Parallel Light Research Articles

Pixel-addressable phase calibration of spatial light modulators: a common-path phase-shifting interferometric microscopy approach

As spatial light modulators (SLMs) are becoming flexible and the preferred device for light steering, the SLM’s modulation calibration still remains challenging. No pixel-addressable measurement of the SLM has yet been practically implemented. We present a quantitative phase measurement and calibration method for a parallel aligned liquid crystal spatial light modulator (PAL-SLM) based on Pancharatnam phase-shifting interferometric microscopy. The pixel-wise phase of SLM can be detected from microscopic interference pattern formed from two orthogonally polarized light waves reflected off the PAL-SLM. The wave phase is modulated or non-modulated depending on its polarization direction parallel or orthogonal to the liquid crystal director. Owing to self-referencing common-path interferometric microscopic imaging, the proposed method is quite robust against environmental disturbance and enables a high-precision pixel-wise characterization of SLM.

Hybrid model based on energy and experimental methods for parallel hexapod-robotic light abrasive grinding operations

Automatic grinding using robot manipulators requires simultaneous control of the robot endpoint and force interaction between the robot and the constraint surface. In robotic grinding, surface quality can be increased by accurate estimation of grinding forces where significant tool and workpiece deflection occurs. The small diameter of the tool causes different behavior in the grinding process in comparison with the tools that are used by universal grinding machines. In this study, we develop a robotic surface grinding force model to predict the normal and tangential grinding forces. A physical model is used based on chip formation energy and sliding energy. To improve the model for robotic grinding operations, a refining term is added. The stiffness of the tool and setup is inherently included using penetration test results and estimating the refining term of the model. The model coefficients are calculated using a linear regression technique. The proposed model is validated by comparing model outputs with experimentally obtained data. Evaluation of the test results demonstrates the effectiveness of the proposed model in predicting surface grinding forces.

Design and Performance of a Portable and Multichannel SPR Device.

A portable multichannel surface plasmon resonance (SPR) biosensor device is presented in this study. As an optical biosensor device, the core component of its light path is a semi-cylindrical prism, which is used as the coupling unit for the excitation of the SPR phenomena. Based on this prism, a wedge-shaped incident light beam including a continuous angle range (10°) is chosen to replace the commonly-used parallel light beam in traditional SPR devices, in which the incident angle is adjusted by a sophisticated mechanical system. Thus, complicated, cumbersome, and costly mechanical structures can be avoided in this design. Furthermore, the selection of a small and high-stability semiconductor laser and matrix CCD detector as well as a microfluidic system aids in the realization of a miniaturized and multichannel device. Several different samples were used to test the performance of this new device. For ethanol with different concentrations, the sensing response was of good linear relativity with the concentration (Y = 3.17143X + 2.81518, R2 = 0.97661). Mouse IgG and goat anti-mouse IgG were used as biological samples for immunological analysis, and BSA as the control group. Good specific recognition between mouse IgG and goat anti-mouse IgG has been achieved. The detection limit of antibody to antigen coated on the sensing surface was about 25 mg/L without surface modification.

New Vision Probe Based on Telecentric Photography and Its Demonstrative Applications in a Multiphase Stirred Reactor

A new vision probe based on telecentric photography has been developed for multiphase system measurement. Four outstanding advantages of the probe are as follows: (i) Sharp pictures with little image distortion can be obtained because of the distinctive parallel light paths from the telecentric lens. (ii) The slim probe can be inserted everywhere in large reactors. (iii) Local characteristics such as particle (solid particle or drop or bubble) size, holdup, and interfacial area with one or even more dispersed phases can be measured. (iv) The higher holdup of the dispersed phase is allowed. The robustness of the probe has been tested in a multiphase reactor. Finally, applications in solid–liquid, gas–liquid, and gas–liquid–solid stirred tanks are present respectively to demonstrate the measurements on the particle holdup, bubble size, and particle and bubble size using this vision probe.

Towards a Grand Unified Theory of sports performance: A response to the commentaries

Film type panoramic aerial camera mounted on the aircraft is a fine optical instrument to photograph the ground scene, Dynamic resolution detection is an important judgment to evaluate the imaging quality when camera is in the flying situation or motion scene is imaged. According to its principle of work to design a set of indoor detection system with dynamic resolution detection. Based on the analysis of its working principle and performance index, The overall scheme of the dynamic resolution detection device is proposed. Far target simulation system-large field view parallel light pipe, dynamic graphics system and dynamic graphic generation system structure are designed in detail, Proposing the test method to core parameters of parallel light pipe and dynamic graphics generator, this detection system meet the needs of dynamic resolution detection By theoretical analysis and practical testing.

Parallel femtosecond laser light sheet micro-manufacturing based on temporal focusing

We present a parallel depth resolved laser fabrication technique for micro- and nano-machining metal substrates based on temporal focusing. In this system, the spectrum of a femtosecond laser pulse is first spatially separated by a digital micromirror device, which simultaneously serves as a diffraction grating and a programmable binary mask. After collimation and beam flattening, an objective lens recombines the spectrum to the focal region, forming a high-intensity, depth resolved light sheet for laser micromachining. The light sheet technology enables parallel fabrication of highly uniform micro-structures of close to diffraction-limited resolution. Experimental results demonstrate high-resolution (~800nm) direct area patterning on various metal substrates, e.g., nickel and copper, over an area of ~100×60µm2 within tens of laser pulses. The relationship among material removal rate, surface flatness, laser power, and number of pulses have been experimentally studied; the results suggest the application of higher power with fewer number of laser pulses produce microstructures of better surface quality. The light sheet technology substantially improves the throughput of ultrafast laser machining, enabling direct area patterning without compromising the resolution.

Effect of dividing daylight in symmetric prismatic daylight collector

This paper presented a symmetric prismatic daylight collector to collect daylight for the natural light illumination system. We analyzed the characteristics of the emerging light when the parallel light beam illuminate on the horizontally placed symmetric prismatic daylight collector. The ratio of the relative intensities of collected daylight that emerging from each surface of the daylight collector shown that the ratio is varied with the incident angle during a day. The simulation of the emerging light of the daylight collector shown that the ratio of emerging light is varied with the tilted angle when sunshine illuminated on a symmetric prismatic daylight collector which was not placed horizontally. The integration of normalized intensity is also varied with the tilted angle. The symmetric prismatic daylight collector with the benefits of reducing glare and dividing intensity of incident daylight, it is applicable to using in the natural light illumination system and hybrid system for improving the efficiency of utilizing of solar energy.

Fast flux density distribution simulation of central receiver system on GPU

The simulation of the light flux density distribution on a receiver plays an important role in energy estimation, design and optimization of a heliostat field and the focusing strategy for a central receiver system (CRS). However, this simulation is a time-consuming procedure. In this paper, we propose a fast simulation method that fully exploits the tremendous rendering and parallel computing capacities of contemporary graphics processing units (GPUs). First, an auxiliary spatial data structure is employed to organize the heliostats in the field, and a parallel light beam traversal algorithm is designed and performed on the GPU to determine the shadowing and blocking heliostats for each reference heliostat. Then, the flux spot reflected by each heliostat on the receiver is computed using the HFLCAL model and accumulated for the final flux density distribution. Both the computing stage and accumulation stage are accomplished via GPU rendering pipeline. The proposed method is verified by taking the PS10 power plant as an example. Because this method considers both shadowing and blocking effects, the simulation results are consistent with those in the official report. Due to its high efficiency, the proposed method has potential applications in CRS design and optimization.

Automatic detection of surface defects

In the automobile manufacturing industry, the detection of surface defects is a crucial process for quality control. This study simulates the process by which engineers find defects on an outer surface using a parallel light reflection map and the proposed integral reflection map (IRM)detection algorithm. This method is based on the law of reflection and reversibility of light, and detects surface defects by comparing the different behaviors of the reference model and manufactured model under reflection. Furthermore, by doing integral in valid viewpoint areas, this method avoids the instability of detection results under different viewpoint positions. Moreover, to solve the problem that the global alignment of reference and manufacture models cannot detect certain scales of surface defects, this paper proposes a local alignment method. The implementation results show that our method is highly automatic, viewpoint independent, and can detect multi-scale surface defects.

Detailed study of transient anomalous electric field vector focused by parabolic mirror

This paper provides a detailed theoretical analysis of the unexpected transient divergent and rotational distributions of the focused electric field vector reported in Shibata et al (2015 Phys. Rev. A 92 053806). We reveal the physical origin of these distributions. More quantitatively, we derive the semi-analytic expressions and clarify how these distributions depend on the mirror size, offset angle, and the intensity distribution of the incident parallel light. We compare the formulas with numerical calculations and evaluate the area where linearity holds. If the wavelength and the mirror size are sufficiently shorter than the focal length, the radius of the linear area becomes longer than the wavelength. These formulas and evaluations are useful for studies, which require high spatio-temporal resolution.

Integral three-dimensional display with high image quality using multiple flat-panel displays

We have developed a method for combining the images of multiple flat-panel displays to improve the quality of integral three-dimensional (3D) images. A multi-image combining optical system (MICOS) is used to magnify and combine the images of multiple displays without gaps between multiple active display areas. However, in the previous prototype, the image quality of the 3D images deteriorated due to the use of a MICOS that had a complicated structure and a diffuser plate. This paper describes an optical system for combining multiple images while suppressing the deterioration of 3D image quality. The improved method can suppress the deterioration of the image quality because it uses a simple structure as a MICOS and does not require a diffuser plate. Furthermore, the thickness of the entire equipment was increased because parallel light was required for the backlight of the LCD panel in the previous design. The thickness of the entire equipment could be reduced to 1/5 or less because diffused light can be used in the improved design.

Controlling light with freeform multifocal lens designed with supporting quadric method(SQM)

The SQM is a versatile methodology for designing freeform optics for irradiance redistribution. Recently it has often been applied in design of freeform lenses, mirrors and diffractive optical elements. Still, many questions regarding theory and performance of optics designed with the SQM are open. Here we investigate theoretically plano-freeform refractive lenses designed with the SQM when an incident collimated beam must be transformed into a beam illuminating with prescribed irradiances a large number of pixels on a flat screen. It is shown that a lens designed for such task with the SQM operates as a multifocal lens segmented into subapertures with focal lengths providing accurate control of the irradiance distribution between pixels. These subapertures are patches of hyperboloids of revolution. Two different designs are possible, one of which defines a concave lens. Eikonal function for such lenses is also derived. As a proof of concept, we numerically analyze performance of a plano-freeform lens designed with the SQM for transforming a uniform circular parallel light into an image of A. Einstein represented by gray values at ≈ 38K pixels.

Study on a wideband, variable aperture, high resolution scatterometer for planar diffraction grating stray light measurement.

Stray light is one of the important factors for evaluating the quality of gratings. Therefore, it has become an important problem in the field of grating development to measure the stray light of planar diffraction gratings accurately. For that reason, a planar grating stray light testing instrument based on a Czerny-Turner (C-T) structure has been studied. On the premise of the low stray light of the instrument itself, the instrument is capable of measuring wideband, variable aperture, and high resolution stray light for planar gratings. A scatterometer dynamic range of over nine orders has been demonstrated. Based on the scalar diffraction theory and classical Fresnel-Kirchhoff diffraction theory, the optical and mechanical model of the scatterometer is designed, which is irradiated by parallel light, and the simulation results are analyzed. The instrument realizes the measurement of the grating distribution function (GDF). And with reference to the expression form of the bidirectional reflectance distribution function (BRDF), the measurement data of the instrument is associated with the power spectral density (PSD). Through the optical integrated design and stray light suppression design, full aperture (15 mm×15 mm-200 mm×200 mm) and wideband (380-900 nm) measurement for any number of lines grating is realized, and the efficiency of equipment usage is improved. Experimental results show that based on the attenuation method, the accuracy of measurement can be 10-9 by the replacement of the neutral density filters.

双曲平面上非蜕化圆锥截线的聚焦性

众所周知，在平面几何中，从椭圆一个焦点出发的光线被椭圆反射后汇聚于它的另一个焦点；从双曲线的一个焦点出发的光线被双曲线反射后虚汇聚于它的另一个焦点；而对于抛物线来说，从焦点出发的光线被抛物线反射成为平行光。本文证明了双曲平面上的非蜕化圆锥截线也有相应的聚焦性；而且，存在一些非圆锥截线的曲线，它们也有聚焦性。 In the plane geometry, as we all know, the light through a focus of the ellipse is reflected by ellipse to focus on another; similarly the light through the hyperbola one focus, after reflection, reversely focuses on another; and for the parabola it is true that the light from focus is reflected into parallel light. This paper proved that the nonsingular conic curves on the hyperbolic plane have corresponding focus properties; moreover, there are some curves having focusing properties, which are not conic curves.

Self-action of Bessel wave packets in a system of coupled light guides and formation of light bullets

The self-action of two-dimensional and three-dimensional Bessel wave packets in a system of coupled light guides is considered using the discrete nonlinear Schrodinger equation. The features of the self-action of such wave fields are related to their initial strong spatial inhomogeneity. The numerical simulation shows that for the field amplitude exceeding a critical value, the development of an instability typical of a medium with the cubic nonlinearity is observed. Various regimes are studied: the self-channeling of a wave beam in one light guide at powers not strongly exceeding a critical value, the formation of the “kaleidoscopic” picture of a wave packet during the propagation of higher-power radiation along a stratified medium, the formation of light bullets during competition between self-focusing and modulation instabilities in the case of three-dimensional wave packets, etc. In the problem of laser pulse shortening, the situation is considered when the wave-field stratification in the transverse direction dominates. This process is accompanied by the self-compression of laser pulses in well enough separated light guides. The efficiency of conversion of the initial Bessel field distribution to two flying parallel light bullets is about 50%.

Three dimensional shape restoration method with parallel light interference projection

Three dimensional shape restoration method with parallel light interference projection

准平行光干涉的激光干扰方案与实验研究

A scheme for laser jamming using quasi parallel light interference was proposed. On the basis of the interference theoretical analysis, the multi -beam quasi parallel light interference images and interference intensity maximum value of two beams, three beams and four beams were obtained by HeNe laser, and the interference images and the light intensity distribution were got by simulation. Both theoretical and experimental results show that the patterns of quasi parallel light interference images depend on beam direction angle. In certain direction angle, there is bright stripes or bright spots of interference in the middle of the interference field. The distance between interference stripes or spots is decided by the angle between two beams of light. When the value of the angle between two beams is no more than 0.5 mrad, the experiment data is consistent with the simulation data, and the interference intensity maximum is close to the result of theoretical maximum, that is the light intensity maximum of two, three and four beams of quasi parallel light interference are four, eight, fifteen times the size of the light intensity of single beam. The effect evaluation and the test of validity of laser jamming scheme were given.

Design of dynamic resolution detecting device for film type panoramic aerial camera

Film type panoramic aerial camera mounted on the aircraft is a fine optical instrument to photograph the ground scene, Dynamic resolution detection is an important judgment to evaluate the imaging quality when camera is in the flying situation or motion scene is imaged. According to its principle of work to design a set of indoor detection system with dynamic resolution detection. Based on the analysis of its working principle and performance index, The overall scheme of the dynamic resolution detection device is proposed. Far target simulation system-large field view parallel light pipe, dynamic graphics system and dynamic graphic generation system structure are designed in detail, Proposing the test method to core parameters of parallel light pipe and dynamic graphics generator, this detection system meet the needs of dynamic resolution detection By theoretical analysis and practical testing.

NUCLEAR FACTOR Y, Subunit C (NF-YC) Transcription Factors Are Positive Regulators of Photomorphogenesis in Arabidopsis thaliana.

Recent reports suggest that NF-Y transcription factors are positive regulators of skotomorphogenesis in Arabidopsis thaliana. Three NF-YC genes (NF-YC3, NF-YC4, and NF-YC9) are known to have overlapping functions in photoperiod dependent flowering and previous studies demonstrated that they interact with basic leucine zipper (bZIP) transcription factors. This included ELONGATED HYPOCOTYL 5 (HY5), which has well-demonstrated roles in photomorphogenesis. Similar to hy5 mutants, we report that nf-yc3 nf-yc4 nf-yc9 triple mutants failed to inhibit hypocotyl elongation in all tested light wavelengths. Surprisingly, nf-yc3 nf-yc4 nf-yc9 hy5 mutants had synergistic defects in light perception, suggesting that NF-Ys represent a parallel light signaling pathway. As with other photomorphogenic transcription factors, nf-yc3 nf-yc4 nf-yc9 triple mutants also partially suppressed the short hypocotyl and dwarf rosette phenotypes of CONSTITUTIVE PHOTOMORPHOGENIC 1 (cop1) mutants. Thus, our data strongly suggest that NF-Y transcription factors have important roles as positive regulators of photomorphogenesis, and in conjunction with other recent reports, implies that the NF-Y are multifaceted regulators of early seedling development.

Intensity and angle-of-arrival spectra of laser light propagating through axially homogeneous buoyancy-driven turbulence.

Frequency spectra obtained from the measurements of light intensity and angle of arrival (AOA) of parallel laser light propagating through the axially homogeneous, axisymmetric buoyancy-driven turbulent flow at high Rayleigh numbers in a long (length-to-diameter ratio of about 10) vertical tube are reported. The flow is driven by an unstable density difference created across the tube ends using brine and fresh water. The highest Rayleigh number is about 8×109. The aim of the present work is to find whether the conventional Obukhov-Corrsin scaling or Bolgiano-Obukhov (BO) scaling is obtained for the intensity and AOA spectra in the case of light propagation in a buoyancy-driven turbulent medium. Theoretical relations for the frequency spectra of log amplitude and AOA fluctuations developed for homogeneous isotropic turbulent media are modified for the buoyancy-driven flow in the present case to obtain the asymptotic scalings for the high and low frequency ranges. For low frequencies, the spectra of intensity and vertical AOA fluctuations obtained from measurements follow BO scaling, while scaling for the spectra of horizontal AOA fluctuations shows a small departure from BO scaling.