresolution of <λ/80 (near-field) and <λ/8 (far-field) is achieved due to both the enhanced third-order optical nonlinearity and the multiplicative nature of four-wave mixing. The multimode tunable far-field superlens will impact emerging diffraction-free far-field optical microscopy, random Raman lasing on meta-atoms and broadband thermophotovoltaics.

P1.16-010 Development of a Novel Surgical Marking Method Using Low Power Laser Light

P1.16-010 Development of a Novel Surgical Marking Method Using Low Power Laser Light

Precise spatio-temporal control of rapid optogenetic cell ablation with mem-KillerRed in Zebrafish

The ability to kill individual or groups of cells in vivo is important for studying cellular processes and their physiological function. Cell-specific genetically encoded photosensitizing proteins, such as KillerRed, permit spatiotemporal optogenetic ablation with low-power laser light. We report dramatically improved resolution and speed of cell targeting in the zebrafish kidney through the use of a selective plane illumination microscope (SPIM). Furthermore, through the novel incorporation of a Bessel beam into the SPIM imaging arm, we were able to improve on targeting speed and precision. The low diffraction of the Bessel beam coupled with the ability to tightly focus it through a high NA lens allowed precise, rapid targeting of subsets of cells at anatomical depth in live, developing zebrafish kidneys. We demonstrate that these specific targeting strategies significantly increase the speed of optoablation as well as fish survival.