This PDF file contains the front matter associated with SPIE Proceedings Volume 10787, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.

We introduce the use of an event based image sensor as a versatile device for characterisation of turbulence and for wavefront Sensing at unusually high rates. This type of sensor presents the changes in the intensity field with time that integrate to a threshold level before output, rather than the traditional integrate for a specified time period. As a result a time sequence of activity tagged to spatial location and time is provided. This information can be signal processed in novel ways to ascertain high speed imagery, or more importantly directly provide fundamental descriptors of the turbulence field related to phase structure function, and possibly determining the power spectrum parameters of Cn2 , Fried’s coherence length r0 , anisoplanatic angle and the changes in these over ensemble average timescales. The likes of the lenslet array used in Shack-Hartmann sensors can present the optical field to the sensor upon which it may provide location of the centroid by occurrence of light accumulating to a threshold, or highest temporal rate of occurrences in the region of interest behind the lenslet. In this way the Shack-Hartmann sensors it is not limited to one star per lenslet, and can respond to stationarity changes, and can facilitate investigations of chaos in the timeseries of aberrations. We explore these thoughts upon data collected on-sky from both streaming Shack-Hartmann sensor and the direct light field incident onto the sensor, and the sensor behind a lenslet array. In fact we present on-sky data from two event based sensors (ATIS and Davis 240c), alongside the traditional integration video camera. Data is acquired both with and without an image intensifier.

The atmospheric influence on wave propagation was investigated during the First European South African Transmission ExpeRiment (FESTER) from June 2015 to February 2016. The focus in this article was set on optical turbulence, the main atmospheric factor affecting the position and strength of Laser beams, the performance of electro-optical systems and imaging. Measurements were performed continuously during the campaign on three sites over the northwestern part of False Bay. The optical turbulence measurements include in situ measurements using an ultrasonic anemometer at the Roman Rock Island. Integrated optical turbulence measurements were performed at two sites, over a path of 1.8 km and a long distance path of 8.6 km. The sites may be affected by local effects of the coastal environment. For comparison, the optical turbulence was modeled using micrometeorological parameterization. Additionally, the optical turbulence was determined by simulations using the weather research and forecast model WRF. Simulation results were compared to measurements considering seasonal and meteorological variations. The representativeness of the measurements locations for offshore measurements will be discussed.

The numerical LOTOS-EUROS model that provides information on the regional distribution of aerosols was implemented for a new domain, Southern Africa. The first set-up for the study areas is discussed and a comparison of model products (aerosol concentration and optical depth) to experimental data is presented. The model compares favorably to MODIS satellite products on a regional scale. Comparisons with in-situ instrumentation at specific locations reveal that the model generally capture temporal trends, but underestimates the absolute AOD-values. In the more pronounced case, this is attributed to the complex local orography of the measurement site that cannot be captured by the model.

A field trial was performed in the arid scrub area of White Sands, NM / USA in October 2017 investigating the atmospheric influence on imaging and sensor performance. In this paper we focus on the strength of optical turbulence. Optical turbulence is described by the structure function parameter of the refractive index 𝐶²_𝑛. It is responsible for beam wander, blurring. and scintillation. “Ground truth” measurements of optical turbulence were carried out using a Boundary Layer Scintillometer (BLS2000). The measurements were taken along an optical path of 3.64 km and a height of 1.5 m. Additionally, height dependency of 𝐶²_𝑛 is explored in the surface layer using 4 ultrasonic anemometers at discrete heights between 1 and 10 m. Power spectra of temperature were determined from time series of the ultrasonic anemometer data, which were inspected for the height dependency of spectral characteristics. The effect of the arid scrubs area on the applicability of Kolmogorov turbulence was investigated and discussed in this paper.

Wave propagation of electro-optical systems, lasers or imaging depends on the state of the atmosphere their beams are passing through. Fluctuations in the refractive index of air are responsible for signal attenuation and image degradation. This atmospheric effect is called optical turbulence and its strength is quantified by the structure function parameter of the refractive index 𝐶²_𝑛 . In the atmospheric surface layer it is highly variable. Usually 𝐶²_𝑛 decreases with height. In non-uniform terrain, big horizontal variations can arise. We developed a mobile airborne system for monitoring 𝐶²_𝑛 to investigate the three-dimensional character of optical turbulence. Therefore the dodecacopter system HORUS (Hovering Remote controlled Ultra-light Sensor-platform (AIRCLIP /Dresden/Germany)) was chosen as mobile platform. An ultrasonic anemometer was mounted on a boom for high-resolution measurements of temperature and wind speed. Analyzing the time series of temperature, 𝐶²_𝑛 values were derived from time averages of several minutes. The measurements took place in the surface layer over land in the vicinity of an 80 m high tower, equipped with ultrasonic anemometers at four discrete heights. Comparison measurements were performed. The minimum length of the boom outside the turbulent influence of the rotors was investigated. The comparison of the 𝐶²_𝑛 values shows a good agreement.

A second, smaller quadrocopter system in combination with a new very small and light-weight ultrasonic anemometer was also tested for turbulence measurements. The system is introduced and the applicability shown. Results from first field trials are presented and discussed.

This study compared the post-sunset and post-midnight equatorial spread-F (ESF) characteristics as well as their association with equatorial plasma bubbles (EPBs) and ionospheric scintillation. The occurrence of ESF was studied by looking at the percentage of monthly event intensity as well as seasonal variations during minimum solar activity (2008). This research used ionosonde, all-sky imager (ASI) and GPS receivers mounted on Kototabang (0.2°S, 100.3°E, -10.4° magnetic latitude) Indonesia. The occurrence of ESF were identified with two events, namely post-sunset (18:00-00:00 LT) and post-midnight (00:00-06:00 LT). From the observations, the percentage gained for ESF occurrence was 39.68%, with 18.01% for post-sunset and 21.67% for post-midnight, respectively. This suggests that the incidence of post-midnight ESF was greater than in post-sunset events during 2008. The occurrence of post-midnight ESF was more dominant in the summer solstice (May-July) with a value of 72.34%, while for post-sunset in equinoxes (Augustus- October) with a value of 62.79%. The correlation between the occurrence of ESF and EPBs show that post-sunset and post-midnight ESF averages are observed about ~30 minutes and ~60 minutes since the start of the EPBs. This reinforces the notion that one of the causes of the ESF is the instability that occurs below the elevation of the ionosphere F-layer indicating a movement of EPBs from the bottom-up processing. The occurrence of ESF has an impact on the incidence of scintillation, where at post-sunset ESF has a direct effect, whereas at post-midnight ESF it takes ~90 minutes to form scintillation, respectively.

We suggest a method for filtration of incoherent optical images of objects in the atmosphere, which allows one to observe cross shifts of turbulent air inhomogeneities at the observation path. It is shown that the characteristic size of anisoplanatic distortions in images observed through the atmosphere is mainly determined by the distance to the layer of turbulent inhomogeneities that cause these distortions. An algorithm is suggested for the filtration of turbulent distortions by their characteristic size in order to mark out the effect of turbulent medium layers specified. The capabilities of the algorithm for cross wind retrieval from the analysis of a video sequence of short-exposure images at surface horizontal paths are shown. The main advantage of the suggested method for cross wind retrieval from the analysis of two neighbor frames of video sequence is its high speed since there is no need to accumulate statistics of the analyzed parameters. The retrieved wind speed is compared with data of acoustic anemometers located along an observation path 500 m long. The good accuracy of retrieval of the cross wind at path segments close to an observer, as well as of the average wind speed over the entire observation path, is demonstrated.

We theoretically investigate the performance of adaptive-optics correction for Gaussian beams affected by oceanic turbulence. Action of adaptive optics is modeled as removal of a certain number of Zernike modes from the aberrated wavefront. We found that, similarly to atmospheric turbulence, adaptive optics is very effective to improve optical system performance of laser communication links in weak oceanic turbulence.

We introduce a method for creating temporally evolving wavefront distortions that uses Karhunen-Loève decomposition and the associated temporal power spectra. We demonstrate that the method is able to produce dynamic wavefronts that follow the behavior predicted by the theory while introducing key advantages in terms of calculation speed and storage in computer memory. Additionally we show how to: 1) create wavefronts that have propagated through multi-layer turbulence and 2) model the action of adaptive optics using the principles of frequency filtering.

First experimental demonstration of the device, providing measurement of Zernike polynomial in the incoming wavefront by the use of the Fourier-hologram, recorded with the use of diffuse scattered beam. Signal to noise ratio of such approach was investigated. It is shown that one can easily realize such a device, providing simultaneous and noiselacking measurement of several dozen Zernike modes.

Free-space optical communications (FSOC) are rapidly becoming a key technology for terrestrial, aerial, and space communication, mainly because of its very high throughput capacity. To achieve multi-gigabit laser downstream, an efficient single-mode fiber coupling is required. However, atmospheric turbulence remains one of FSOC’s main limitations. The turbulence affects the communications performance by inducing wavefront distortions that develop into coupled power fluctuations. In regimes of very strong turbulence, the use of traditional adaptive optics systems is limited due to strong scintillation and higher number of phase singularities. These limitations could be solved by relying on systems based on the stochastic iterative maximization of the coupled power. The drawback of such systems is that a high number of iterations are required for signal optimization. We address this problem and propose a different iterative method that compensates the distorted pupil phasefront by operating directly on the focal plane. The technique works by iteratively updating the phases of individual speckles to maximize the received power coupled into a single-mode fiber. We show numerically and experimentally that the method can improve the quality of the received signal with reduced bandwidth utilization.

A holographic wavefront sensor scheme using a phase-only spatial light modulator (SLM) with reduced cross-talk noise influence is proposed. A novel method for plane wave aberration measuring using a phase-only computer-generated hologram is devised. The proposed scheme and algorithm are validated with numerical simulations and experiments.

Possibilities of enhancing the operational efficiency of optical multiaperture systems in a turbulent atmosphere were studied through numerical simulation. Features of synthesizing an object image as a sum (superposition) of images from every individual aperture were analyzed in the presence of turbulent distortions. The quality of images synthesized by an array of N×N subapertures (N=5–15) was examined. It is shown that turbulent distortions in an image synthesized by many subapertures with allowance made for shifts of subimages at every subaperture are isoplanatic in a wide range of atmospheric conditions. This allows significant improvement of the image quality by means of computer correction. In this case, there is an optimal subaperture size mainly determined by the Fried parameter, which characterizes the degree of turbulent distortions.

Signal fading is a widely observed phenomenon in communication and sensing applications that results in spatially and temporally varying degradations in the received signal power. Specifically, for distributed acoustic sensing (DAS) applications based on phase sensitive Optical Time Domain Reflectometry (phase-OTDR), it is reported that optical signal fading is observed as random dramatic signal power fluctuations, which in turn cause substantial variations in threat detection sensitivity. In this paper, we study optical signal fading in the context of phase-OTDR based DAS from a signal processing perspective and analyze the undesired effects of fading on threat detection performance. Using a detailed phase-OTDR signal model, we analyze the effects of internal system parameters and external vibration source characteristics on optical fading. Based on these analyses, we define the conditions under which optical fading can manifest itself as a dramatic variation in threat detection performance.

A numerical model is developed to simulate the angle dependent light scattering. The model is based on Mie theory and uses the complex refractive indices of aerosol particles and rain droplets together with their corresponding experimental number size distributions as input parameters. The laser beam parameters of the high energy laser at the DLR laser transmission test range in Lampoldshausen and the geometry of the detection system are taken into consideration. It is demonstrated that the numerical model accurately predicts the absolute scattered powers obtained by a calibrated multiangle light scattering probe measuring under five different scattering angles. The model is applicable for dry and rainy weather conditions. In addition, Mie calculations are performed to determine the extinction coefficients at 1030 nm. The calculated extinction coefficients are correlated with meteorological parameters (i.e. rainfall intensity and visibility) obtained from different types of instruments. The calculated extinction coefficients are compared with the extinction coefficients derived from laser transmission experiments at 1030 nm. A good agreement between numerical results and measurements is observed under rainy weather conditions.

Measurements of parameters of the natural atmospheric environment, like aerosol and precipitation distributions as well as the visibility, are simultaneously performed together with the angle dependent scattering of high power laser radiation. These measurements were obtained on the free transmission test range operated by the German Aerospace Center (DLR) in Lampoldshausen. The applied high power disk laser system operates at a wavelength of 1030 nm and all presented measurements are performed at an output power of 3000 W in continuous wave. The laser beam is propagating along the 130 m test range and the focus is ten meters away from the detection setup for the scattered light. Each of the five detection systems consist of a fiber-coupled photoreceiver and all fiber-couplers are positioned on a stage at angles of 30°, 60°, 90°, 120° and 150°, respectively to the direction of the laser beam. The distance between the fiber-couplers and the detection volume is 500 mm and the aperture is about 22 mm. The laser beam is modulated at 10 Hz and the signals of the photoreceivers are transmitted to lock-in amplifiers. The transportable setup is protected by a weatherproofed box and is operated under various conditions and precipitations, like rain and snow. In order to obtain absolute values the detection systems are calibrated using an integrating sphere. The experimental setup of the calibration system is introduced and measurements of angle dependent absolute scattering powers in dependence on the power transmission loss, the geometric scattering coefficient and the visibility are shown.

Images acquired through underwater turbulent media make the image processing tasks in image restoration and object identification challenging. Turbulence in water is associated with random fluctuations of temperature and salinity. These fluctuations are responsible for changing the refractive index, for attenuating illumination, imposing geometric distortions and space-variant blur on images, thus making object identification more difficult. In this paper, we propose a patch-wise deconvolution procedure for removing the space-variant blur from images for restoration purpose prior to resolving the object identification issue. The deconvolution procedure is aided with an image alignment procedure for obtaining better results. Next, an image segmentation algorithm based on fuzzy clustering is considered for object identification. Computational experiments are conducted using a real-world dataset to demonstrate the efficiency of the proposed method.

The quadratic approximation of the high order Bessel Gaussian beams propagation through the non-Kolmogorov and the marine atmosphere is studied in this paper. Based on the extended Huygens–Fresnel principle, the intensity of the Bessel Gaussian beams propagation through the turbulence atmosphere is a quadruple integral, which could be simplified to a double integral when the spherical wave structure function is approximate to a quadratic function. And the intensity calculated by the Rytov method is a triple integral and studied as a comparison. In this paper, the accuracy of two methods is analyzed and the applicable condition is provided. The result of the Gaussian beam is also calculated to verify to presumption. And there will be a large bias between the extended Huygens–Fresnel principle with the quadratic approximation and the Rytov method when the inner scale of the turbulence is small and the Rytov method is better at this circumstance. This paper provides the theoretical basis for the application of the quadratic approximation.

Recently, we proposed an inexpensive deformable mirror made of Poly-Vinylidene Fluoride-(PVDF), called Vibrating Membrane Mirror (VMM), to compensate for optical atmospheric aberrations [1, 2]. The degree of similarity between the vibration mode shapes of a circular membrane and Zernike polynomials were investigated and VMM was introduced as a promising alternative to the traditional deformable mirrors. The present work deals with technical concepts, design, and surface analysis of the proposed deformable mirror. The mode identification, dynamic range, and time response of the proposed mirror is discussed and important factors that influence these parameters are investigated. To measure the mirror surface motion, a Laser Doppler vibrometer is used. Results show that the mechanical performance of the VMM satisfies the basic requirements of an optical deformable mirror. The mirror performance is optically examined in an interferometer setup and recommendations are provided to improve it.

The generation of optical beams with a possibility of quick variations in the orbital angular momentum (OAM) and the degree of spatial coherence is shown in laboratory experiments. The methods for OAM and coherence control are based on the phase control in the fiber array optical channels. The approach suggested allows one to change the OAM (the topological charge of a vortex beam) with a high speed determined by the phase shifter operation speed. The generation of a vortex beam is shown for six coherent Gauss-like beams arranged in a circle and having a constant phase shift between neighboring beams, providing the total phase shift equal to 2π around the circle. It is shown that the far field is characterized by an annular intensity distribution and a spiral-like distribution of the Poynting vector. In addition, the features of the OAM and the topological charge of a fiber-array-based vortex beam in a homogeneous medium are investigated in numerical experiments. The method for controlling the length of spatial coherence of the beam synthesized is based on introducing pseudo-random phase fluctuations in a fiber array. The value of the coherence length which exceeds the subbeam size is set by the correlation function of pseudo-random phase fluctuations in neighboring subbeams. The value of the coherence length smaller than beamlet size is set by the divergence of the subbeams with delta correlated phase fluctuations. The effect of the number of pseudo-random realizations of the fiber array phase on the average intensity distribution is studied in the laboratory experiments. The influence of the spatial coherence of the laser beam on the bit error rate of FSO communication systems in a turbulent atmosphere is studied theoretically.

Analytical formula for the average intensity of cylindrical vector vortex beams propagation in a non-Kolmogorov turbulent atmosphere is derived based on extended Huygens-Fresnel diffraction integral and be used to explore the evolution of the turbulence-induced spreading. For comparison, the corresponding results of the scalar vortex beams are compiled together. Scalar vortex beam can keep its original intensity pattern in the short propagation distance and evolve into the Gaussian-like beam with the increase of the propagation distance and turbulence structure parameter, and the decrease of power spectrum index, under the influence of atmospheric turbulence. An example illustrates the fact that, radially polarized vortex beams are more resistant to atmospheric turbulence than scalar vortex beams based on the view of disappearing characteristic of hollow structure. A radially polarized vortex beam has a better performance on the reduction of turbulence-induced beam spreading effects than its scalar counterpart. This indicates the potential advantages of using vector vortex to mitigate atmospheric effects and enable a more robust free space communication channel with longer link distance.

Turbulent fluctuations in the atmosphere distort a laser beam during its propagation. There exist two problems : (i) adequate description of the atmospheric turbulence and (ii) analysis of the propagation of the beam through turbulence, investigation of the beam spreading and distribution of its intensity. Unfortunately, only the scalar case of beam propagation has been considered often in the literature. Most part of authors studied only paraxial beams. Non-paraxial beams are considered in [1, 2]. Below we consider the propagation of a non-paraxial laser beam. The analysis has been made on the basis of the Maxwell equations. Two cases have been considered: (i) the permittivity and permeability are constant (the homogeneous atmosphere); (ii) the case when the permeability is equal to unity, the permittivity being dependent on coordinates. We assume that the permittivity is close to unity. Let us consider the first case. Some details of the solution were recently published in [3]. We have a linear system of ordinary differential equations with constant coefficients due to the Fourier transform. The unknown functions are determined from the condition at the plain x₃ = 0 ( x₃ being the coordinate along the axis of the beam). In the second case (the permittivity is the function of coordinates being close to unity) we have a system of linear ordinary differential equations after the Fourier transform, too. The right-hand terms depend on the previous solution which was obtained for the homogeneous atmosphere. The solution is the sum of that one for the homogeneous atmosphere and that one for the variable part of the permittivity. Thus we have the solution which describes the propagation of the non-paraxial beam through the inhomogeneous atmosphere on condition that the variation of the refractive index is small. Numerical calculations were fulfilled for the components of the electric field.

The dynamics of propagation of an optical vortex through an artificial enclosed atmospheric path was examined. The method of generating optical beams with a nonzero orbital angular momentum using a liquid-crystal HoloEye LC-2002 light modulator was demonstrated, and various methods for detecting optical vortices were tested. The distance at which the structure of the vortex beam decays for the technically possible aperture of the receiving interference system was determined under the conditions of the stand. The results of experimental studies of beam size at different distances were presented. Calculations of the beam and the singularity of the optical vortex divergence angle are performed as a function of the length of the atmospheric path. The influence of the turbulent medium on the ability of the receiving system to register an optical vortex was also considered.

Free Space Optical (FSO) systems offer tremendous channel capacity, which can significantly contribute to the bandwidthhungry next generation networks. FSO technology is certainly highly vulnerable to atmospheric Mie scattering, which leads to severe degradation of the established optical communication link. To address this key-issue, the current paper is focused on detailed investigation of the fog effect using artificially built fog environment. Low-visibility conditions are adjusted within a 50 m long corridor covered with PVC and including two artificial fog machines and a signal flare. The Particle Size Distributions (PSDs) of the simulated fog are measured with a sophisticated and so-called “Spraytec” device provided by Malvern Instruments Company. Once the main characteristics of the artificial fog are assessed, the measurements are compared with an empirical estimated fog model using modified gamma function. The comparison is accomplished in terms of theoretically defined PSDs where both radiation as well as advection fog modelling are taken into account. In order to calculate the relevant FSO channel attenuation only based on our measured fog PSDs, Mie theory is applied. For this purpose, Mie scattering efficiencies of a fog water sphere with arbitrary radius and refractive index are shown and examined. Respectively, apart from the presented figures with comparison of various PSDs, also the specific attenuation in dependence on fog particles size is introduced and discussed. Taking into account that particle density of the artificial fog can be manually setup in accordance with the applied theoretical models, our simulations offer attenuation up to 210 dB/km in the presence of continental moderate and dense fog effects. Consequently, we have the possibility to simulate significantly well various fog conditions in artificially simulated environment.

Optical geostationary orbit (GEO) satellites are one of the means to provide high speed internet and broadband services to even remote areas on the globe. However, the optical beam, as it propagates through the atmosphere, is affected by the atmospheric index of refraction turbulence and pointing errors due to beam wander and mechanical vibrations on the platform which result in fading, hence loss of signal. We present transmit diversity as a fading mitigation technique and use wavelength division to minimize cross interference between the transmitted signals. Optical single sideband (OSSB) scheme is used to increase spectral efficiency (SE) of the system. We demonstrate a scheme where an OSSB signal is produced using commercially available optical filter with tunable bandwidth and center frequency. For a 32Gbps data signal modulated using amplitude shift keying (ASK), we measure the required minimum 6dB and 20dB bandwidths of the optical filter to be 12GHz and 24GHz, respectively. Also, the offset of the filter from the carrier is found to be -11GHz and +10GHz to produce an error free lower and upper OSSB signal, respectively. The SE of the OSSB signal is found to be 1.34 bit/s/Hz. Moreover the stability of the optical filters and carrier ensure reliable signal generation making the OSSB a potential candidate to be used in future free space optical links.

In the charge-coupled device(CCD)-based optoelectronic system(OS)，the external disturbance has a bad influence on the line-of-sight(LOS) stabilization, especially in a moving platform. Generally, with a high-performance fiber-optic gyroscope(FOG), we build a velocity inner loop to enhance the disturbance suppression ability(DSA). However, FOG has a big size, high cost and power consumption which limit its application in space-constrained occasion. With the development of the micro-electro-mechanical system(MEMS) industry, the MEMS accelerometer and gyro are more used in the optoelectronic field for their small volume and low price. Since the MEMS accelerometer has a much higher bandwidth than the MEMS gyro, it’s more suitable to build a high-bandwidth and high-sampling inner loop to enhance the DSA. Unfortunately, since the signal of the MEMS accelerometer in low frequency is weak and commonly with drift and much noise, the low-frequency DSA of the inner loop is insufficient. Considering the CCD has a good low-frequency signal and the MEMS accelerometer has an advantage in high frequency, based on the acceleration and position double-loop control(APDC), we proposed to add an additional velocity loop by fusing the CCD’s low-frequency signal and the accelerometer’s high-frequency signal with an open-loop bandwidth fusion method(OBF) to further enhance the DSA. The fusion velocity even has a higher bandwidth than the MEMS gyro. A series of comparative experimental results demonstrate the proposed method could get a lightweight OS with a strong DSA, which is close to the triple loop control based on the MEMS accelerometer and real gyro, and even has a better DSA in medium frequency.

The present study aims to achieve high volume manufacturing of nanofabrication techniques for optical MEMS devices and expand the resolution limits of ecofriendly developable processes in advanced lithography using the new family of positive-tone nano-patterning materials derived from biomass. The volume manufacturing of nanofabrication techniques and resolution limits of the ecofriendly developable processes using the 50 nm positive-tone nano-patterning materials was dramatically improved by changing and approached the existing resolution limits of non-ecofriendly development processes involving highly toxic organic solvents and tetramethylammonium hydroxide. The newly biomass material and the ecofriendly processes are expected as one of the nanofabrication techniques in next generation optical MEMS devices.

MEMS technology is incorporated into various devices (automobiles, digital cameras, optical devices) indispensable for our daily lives. Semiconductor manufacturing process technology such as photolithography method and ion beam method is mainly used for micropatterning necessary for MEMS and microfabrication of diffraction grating. In photolithography, many transfer defects caused by gas are generated. Therefore, a metal plate having gas permeability was prepared with a 3D printer, and the surface and internal structure of the metal plate was evaluated. Further, the porosity of the metal plate was calculated by measuring the size and weight of the produced metal plate. As a result, it was confirmed that there were numerous holes in the inside of the metallic material, and it was confirmed that the hole having the role of permeating the gas and the hole having the role of temporarily preserving the gas. Furthermore, it was also confirmed that the porosity of the metal plate is about 10%. Metallic materials with gas permeability can be expected to be materials required for MEMS device processing.

The electronic substrate used for the MEMS device is finely processed, and imprint lithography is often used as a processing method. However, in the printing process, gas is caught in the molding material, and transfer failure frequently occurs. Therefore, in this study, a gas permeable metal plate with a gas permeable structure inside was fabricated and imprinted on a material to be transferred containing 50% of volatile material. As a result, no gas pool was observed and imprinting was possible without defective transfer. This not only prevents entrainment of gas at the time of imprinting, but also a transfer material containing a volatile solvent can be used as a material to be transferred. It is greatly expected that the developed gas permeable metal plate becomes a material necessary for MEMS device processing.