Single Optical System Research Articles

A fiber-wireless integration approach in WDM-PON architecture, boosted with polarization multiplexing and optical frequency comb source

Abstract The paper discusses an optical frequency comb source (OMCG)-enabled hybrid single mode fiber (SMF) and free space optical (FSO) communication system (fiber-wireless) delivering a total capacity of 96 Gbps by incorporating polarization division multiplexing (PDM) in passive optical network (PON) architecture. For the accomplishment of PDM, three diverse states of polarization (SOPs) are explored such as 00, 450, and 900. Performance investigation of proposed system is conducted for assessing Q factor and BER by exploring the different modulation formats in proposed system such as modified duo-binary return to zero (MDRZ), return to zero (RZ), compressed spectrum RZ (CSRZ), and non-RZ (NRZ). Results revealed that presented design can cover 30 km SMF + 3.4 km FSO range by incorporating MDRZ due to its spectral efficient and dispersion tolerant properties.

Fractioned-pattern radiation mapping, Part II: assessment

In Part I, the authors proposed a theoretical background for predicting the radiation distribution in any optical system based on decomposing the emitting source power. Here, we describe the validity of this decomposition through a practical example that uses a radiating source and a single surface optical system. This source is calibrated in a metrology testbed that guarantees its traceability to the candela (cd), the International System (SI) base unit for luminous intensity I v . A second example, this time numerical, shows the method’s performance in a multisurface optical system.

Motion-artifact-free single shot two-beam optical coherence elastography system.

The assessment of the biomechanical properties of the skin using various imaging techniques has been used as a diagnostic tool in dermatology. Optical coherence elastography (OCE) is one of the techniques that allows for the measurement of elastic properties. OCE relies on measuring tissue displacements induced by external sources. Measuring the tissue's mechanical properties in vivo using OCE is often challenging due to bulk tissue movement. This study aimed to develop an OCE system that allows for minimizing the effects of bulk tissue movements. To achieve this, we designed a two-beam OCE system that simultaneously measures the tissue displacement at two locations on the sample. This allows for cancelling the effect of the tissue bulk movement, which is common to both measurement points. We used a piezoelectric transducer to generate surface acoustic waves (SAW) in the sample. The velocity of the excited waves, which is proportional to the rigidity of the sample, was measured by calculating the phase delay of the SAW at two locations on the sample. Simultaneous measurement at two locations was achieved by dividing a single light beam into two by focusing on the sample at two different locations. The two beams travel different optical path lengths, and the reflected signals were depth encoded in a single optical coherence tomography scan using a single reference beam. The system was characterized using different tissue-mimicking phantoms and the skin of healthy volunteers at the wrist and the palm. We achieved an approximately 50-fold increase in phase sensitivity measurement. We designed a simple two-beam OCE system that effectively minimizes the effect of tissue movement. We believe that the presented system will find immediate applications in the clinic to monitor the progression of systemic sclerosis disease.

Synthetic aperture optical image restoration based on multi-scale feature enhancement

With the wide applications of high-resolution imaging technology in topographic mapping, astronomical observation, and military reconnaissance and other fields, the requirements for imaging resolution of optical system are becoming higher and higher . According to the diffraction limit and Rayleigh criterion, the imaging resolution of the optical system is proportional to the size of the aperture of the system, but affected by the material and the processing of the optical component: the single aperture of the optical system cannot be infinitely enlarged. Therefore the synthetic aperture technology is proposed to replace the single large aperture optical system. Owing to the effect of sub-aperture arrangement and light scattering, the imaging of synthetic aperture optical system will be degraded because of insufficient light area and phase distortion. The traditional imaging restoration algorithm of synthetic aperture optical system is sensitive to noise, overly relies on degraded model, requires a lot of manually designed models, and has poor adaptability. To solve this problem, a multi-scale feature enhancement method of restoring the synthetic aperture optical image is proposed in this work. U-Net is used to obtain multi-scale feature, and self-attention in mixed domain is used to improve the ability of of the network to extract the features in space and channel. Multi-scale feature fusion module and feature enhancement module are constructed to fuse the information between features on different scales. The information interaction mode of the codec layer is optimized, the attention of the whole network to the real structure of the original image is enhanced, and the artifact interference caused by ringing is avoided in the process of restoration. The final experimental results are 1.51%, 4.42% and 5.22% higher than those from the advanced deep learning algorithms in the evaluation indexes of peak signal-to-noise ratio, structural similarity and perceived similarity, respectively. In addition, the method presented in this work has a good restoration effect on the degraded images to different degrees of synthetic aperture, and can effectively restore the degraded images and the images with abnormal light, so as to solve the problem of imaging degradation of synthetic aperture optical system. The feasibility of deep learning method in synthetic aperture optical image restoration is proved.

Importance of cultural values in the development of tourism in the kyzylorda region

This article analyzes the development of cultural tourism in Kyzylorda region. In the analysis of the situation of cultural tourism in Kyzylorda region, the presentation of tourist attractions in a single optical system was considered as the main element. The integrity of the meta-image of the region taken as an object of study consists of ordering the textual narration and their symbolic coordination.The methodological basis is derived from determining the internal connection of the logical and historical analysis of the cultural content of the Kyzylorda region, in the process of explaining the cultural symbols, special attention is paid to the integrity of the national identity.Here, the semiotic dimension can model the configuration of metastructures, allowing them to become an attractive object of interest to tourists. The use of the method of semiotization of tourist objects gives quick results in determining the interaction of symbolic views, in the process of introducing the visual contours of the region, landmarks to tourists. The results of this can serve as a basis for the development of cultural tourism in the Kyzylorda region. Modern definitions of the concepts of «cultural branding», «regional brand», «regional brand» have been given importance from the point of view of cultural studies and their content has been explained.

An All-Day Attitude Sensor Integrating Stars and Sun Measurement Based on Extended Pixel Response of CMOS APS Imager

For celestial measurement, it is difficult to enable a single optical system to image and measure both stars and the sun due to vastly different light intensity of targets and limited response capability of the image sensor pixel. Here, we develop an all-day optical attitude sensor integrating stars and the sun measurement based on extended pixel response model of the CMOS APS (Active-pixel sensor) imager. For extremely large light intensity, we extend the conventional pixel response model to the oversaturated stage where the pixel values reverse and drop below the saturation value. Based on this, the integration of the star sensor and the sun sensor is realized. The pixels image the starry sky with linear response, and make use of the oversaturation response to image the sun and obtain a black spot on the bright background. This principle enables the capability of all-day high-precision attitude measurement using a single miniaturized sensor. An integrated optical attitude sensor is designed and manufactured. Ground-based observation results show that the orientation accuracy from sun measurement is better than 9" (3σ), and the attitude accuracy from star measurement is better than 5" (3σ) for pointing and 11" (3σ) for rolling. The sensor can be applied to high-precision all-day navigation systems for miniaturized spacecrafts and aircrafts.

Trapped-mode excitation in all-dielectric metamaterials with loss and gain

Non-Hermitian photonics based on combining loss and gain media within a single optical system provides a number of approaches to control and generate the flow of light. In this paper, we show that by introducing non-Hermitian perturbation into the system with loss and gain constituents, the high-quality resonances known as trapped modes can be excited without the need to change the symmetry of the unit cell geometry. To demonstrate this idea, we consider a widely used all-dielectric planar metamaterial whose unit cell consists of a pair of rectangular nanoantennas made of ordinal (with loss) and doped (with gain) silicon. Since the quality factor of the trapped-mode resonance can be controlled by changing both spatial symmetry and non-Hermiticity, varying loss and gain allows us to compensate for the influence of asymmetry and restore the quality factor of the localized mode. The results obtained suggest new ways to achieve high-quality resonances in non-Hermitian metamaterials promising for many practical applications in nanophotonics.

Comparison of Passive and Active Fiducials for Optical Tracking

Abstract The paper analyses the constraints related to optical tracking of an HMD with a single commercial binocular stereoscopic optical tracking system and offers an overview of different factors affecting the best active fiducial set-up and marker geometries for reliable tracking with a focus on the rotational accuracy of a marker. Two IR diode models with different emission characteristics were tested as active fiducials and the results were compared to localization accuracy of passive fiducials. In terms of preferable marker geometry, it was found that the area enclosed by the fiducials should be maximized. Thus, due to geometrical constraints, very small marker geometries may not be stable or feasible entirely. Rotational accuracy was analysed for cases when the marker was not directly facing the tracking device and it was found that rotation about one axis introduced errors to the determined orientation in space related to the other axes as well.

“Design and building of a high speed Schmidt-Cassegrain objective for space qualified remote sensing camera”

Remote sensing satellites require very accurate pointing to specific locations of interest with high resolution and small latency. Therefore, the space imaging systems attempted to achieve the possible highest ground resolution with minimum cost as possible. In this paper, design process of an electro-optical imaging payload is described considering the limited weight and small volume in addition to minimum power consumptions. The most promising prospects for high resolution imaging are connected with passive optical sub-systems, especially push broom one. For design a multiband Space remote sensing payload with 4°7′ field of view that operates in multi spectral bands and a panchromatic band, it requires the high speed Schmidt–cassegrain objective. The most promising prospects for high resolution imaging are connected with passive optical sub-systems, especially push broom one. The Schmidt-Cassegrain objective is a catadioptric objective that combines a Cassegrain reflector’s optical path with a Schmidt corrector plate to make a compact objective that uses simple spherical surfaces only. Because of the limited weight of the camera (22.2 kg), the multispectral consists of only one single optical system large F-Number (F5) and provided with spectrum splitter.In addition, the key points in design of such types of cameras were listed as well as clarifying the optical design of such objective.

Relationship between Standing Trunk Extension Angle and Medial Elbow Injuries in Young Baseball Pitchers.

Purpose: The purpose of this study was to investigate the relationship between the standing trunk extension angle and medial elbow injuries. Subjects and methods: The study participants were 90 male baseball pitchers (10–12 years) belonging to youth baseball teams. Pitching elbow injuries were evaluated by an orthopedic surgeon using ultrasound scans and physical examination findings. A single optical three-dimensional motion analysis system was used for the trunk extension measurements, with three-dimensional coordinates captured. The overall, upper, and lower trunk angles were then analyzed. Results: Trunk extension angle during standing trunk extension was significantly smaller among participants who were positive for medial elbow injuries on ultrasound scans (positive: 71.4° ± 10.3°; negative: 75.7° ± 9.2°; t = 2.05, p < 0.05). The upper trunk extension angle was significantly smaller than the lower trunk extension angle among participants who were positive for medial elbow injuries on physical examination (upper: 33.0° ± 6.9°; lower: 41.2° ± 8.2°; t = −2.42, p < 0.05). Conclusions: Trunk extension angle during standing trunk extension is associated with medial elbow injuries. Evaluating the trunk extension angle as multiple segments rather than a single rigid body is valuable.

Calibration of single optical wedge compensation test system error by computer generation hologram

The predecessor of China Optics was China Optics and Applied Optics Digest, which was founded in 1985. At that time, it was the only retrieval journal in the field of optics in China. At the end of 2008, China Optics and Applied Optics Digest was renamed

Multipoint Bending Measurement Using Multicore Fiber Bragg Grating and Two-Photon Absorption Process in Si-APD

We propose and demonstrate a fiber optic multi-point bending measurement system that uses Bragg gratings inscribed along a multi-core fiber (MCF) and a silicon avalanche photodiode (Si-APD) that produces two-photon absorption (TPA) photocurrent for 1.55- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> light. Because the TPA photocurrent from the Si-APD is proportional to the mean square of the optical intensity, the intensity correlation between 1.55- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> probe and reference beams is measured from it without using complex electrical circuits. The proposed system has different lengths of optical fibers between each core of MCF and input/output ends of a single mode fiber optic system, which makes different the correlation signal between the reference beam and the probe beam reflected from different Bragg gratings in MCF. That enables the reflection spectra of all the Bragg gratings in MCF to be separately measured even when they are overlapped in the wavelength domain. As a result, the bending radius and its direction are measured without using multiple detectors or optical switching devices. We conducted proof-of-concept experiments by using a 7-core MCF with almost the same Bragg gratings inscribed in each core at three points along the fiber. We also demonstrated an example of application to shape measurement.

Performance comparison of dispersion compensation using EDC at distinct data rates with distinct photo-detectors devices at receiver

The transmission of the high data rate and information over the optical fiber is restricted by various dispersion phenomenon which further results into inter-symbol interference (ISI). There are numerous alternatives present to resolve this hurdle of dispersion. Unlike other dispersion compensating procedures, electronic dispersion compensators (EDC) which makes use of non-linear and linear equalization approach is an effectual, cost effective and compact dispersion compensating method. This paper is approaching EDC technique for compensation of chromatic dispersion at four distinct bit rates of 25, 30, 40 and 40 Gbps over 120Km of single mode fiber. To Achieve this, a single channel optical system with the help of simulation software i.e., Optisystem is being used for the above-mentioned technique. After exploring their outcomes, another operation of comparing these two-bit rates using pin photodiode and avalanche photodiode has been applied. The simulations showed the optimum photodiode for efficacious dispersion compensation at such a long transmission distance.

Curved Sensors for compact and high-performance imaging systems

Curved sensors enable a substantial simplification of optical systems and significant improvement of the image quality. Both lead to the reduction of the mass-volume budget of the instruments, simplify the manufacturing and shrink the integration time, resulting in a drop of the consolidated cost. The field curvature is an optical aberration describing the light going through an imager and producing an image on a portion of a sphere. This aberration is present in every single optical system and particularly in wide-angle imaging. Current solutions applied to correct the images imply the complexification of the instruments by using field flatteners, ie. more optics of complex shape, thus increasing the mass-volume and cost budget. The use of curved sensors helps overcoming these issues. It corrects the field curvature directly at the focal surface. For 10 years, the CNRS-LAM demonstrated, through theoretical studies and prototyping, that the use of curved sensors allows to remove 30 to 50 percent of the lenses count and drastically releases constraints in optical systems. I am currently leading a parametric study regarding the contribution of curved sensors for UV imaging system. This study is done through an imager aiming at observing aurora with a wide field of view (more than 60 degrees) in 130-138nm bandwidth with a signal to noise ratio higher than 10. The first main constraint in this project is to get a high transmissive system in FUV bandwidth. To address this problematic, the number of lenses must be reduced. However, reducing the number of lenses means reducing the number of degrees of freedom to correct the aberrations of such a wide field system. To maintain high optical performance, I have considered the use of curved and freeform sensors to correct the field curvature and astigmatism directly in focal surface. In this talk I will present the parametric study I have been leading on the design of this FUV imager. I will quantify the benefits of using curved and freeform sensors compared to flat sensor to keep high performance whilst reducing the number of lenses from 6 to 3 to increase the throughput by a factor 3.

Human–machine interaction control for stochastic cell manipulation systems

While many physical robot systems are able to work cooperatively with humans to perform numerous tasks, existing optical cell manipulation systems can only perform either manual or automated tasks at a time. As optical cell manipulation is essentially different from robotic manipulation in the physical world due to its stochastic nature, existing human–robot interaction control techniques cannot thus be directly reproduced into optical micro-manipulation of cells. This paper proposes a human–machine interaction control approach for stochastic optical cell manipulation systems. A theoretical foundation is then developed, and thus enabling human to interpose or interact, when applicable or needed, with an automated cell manipulation system without interrupting the manipulation process. Therefore, it offers an opportunity for human to get involved with an automated cell manipulation system so as to deal with unexpected events or complex tasks, rather than to stop or restart the whole manipulation process. Both the capacity of an automated control system – which provides precise and productive cell manipulation, and human ability – in terms of decision making, if needed, are then consolidated into a single optical cell manipulation system. Rigorous mathematical formulation is developed with the consideration of the stochastic perturbations, and the stability of the human–machine interaction control system is analyzed from a stochastic perspective. Experiments are then performed to illustrate the effectiveness of the proposed approach.

Performance Analysis of All-optical PPM-mQAM Communication Systems

Increasing the spectral efficiency of transmission has increased interests in hybrid optical communication systems. However, these systems suffer from the nonlinear fiber impairments that produce nonlinear phase noise (NPN). In this paper, we investigate all-optical coding m-ary quadrature amplitude modulation (mQAM) by pulse position modulation (PPM) in a single channel optical communication system to increase the transmission capacity and reduce the NPN. The system performance that optically modulates the data by hybrid PPM-mQAM format is numerically investigated by simulation. The results show that the transmission capacity is duplicated and NPN is significantly moderated when PPM-4QAM and PPM-16QAM are used. At bit error rate (BER) of 10−4, the transmission distances of PPM-4QAM is increased by about 33%, in comparison to 4QAM system. In addition, the required optical signal-to-noise ratios (OSNRs) for achieving BER of 1×10−4 are decreased by 4.7 dB and 7.5 dB for the PPM-4QAM and PPM-16QAM schemes, respectively.

Calibration of single optical wedge test system using computer-generated hologram

Calibration of single optical wedge test system using computer-generated hologram

The effect of modulated electric field on characteristic of SDBD‐like plasma jet for surface modification

AbstractIn this paper, the dynamics and flow behaviour of an atmospheric argon plasma jet was studied in the new nozzle structure similar to the surface dielectric barrier discharge (SDBD) using the Schlieren imaging method. The effect of plasma jet driven by repetitive high‐voltage microsecond pulses with low‐frequency sinusoidal bias was measured qualitatively in a single mirror Schlieren optical system. The enhancement of plasma jet length and cross‐section of plasma jet with surface in this condition is due to highly turbulent flow of argon plasma jet in this structure. This study revealed the important role of SDBD structure and modulated electric field on the behaviour of plasma jet in a high diameter nozzle. In practice, this technique allows us to increase the jet length of the nozzle output to 5 cm and under these conditions, the diameter of the plasma jet cross‐section is increased to 8 mm, without increasing the electrical power consumption. Eventually, the hydrophilicity of the surface is also measured by the contact angle of a water droplet that decreases from 78° to 8° after surface treatment, implying we were able to reach a super‐hydrophilic surface with this plasma jet structure.

Performance Investigation of Different Dispersion Compensation Methods in Optical Fiber Communication

In optical fiber Communication system dispersion compensation has become one of the major topics of importance and research nowadays. This is because any presence of dispersion might leads to pulse spreading which might cause inters symbolic interference (ISI) and which leads to signal degradation. In this paper six different model are considered for dispersion compensation. Dispersion compensation fiber (DCF) is used to design first three models by using its three different configurations of pre-compensation, post-compensation, symmetrical compensation and Fiber Bragg Gratings (FBG), uniform FBG, IDCFBG are used for designing rest of three dispersion compensation models. Single channel optical system length of 100 km with data rate of 2.5 Gbps and 10 Gbps is used to design each model and is simulated by using optisystem software package. All the designs are compared with respect to the quality factor (Q-factor) and bit error rate (BER). With the outcome of the simulations results it is seen that post–compensation DCF model is the promising approach.

High-Resolution Hyperspectral Microscopic Imaging With Single Acousto-Optic Tunable Filter Based on Double Filtering

Hyperspectral imaging is a technique that integrates multiple spectral bands and image information. Its applications range from improving the accuracy of cancer diagnosis to testing the quality of products. Here, we introduce a double-filtering technique that provides high-resolution diagnostic histological images within minutes. The hyperspectral microscopic imaging system is built based on an acousto-optic tunable filter (AOTF). The optimized system is analyzed from the perspective of spectrum and imaging. The spectral resolution can be improved by 37.08 % to 59.95% in the visible light range. The side lobe is obviously inhibited and the purity of spectrum is improved. Furthermore, the example of hyperspectral microscopic imaging is demonstrated with unstained gastric cancer tissue sections to assess the ability of the system in terms of its spectral performances and image quality. The microscopic imaging results of single filtering optical path system and single crystal double filtering optical path system are compared. In general, the optimized double filtering system achieves excellent performance in bandwidth compression and side lobe suppression, especially the first application of hyperspectral microscopy combined with microscope in the visible light range.