Light Modulator Research Articles

Visualization of cecal tumor by near-infrared laparoscopy and intraoperative colonoscopy

BackgroundIn laparoscopic colorectal surgery, accurate localization of a tumor is essential for ensuring an adequate ablative margin. Therefore, a new method, near-infrared laparoscopy combined with intraoperative colonoscopy, was developed for visualizing the contour of a cecal tumor from outside of the bowel. The method was used after it was verified on a model that employed a silicone tube.Case presentationThe patient was a 77-year-old man with a cecal tumor near the appendiceal orifice. Laparoscopy was used to clamp of the terminal ileum, and a colonoscope was then inserted through the anus to the cecum. The laparoscope in the normal light mode could not be used to identify the cecal tumor. However, a laparoscope in the near-infrared ray mode could clearly visualize the contour of the cecal tumor from outside of the bowel, and the tumor could be safely resected by a stapler. The histopathological diagnosis of the resected specimen was adenocarcinoma with an invasion depth of M and a clear negative margin.ConclusionsThis is the first report of the laparoscopic detection of the contour of a cecal tumor from outside the bowel. This technique is useful and safe for contouring tumors in laparoscopic colorectal surgery and can be used in various surgeries that combine endoscopy and laparoscopy.

OVERVIEW OF THE INFLUENCE OF INNOVATIVE TECHNOLOGIES ON EXPANDING THE FUNCTIONAL CAPABILITIES OF AUTOMOBILE HEADLIGHTS, ON THEIR PHOTOMETRIC CHARACTERISTICS AND METHODS AND MEANS OF THEIR CONTROL UNDER THE CONDITIONS OF OPERATION

A brief overview of the features and possibilities of innovative technologies in the field of front light-ing systems of mechanical vehicles, in particular, adaptive front lighting systems, intelligent front lighting sys-tems and modern digital lighting systems, was conducted. The main features of the structure and operation of such systems are considered, and some characteristics and capabilities of the front lighting systems used in Mercedes-Benz cars are given. Analyzed the requirements of the UNECE Rules and state standards of Ukraine in force in Ukraine with the requirements for methods and means of monitoring the conformity of installation parameters and photometric characteristics of front lighting systems during the operation of cars and the re-quirements of the manufacturer’s normative and technological documents for the performance of control, di-agnostic and regulatory maintenance work front lighting systems of Mercedes-Benz cars. The results of the work performed were used in the development of methodological instructions for the performance by NTU stu-dents of laboratory work on maintenance and inspection of the condition and adjustments of Mercedes-Benz headlights. Based on the results of the research, proposals and recommendations have been developed regard-ing the expediency of making changes to the state standards and regulatory documents in force in Ukraine, which regulate the performance of works to control the compliance of the technical condition of mechanical road vehicles with safety requirements in terms of external lighting devices. Also, recommendations have been developed for the use of control and diagnostic equipment, with which it is advisable to equip posts for mainte-nance of external light devices of Mercedes-Benz cars by maintenance stations located in Ukraine. Keywords: car headlight, adaptive front lighting system, intelligent front lighting system, digital lighting sys-tem, dynamic cornering lighting, static cornering lighting, low beam headlights, high beam headlights, adaptive low beam, adaptive high beam, city light mode, extra-urban mode light, light mode on highways; advanced fog light mode, fog light, matrix LED light, light with micro-opto-electromechanical system.

Review Paper on Street Light Automatic Intensity Controller

Abstract: This paper is planned for making more secure roadways with canny light framework to lessen power utilization. This framework has programmed road light power control dependent on the vehicular development and turning ON and OFF of road lights relying upon the light atmosphere. This will help in decreasing the power utilization during long periods of small street use. The road light module is introduced subsequently for each specific separation. This paper additionally targets lessening street mishaps by recognizing utilization of liquor by the driver. This can be actualized utilizing liquor sensor module which contains skin sensor, breath liquor sensor and nearness sensor. The skin sensor and broadness liquor sensor distinguish the nearness of liquor content and the nearness sensor helps in identifying any sort of misbehaviour. The oddity of this paper is to successfully lessen the vitality utilization of the road lights by controlling the road light's force, detecting both human just as vehicular development and injury and passing brought about by alcoholic driving can be forestalled by earlier detecting of the liquor content in drivers by a basic and affordable way..

The Impact of Temporal Light Modulation on Psychological Responses Assessed by the Stroboscopic Visibility Measure

ABSTRACT With the advent of LED lighting systems, short-term psychological responses to temporal light modulation (TLM) in offices have attracted considerable research attention in recent years. The stroboscopic visibility measure (SVM) is a leading metric for predicting the visibility of stroboscopic effects, one of visual perception effects of TLM. However, research is lacking to link TLM with potential psychological responses using the SVM metric. In this study, 10 participants joined in the experiments under 6 SVM levels (SVM: ~0.060; ~0.500; ~1.000; ~1.500; ~2.500; ~3.868) finishing tasks of subjective general rating, moving objects observation, sustained attention visual task, visual fatigue scale and PANAS (Positive and Negative Affect Scales). This study found that the SVM metric significantly evaluated the impact of TLM on psychological responses related to lighting ambiance and the moving objects observation. As expected, the stroboscopic visibility and motion dispersion scores increased with increasing SVM levels in the observation of rotating disc, and detectable stroboscopic effects were found to have negative effects on visual and work performances. However, the results of sustained attention visual task indicated that the SVM metric performed poorly in predicting the effects of TLM related to the eye saccades. High SVM levels were associated with negative experiences of lighting coziness, cognition performance and stroboscopic perception during moving objects observation. The scores were close to the expected at ~ 1.000 but exhibited a non-linearly increase with higher SVM levels. This study contributes valuable data to the ongoing discussions on setting limits for allowable modulation in practical lighting applications.

Generating multiple polarization outputs using random binary patterns with cascaded spatial light modulators

Generating multiple polarization outputs using random binary patterns with cascaded spatial light modulators

Enhancing multi-plane light conversion orbital angular momentum multiplexer performance via error analysis.

We present what we believe to be a novel orbital angular momentum (OAM) multiplexing apparatus capable of handling topological charges ranging from l = 0 to ±3 through multi-plane light conversion (MPLC) across four phase planes. Nevertheless, the fabricating process of MPLC devices is prone to errors that cannot be avoided. Our investigation primarily delves into the repercussions of misalignment and etching inaccuracies on the device's phase, with the assistance of a spatial light modulator. The scrutiny of fabrication errors associated with the device offers valuable insights for refining the fabricating of MPLC devices. The OAM multiplexing device converts the phase of MPLC onto a glass substrate through four etching steps, corresponding to a depth of 0-775 nm. OAM multiplexing/demultiplexing crosstalk based on MPLC is less than -20 dB and -18 dB, respectively. The insertion loss of the OAM mode generated by the OAM multiplexing device coupled to the few-mode fiber is less than 7 dB. In a communication experiment, we demonstrated multiplexed three OAM channels carrying 10 Gbit/s OOK signals over a 5 km few-mode fiber using two MPLC devices. Both the bit error rate curve and constellation diagram demonstrate the excellent performance of MPLC-based OAM multiplexing devices in communication networks.

Analysis of Factors Influencing the Generation of a Higher-Order Hermite–Gaussian Mode Based on Cascaded Spatial Light Modulators

Analysis of Factors Influencing the Generation of a Higher-Order Hermite–Gaussian Mode Based on Cascaded Spatial Light Modulators

Non-mechanical steering of the optical beam in spectral-domain optical coherence tomography

We demonstrate in a proof-of-concept experiment spectral-domain optical coherence tomography where steering of the optical beam that probes the sample in a transverse scan does not make use of any mechanical element. Steering is done with the help of a phase-only spatial light modulator, that introduces a spatially-dependent phase between the two orthogonal polarization components of an optical beam, and some optical elements that control the polarization of light. We demonstrate that making use of the non-mechanical beam steering system considered here, we can reproduce the main traits of imaging with standard OCT that makes use of mechanical-assisted optical beam steering.

Multiple Fano Resonances Enabled by the Interference between an Out‐of‐Plane Plasmon Mode and Fabry–Pérot Cavity Modes

AbstractMultiple Fano resonances (mFRs) are arising as a promising optical platform to achieve precise sensing and detection. However, experimentally achieving mFRs by simple structures has remained challenging, which impedes the widespread applications of mFRs. Herein a simple structure composed of a single colloidal metal nanoparticle and a transition metal dichalcogenide flake to simultaneously achieve up to 8 FRs in experiments is demonstrated. Combining theoretical and experimental techniques, that an out‐of‐plane plasmon mode of the metal nanoparticle interferes with the Fabry–Pérot cavity modes from the WS2 flake to form mFRs in the visible region is proved. The simplicity and generality of the method further allow us to systematically study the tunability of the mFRs, in terms of the peak/dip positions and the number of FRs, by changing the structural parameters, which include the thickness of the WS2 flake, size and shape of the plasmonic nanoparticle. In addition, the quality of the mFRs is proved to be adjustable by tuning the reflectivity of the substrate in the system. The highest quality factor and spectral contrast of the achieved resonances are up to ≈180 and ≈0.95, respectively. The simple structure and high‐quality optical modes will prosper applications in precise sensing and light modulation.

A flare removal network for night vision perception: Resistant to the interference of complex light

AbstractThe high‐precision visual perception results are easily affected by the lens flare issue when the image sensor is facing to strong light. The existing flare removal methods have poor robustness when confronted with flare interference caused by complex nighttime lighting, which has to preserve natural light source information. A simulated dataset for the removal of night flares is created to solve the problem of collecting complete paired training data, and night flare removal network (NFR‐Net) is proposed to remove the interference caused by various light disturbances at night. The light source extraction module is introduced to retain light source information realistically and effectively in night vision scenes. Extensive experimental results demonstrate that the proposed method is superior to the existing related methods in the various complex night vision scenes. The proposed NFR‐Net can enhance visual perception of nighttime images significantly and improve the performance of night vision tasks.

A dynamic beam switching metasurface based on angular mode-hopping effect

Fast and versatile beam forming and steering technologies are now crucial for various emerging applications, including wireless optical communications and optical switches. However, these technologies often rely on expensive components, such as spatial light modulators (SLMs) and optical phase arrays (OPAs), which come with complex and power-consuming control systems. In response to this challenge, we propose a dynamic beam-switching method inspired by the mode-hopping effect of lasers. As a proof of concept, we introduce the dynamic beam switching metasurface (DBSM) design, featuring an in-plane mechanical actuation system. Our numerical analyses, based on the finite element method (FEM), demonstrate that the proposed DBSM exhibits versatile beam forming and steering functionalities. These include beam splitting and omnidirectional beam steering. Moreover, we anticipate that the tuning speed of the DBSM will reach the kilohertz (kHz) range or even higher when utilizing a microelectromechanical systems (MEMS) actuator, building upon pioneering research in this field. We envision it holds promising applications in areas such as light detection and ranging (LiDAR), optical wireless communication devices, and optical switches.

Quartz Enhanced Photoacoustic Spectroscopy on Solid Samples.

Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS) is a technique in which the sound wave is detected by a quartz tuning fork (QTF). It enables particularly high specificity with respect to the excitation frequency and is well known for an extraordinarily sensitive analysis of gaseous samples. We have developed the first photoacoustic (PA) cell for QEPAS on solid samples. Periodic heating of the sample is excited by modulated light from an interband cascade laser (ICL) in the infrared region. The cell represents a half-open cylinder that exhibits an acoustical resonance frequency equal to that of the QTF and, therefore, additionally amplifies the PA signal. The antinode of the sound pressure of the first longitudinal overtone can be accessed by the sound detector. A 3D finite element (FE) simulation confirms the optimal dimensions of the new cylindrical cell with the given QTF resonance frequency. An experimental verification is performed with an ultrasound micro-electromechanical system (MEMS) microphone. The presented frequency-dependent QEPAS measurement exhibits a low noise signal with a high-quality factor. The QEPAS-based investigation of three different solid synthetics resulted in a linearly dependent signal with respect to the absorption.

Image optimization of a computer-generated hologram by reusing zero-order beams and reflectors vibration.

In computer-generated holography, spatial light modulators are predominantly used for image reconstruction. However, the quality of the reconstructed images is often compromised by laser speckle and zero-order light diffraction. To address these problems, we propose the reuse of the zero-order beam, which not only eliminates the interference caused by zero-order diffraction in the reconstructed images but also considerably enhances image brightness. Moreover, we propose the use of vibrating reflectors in the proposed structure for reusing the zero-order beam to reduce speckle, thereby suppressing the speckle contrast in reconstructed images to less than 4%.

Simplifying tailored generation of complex structured femtosecond pulses with easily fabricated phase plates.

This article presents a novel approach to targeted 4f pulse shaping using phase plates fabricated by single-point diamond turning (SPDT) machining. The manufacturing of the phase plates using SPDT is versatile, cost-effective, fast, robust, and applicable across a wide range of optical materials, spanning from visible to far-infrared spectra (e.g., PMMA, ZnSe). Manufactured profiles can be used for phase manipulation and pulse structuring, analogously to programable spatial light modulators (SLM). We demonstrate that the pulse waveforms can be reproduced with high fidelity by simple simulations based on calculating optical path differences induced by the phase plate for each wavelength and taking into account the finite focal spot. The simulated and reconstructed frequency-resolved optical gating spectrograms featured G errors between 1-2% and intensity errors between 0.02-0.06. Even for complex structured pulses with the rms value of the time-bandwidth product reaching 12, our method maintains high precision, in some cases even reaching lower G error compared to simpler waveforms. Finally, we also show that the phase plate can be used to attain a set of uncorrelated pulse waveforms by moving the plate relatively to the dispersed laser spectrum. Overall, this approach bypasses common limitations associated with pulse shaping using SLMs, such as pixelation, pixel cross-talk, and spectral or laser fluences constraints.

Reducing beam tracking complexity using a phase ramp and Fresnel lens when steering beams using spatial light modulators.

Steering multiple laser beams using spatial light modulators (SLMs) creates unwanted diffraction and reflections that are not modulated by the SLM, which can make beam tracking difficult. A novel, to the best of our knowledge, and simple beam steering methodology is proposed, which aims at reducing the influence of this clutter while maintaining tracking performance. The beam(s) are deliberately defocused before steering with a superposition of a phase ramp and Fresnel lens (PRFL) phase screen on the SLM. As a result, the non-modulated reflections and diffracted light are decreased in relative intensity to the steered beam, in turn allowing simple and standard peak intensity and center of gravity (CG) algorithms for tracking. Hardware demonstration shows tracking performance using the PRFL remained on-par with more complex filtering approaches while adding no additional hardware. This method has potential to improve the communication performance of multi-beam laser communication terminals.

Rotation of liquid crystal microdroplets in the intensity minima of an optical vortex beam.

An optical vortex is characterized by its donut-shaped intensity distribution and helical phase structure. In this study, we demonstrate that an optical vortex beam, generated by a spatial light modulator, can trap, circulate, and rotate liquid crystal microdroplets of various sizes at different positions within the beam. Our findings indicate that larger microdroplets are trapped at intensity minima without altering their internal liquid crystal orientation, which is fluid by nature, and the rotation of microdroplets were observed. This rotation, a rare phenomenon, occurs without damaging or altering the inner liquid crystal molecules, offering an advantage over traditional circularly polarized optical trapping, which can generally alter inner molecular arrangements of liquid crystal. This report details the relationship between trapped particle size, trapping position, and rotation angle of liquid crystal microdroplets within an optical vortex beam.

Eyebox expansion of a lensless near-eye display using diverging spherical wave illumination and a multiplexed holographic optical element

We expand the eyebox size of a lensless holographic near-eye-display (NED) using passive eyebox replication technique that incorporates a spatial light modulator (SLM) and a holographic optical element (HOE). In holographic NEDs, the space-bandwidth product (SBP) of the SLM determines the exit pupil dimensions and corresponding eyebox size. The base eyebox size is replicated in the horizontal direction by using the horizontal high-order diffractions of an SLM under spherical wave illumination and a multiplexed HOE combiner. When a digital blazed grating and a digital lens phase are added to the computed phase hologram sent to the SLM, two spatially separated, horizontal high-order diffraction terms with identical intensity and information can be uniformly formed without the zero-order term. When the eyebox size is expanded, the field-of-view (FOV) is not sacrificed; spherical divergence wave illumination alleviates the need for a tradeoff between FOV and eyebox size. The astigmatism introduced during HOE fabrication is counterbalanced by pre-correcting the target image using a computer-generated, holographic computation algorithm. The prototype system shows simple and effective, distortion-free eyebox expansion of a wide-angle, lensless, holographic NED.

African swine fever virus structural protein p17 inhibits IRF3 activation by recruiting host protein PR65A and inducing apoptotic degradation of STING.

African swine fever virus (ASFV) is notoriously known for evolving strategies to modulate IFN signaling. Despite lots of efforts, the underlying mechanisms have remained incompletely understood. This study concerns the regulatory role of viral inner membrane protein p17. We found that the ASFV p17 shows a preferential interaction with cGAS-STING-IRF3 pathway, but not the RIG-I-MAVS-NF-κB signaling, and can inhibit both poly(I:C)- and poly(A:T)-induced activation of IRF3, leading to attenuation of IFN-β induction. Mechanistically, p17 interacts with STING and IRF3 and recruits host scaffold protein PR65A, a subunit of cellular phosphatase PP2A, to down-regulate the level of p-IRF3. Also, p17 targets STING for partial degradation via induction of cellular apoptosis that consequently inhibits activation of both p-TBK1 and p-IRF3. Thus, our findings reveal novel regulatory mechanisms for p17 modulation of IFN signaling and shed light on the intricate interplay between ASFV proteins and host immunity.

Image authentication with exclusive-OR operated optical vortices

Optical vortices carrying orbital angular momentum have drawn much attention because they provide high-dimensional encoding. Employing an array of optical vortices, we demonstrate an authentication verification system. For security authentication, an exclusive-OR logic operation has been implemented employing a light beam consisting of an array of vortices. A liquid crystal spatial light modulator has been used to generate orthogonal states of optical vortices. The proposed technique can provide a secure method of authentication with straightforward implementation. We have presented simulation and experimental results to verify the proposed scheme.

Optimal design of multilayer optical thin film structure for smart energy saving applications using needle optimization approach

In this work, a novel design of a one dimensional photonic crystal (1D PC) is investigated. The 1DPC structure is composed of alternating layers of tantalum pentoxide (Ta2O5) and silicon dioxide (Sio2). The proposed 1D PC structure is designed to act as short wave pass (SWP) edge filter that selectively passes light of short wavelengths, while the infrared light is blocked. In this study, Essential Macleod software is used to create the optimal design with the computational support of the needle synthesis technique. By varying the incidence angle of the mean polarized light mode, we can determine the features of the optimal SWP edge filter design, which leads to an important application for this filter. It can shed light on the filter’s suitability as a smart energy saving window coating for hot climate regions. The study includes different hot regions in Saudi Arabia such as Mecca, Riyadh, Dammam, Arar and Alaqiq. They were used as case studies in this research. According to the study of the optimal design of SWP edge filter applied in Mecca, Riyadh, Dammam, Arar and Alaqiq provinces, the light transmittance in the visible region is more than 99% during the summer solstice and more than 96% during the winter solstice. The photonic band gab (PBG) is almost constant during the summer solstice without shifting or decreasing in size whereas in the winter solstice, the PBG shifts toward the short wavelengths and decreases in size by increasing the angle of incidence. This allows an amount of solar energy to enter in winter. Riyadh, Dammam, and Arar provinces experienced a significant increase in solar energy during the winter solstice, more than Mecca and Alaqiq provinces.