Polished Face Research Articles

Effective alignment method using a diamond notch knife for correlative array tomography.

Correlative array tomography, combining light and electron microscopy via serial sections, plays a crucial role in the three-dimensional ultrastructural visualization and molecular distribution analysis in biological structures. To address the challenges of aligning fluorescence and electron microscopy images and aligning serial sections of irregularly shaped biological specimens, we developed a diamond notch knife, a new tool for puncturing holes using a diamond needle. The diamond needle featured a triangular and right-angled tip, enabling the drilling of deep holes upon insertion into the polished block face. This study describes the application of the diamond notch knife in correlative array tomography.

Effect of dislocations on carrier recombination and photoelectrochemical activity in polished and unpolished TiO2 and SrTiO3 crystals

TiO2 and SrTiO3 are stable and efficient materials for photoelectrochemical (PEC) water splitting. PEC activity is influenced by carrier recombination in crystals of these materials. In this study, we analyzed the effect of dislocations on carrier recombination in TiO2 and SrTiO3 using microwave photoconductive decay measurements on polished and unpolished faces. The apparent slow decay in the unpolished face implies that dislocations trap minority carriers. Based on the different dependences of the injected photon density and temperature, the recombination processes in the polished and unpolished faces differ. A high concentration of oxygen vacancies or hydroxyl in the unpolished face of SrTiO3 was observed by x-ray photoelectron spectroscopy, and dislocations in the unpolished faces of both materials were observed using transmission electron microscopy. Additionally, we found that the photocurrent duration in the unpolished faces was shorter than that in the polished faces for both TiO2 and SrTiO3, confirming that dislocations inhibited photoelectrochemical activity.

Evanescent wave quartz-enhanced photoacoustic spectroscopy employing a side-polished fiber for methane sensing

We present an all-fiber-based laser gas analyzer (LGA) employing quartz-enhanced photoacoustic spectroscopy (QEPAS) and a side-polished fiber (SPF). The LGA comprises a custom quartz tuning fork (QTF) with 0.8 mm prong spacing, two acoustic micro-resonators (mR) located on either side of the prong spacing, and a single-mode fiber containing a 17 mm polished section passing through both mRs and QTF. The SPF polished face is positioned to enable the evanescent wave (EW) to create a photoacoustic wave and excite the fundamental flexural mode of the QTF. Sensor performance was demonstrated using methane in nitrogen gas mixtures, with CH4 mixing ratios ranging from 75 ppmv to 1% (by volume), measured with an accumulation time of 300 ms, and a minimum detection limit of 34 ppmv subsequently determined. The EW-QEPAS sensor is ideal for miniaturization, as it does not contain any free-space optics and is suitable for gas sensing in harsh environments and where mobility is required.

Before and after: A visual glimpse into the coking behaviour of coal macerals

Coal petrography as a tool for predicting coke quality has been employed for many decades. This paper first provides a brief review of some of the founding research in this area and secondly proposes and demonstrates a technique for direct optical comparison of a semicoke to its exact piece of precursory coal to observe the pyrolysis behaviour of individual macerals. The technique involves imaging a polished block sample of coal (with the polished face of interest having orientation perpendicular to the bedding layers), pyrolysing the sample in a furnace up to 525°C under conditions attempting to mimic those in a coke oven, embedding the resulting semicoke in resin and lightly re-polishing and re-imaging the surface of interest. Comparison of the optical images of the sample pre- and post-pyrolysis enables a 2-dimensional visual assessment of the coking behaviour of the inherent macerals. This method was applied to two Permian coals: a Mozambican coal with random reflectance of 1.21% and an Australian coal with random reflectance of 1.28%. The main observations were (i) anisotropic swelling, with swelling much greater in the direction perpendicular to the bedding layers compared to that parallel, (ii) noticeably different pore structure arising from the vitrinite macerals collotelinite and collodetrinite, and (iii) visual evidence of semifusinite reactivity. It is intended that application of this technique will enhance the fundamental understanding of maceral specific coking behaviour and thus assist coke-makers with their blend formulations.

FRACTURE OF 30CRMNSIA STEEL UNDER MIXED LOADING MODES

Tests were conducted on notched specimens made of 30CrMnSiA steel in loading mode I with the fracture surface perpendicular to the loading direction (90°) and in mode II with shear angles of 45° and 15°. Shear loading was performed using Richard’s grips that allow for a transition from pure mode I to pure mode II by varying the angle of the notch in relation to the direction of the tensile load. Using digital image correlation, the acoustic emission (AE) signals and the strain field were measured during testing, and the damage and microhardness of the polished side face of the specimens were evaluated after failure. The macro- and microscopic research of fracture surfaces revealed that an increase in the shear component during tension leads to changes in the mechanical and acoustic properties and the ductile-to-brittle-transition temperature. This is evidenced by a change of the fracture surface morphology from ductile to brittle at 45° loading direction, accompanied by a change in all estimated acoustic parameters (the total number of events, the angular coefficient of the cumulative distribution of acoustic signals by amplitude-b-value, and the activity of AE signals). An increase in the shear component also leads to a nonlinear dependence of the damage parameters on the load application angle, such as the relative microcrack area S*, average microcrack length lav, and microcrack inclination angle with respect to the loading axis, which correlate with the change in the principal strains estimated by digital image correlation.

Work-related problems faced by coordinators of organ, cell, and tissue transplantations in Poland and possible ways of ameliorating them

In recent years in Poland, the numbers of reported potential cadaveric donors of organs, tissues, and cells, and the numbers of transplantations being carried out seem to be low in the context of the size of the country population and the presumed consent legal principle which rules transplantations. This research project was carried out on 109 Polish transplant coordinators by means of a questionnaire created specifically for this study. The goal of the project was to detect problems specific to transplant coordinators working in Poland which, when properly addressed, might improve the efficacy of transplantation network within the Polish health care system. The results suggest that Polish transplant coordinators face a variety of issues in their work. It appears that the most important interventions which could improve working conditions for in this population and—as a result—also improve the efficacy of transplantation network in Poland could include: (1) a variety of training programs for transplant coordinators; (2) a social campaign promoting transplantations and spreading awareness of the transplantation-related legislation; and (3) introduction of changes in the regulations pertaining to medical professions in Poland.

Mineralogical and Geochemical Features of Native Gold From Placers of the Evota Gold-Bearing Region (Russia, Aldan Shield)

Evota gold-bearing region is located in south of Republic Sakha (Yakutia) within the Nimnyr terrane of Aldan shield. A large numbers of gold-bearing placers are known on studied territory, but the primary sources for them have not been established. In this work, based on the study of the mineralogical and geochemical features of gold from alluvial deposits of the Evota gold-bearing region, possible genetic types of primary sources are considered. Obtained data showed that native gold in the studied objects has a very high, high and medium fineness. The roundness of gold is different. Almost ore crystals with sharp edges and well-rounded individuals with polished faces were found. The fineness of the studied gold grains was determined by microprobe analyzer Cameca Camebax-micro and varies in the range from 812 to 1000 %⁰. A thin (up to 20 μm) high-grade rim was found in two grains (cr. Zolotoy). The central part of one of them has a fineness of 865 %o, and in the edge part it reaches 1000 %⁰, which indicates that this gold was in the hypergenesis zone. Admixture elements determined as traces and are presented Cu, Pd, Fe, Ni. Minerals-microinclusions - quartz, potassium feldspar, pyroxene, staurolite, maldonite, bismuthite revealed in gold grains. In some watercourses, for example, in the creek Sukhoi, only very high fineness gold (993-1000 %⁰) was found. The presence of high-grade gold (cr. Sukhoi), intergrowths of gold with bismuthite (cr. Zolotoy), as well as inclusions of maldonite (cr. Yagodny) gives opportunity for assuming that primary sources could be basic ores such presented in the P. Pinigin deposit. At the sites (cr. Elovyi, r. Evota), both medium-grade and very high-grade gold were found, the fineness range varied from 827 to 998 %⁰. The presence of gold with medium fineness and good roundness in studied watercourses probably indicates an additional supply of gold from primary sources formed as a result of the alkaline magmatism development of the Mesozoic age. Thus, for gold with high and very high fineness by admixture-elements, chemical composition and microinclusions, a genetic relationship with primary sources similar to the P. Pinigin deposit was found; for gold grains with medium fineness, formation in gold-ore mineralization characterized for the Mesozoic stage ore development such in deposits of Central-Aldan ore region is assumed.

Surface microstructures developed on polished quartz crystals embedded in wet quartz sand compacted under hydrothermal conditions

Intergranular pressure solution plays a key role as a deformation mechanism during diagenesis and in fault sealing and healing. Here, we present microstructural observations following experiments conducted on quartz aggregates under conditions known to favor pressure solution. We conducted two long term experiments in which a quartz crystal with polished faces of known crystallographic orientation was embedded in a matrix of randomly oriented quartz sand grains. For about two months an effective axial stress of 15 MPa was applied in one experiment, and an effective confining pressure of 28 MPa in the second. Loading occurred at 350 °C in the presence of a silica-saturated aqueous solution. In the first experiment, quartz sand grains in contact with polished quartz prism (overline10{1 }0) faces became ubiquitously truncated against these faces, without indenting or pitting them. By contrast, numerous sand-grain-shaped pits formed in polished pyramidal (17overline{6 }3) and (overline{4 }134) crystal faces in the second experiment. In addition, four-leaved and (in some cases) three-leafed clover-shaped zones of precipitation formed on these prism faces, in a consistent orientation and pattern around individual pits. The microstructures observed in both experiments were interpreted as evidence for the operation of intergranular pressure solution. The dependence of the observed indentation/truncation microstructures on crystal face orientation can be explained by crystallographic control of stress-induced quartz dissolution kinetics, in line with previously published experimental and petrographic data, or possibly by an effect of contact orientation on the stress-induced driving force for pressure solution. This should be investigated in future experiments, providing data and microstructures which enable further mechanism-based analysis of deformation by pressure solution and the effect of crystallographic control on its kinetics in quartz-rich sands and sandstones.

Effects of thermal annealing on the characterization of p-NiO/n-GaAs heterojunctions produced by thermal evaporation

In this study, p-NiO/n-GaAs heterojunctions were fabricated using the thermal evaporation method that least affects the physical properties of the target sample. For the n-GaAs [100] crystal, all the cleaning process was carried out according to the conventional procedures. After making an ohmic contact with Au (99.9%) metal on the back mat face of the n-GaA single crystals, NiO was thermal evaporated on the front polished face of the crystal. Optical transmittance values of the NiO thin films were determined by a UV–Visible (UV–Vis) spectrophotometer. The optical band gaps of non-annealed and annealed NiO thin films were determined as 3.54 and 3.48 eV, respectively. XRD, SEM, EDX and AFM measurements were also performed to examine the effect of annealing in NiO thin films. Current–voltage (I-V) measurements of NiO/GaAs heterojunctions were made to determine photoelectric and electrical properties under illumination and in the dark. The energy dependence of interface states (Nss) were extracted from the I-V measurements by assuming the voltage dependence of the barrier height Фb and the ideality factor n. The NiO/GaAs contacts were found to have a good rectifier and photodiode properties from the I-V graphics.

Lithium niobate planar and ridge waveguides fabricated by 3 MeV oxygen ion implantation and precise diamond dicing

We report on the fabrication and optimization of lithium niobate planar and ridge waveguides at the wavelength of 633 nm. To obtain a planar waveguide, oxygen ions with an energy of 3.0 MeV and a fluence of 1.5×1015 ions/cm2 are implanted in the polished face of LiNbO3 crystals. For planar waveguides, a loss of 0.5 dB/cm is obtained after annealing at 300°C for 30 min. The ridge waveguide is fabricated by the diamond blade dicing method on optimized planar waveguides. The guiding properties are investigated by prism coupling and end-face coupling methods.

A Whispering Gallery Mode Microsphere Resonator Integrated With Angle Polished Multimode Fiber

We demonstrate a robust whispering-gallery-mode (WGM) microsphere resonator, fabricated by splicing two sections of multimode fiber (MMF) with end face polished to an angle of 45 degree. The polished end faces are etched by hydrofluoric (HF) acid to form an elliptical-shaped cavity to embed a microsphere before being firmly connected by UV adhesive. Part of the incident light traveling along the fiber core is coupled into the microsphere in the tangential direction to the surface of the microsphere and excites WGM. Such a microsphere resonator is highly robust and compact in size, and has a Q-factor of 5.15 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . When used as a temperature sensor, the sensitivity obtained is 6.4 pm/°C.

Susceptibilidade à corrosão intergranular e por pites do aço inoxidável austenítico AISI 347 soldado e solubilizado

A susceptibilidade ao ataque intergranular e por pites nos aços inoxidáveis austeníticos é resultado do fenômeno de sensitização, que ocorre quando esses aços são utilizados em temperaturas entre 480-815 °C. Neste trabalho foi avaliada a susceptibilidade à corrosão intergranular e por pites de amostras de aço inoxidável austenítico AISI 347 nas condições: soldado sem tratamento térmico, soldado e solubilizado a 1060 °C por 27 min e a 950°C por 5h. Para avaliar a resistência à corrosão, foram realizados: ensaio de susceptibilidade a corrosão intergranular (de acordo com a norma ASTM 262 – 02A) e teste de resistência a corrosão por pites (de acordo com a norma ASTM G48). A caracterização microestrutural consistiu de análises por microscopia ótica confocal (MO) e, a partir das micrografias obtidas, foi quantificada a fração volumétrica dos constituíntes presentes de acordo com a norma ASTM E 562-02. Os ensaios mostraram que as amostras solubilizadas após a soldagem apresentaram uma redução de 34% p. na fração de ferrita delta presente na ZF. Na análise da susceptibilidade a corrosão intergranular, observou-se que o material soldado solubilizado a 1060°C foi o mais susceptível. Na análise da susceptibilidade à corrosão por pites, a amostra soldada solubilizada a 1060°C apresentou maior quantidade de pites profundos na face polida (concentrados principalmente na ZTA e no MB). Também foi observada a relação entre o acabamento superficial das amostras e a perda de massa: a amostra soldada solubilizada a 950°C apresentou a maior perda de massa pois possuía as piores condições de acabamento superficial.

Study of Fe ions in aquamarine and the effect of dichroism as seen using UV–Vis, NIR and x-ray

The oxidation states and coordination environment of Fe in 4 aquamarine samples with different color shades were studied. The C axis along with plane A and plane C of the samples were identified and the measurements were made with plane A oriented facing incoming beam and plane C oriented facing incoming beam. NIR and Raman spectroscopy were employed to confirm the structure of the samples. XRD was used to confirm the polished faces. UV–Vis and X-ray absorption near edge structure (XANES) were used to identify the presence of both Fe2+ and Fe3+ in the samples. The results indicated that Fe resided predominantly in 6-fold coordinated sites and the deep blue shade depended on the amount of Fe2+ in 6-fold coordinated sites. The effect of dichroism was noticeable in NIR, Raman spectroscopy, UV–Vis and XANES. Clearer Raman bands were observed when samples were oriented with plane A facing laser source. NIR and UV–Vis analysis could benefit from the complementarity of spectra measured from both orientations. Discrepancies between XANES spectra measured from the two orientations could lead to uncertainties in obtained values of oxidation states.

The Clash of Economic and Religious Fundamentalism in Aslam's The Blind Man's Garden

This study aims to understand the clashes between American economic fundamentalists and Islamic religious fundamentalists in South Asia regarding Nadeem Aslam's The Blind Man's Garden (2013). The study explores that the economic entrepreneurs of the neo-imperialists give birth to counterproductive acts of religiosity. It shows how the ugliness of economic hunger is adroitly hidden behind the polished face of globalization, just as the priggish and snobbish religiosity of Muslim fundamentalists encloses their avarice for power and wealth. Using Tariq Ali's theory of Clashes of Fundamentalisms, the study proves that the root cause of civilizational clashes is the outcome of conflicts of interests between Western economic fundamentalists and Muslim religious fundamentalists. The study concludes the economic, political, cultural and strategic motives working behind the goals of establishing neo-imperialism through the elimination of borders for neo-liberalist gains in the wake of the war on terror.

The Effect of Shot Peening on Steam Oxidation of 304H Stainless Steel

Shot peening is currently utilized in coal-fired power plant components to mitigate scale exfoliation issues from steamside oxidation of austenitic stainless steel superheater and reheater tubing. To focus on commercially available material, this study exposed quarter-ring specimens cut from two different commercially shot peened type 304H tubes and exposed to 1 bar steam for up to 15,000 h at 550°, 600°, 625°, and 650 °C. Specimens were removed at increments to characterize the oxide thickness and microstructure. The shot peened inner surface generally retained a thin, protective Cr-rich scale with occasional Fe-rich oxide nodules at 550–625 °C. The increased oxidation resistance from shot peening began to degrade at 650 °C after as little as 5,000 h. Cut and polished faces of these specimens formed thick, Fe-rich oxides similar to polished 304H coupons. Surprisingly, the mechanically machined outer surface of the tube specimens performed similarly to the shot peened inner diameter, suggesting it had sufficient cold work to achieve a similar benefit. Electron backscatter diffraction and Vickers-hardness measurements were used to characterize post-exposure changes in underlying microstructure and mechanical properties, respectively, imparted by shot peening.

LES ÉTUDIANTS POLONOPHONES FACE AUX VOYELLES NASALES FRANÇAISES

In the process of the acquisition of the sound system of French as a foreign language, Polish students face numerous difficulties at the level of recognition, differentiation and correct production of French vowels. This is true for oral and nasal vowels. This article concentrates on nasal vowels, and its aim is to present a comparative description of nasal vowels in Polish and French, including recent changes in their production. Moreover, the paper presents the study reporting difficulty with correct perception and articulation of French nasal vowels faced by advanced Polish learners of French. While the paper does not describe corrective proce-dures, it indicates the necessity of undertaking further studies aiming at optimizing the process of the acquisition of the sound system in a foreign language.

An integrated application of chemo-ultrasonic approach for improving surface finish of Si (100) using double disk magnetic abrasive finishing

The present research article evaluates the performance of ultrasonic and chemically assisted double disk magnetic abrasive finishing (DDMAF) on polishing Si (100). The process parameters namely polishing speed, working gap, and pulse on time with five levels of each have been utilized to explore the surface roughness of polished Si (100). The statistical analysis revealed that polishing speed with a share of 71.1% was the most significant process parameter swaying the process performance on surface roughness. Furthermore, the share of working gap and pulse on time was found to be 3.04% and 1.65% respectively. The polishing speed interaction with pulse on time was found more influencing having share of 10.69% on surface roughness followed by working gap and pulse on time interaction with a share of 3.58%. The pooled regression equation with significant process parameters was used to obtain minimum surface roughness using genetic algorithm (GA) function available with MatLab 13 software package. The best polished face of Si (100) having surface roughness of 11.6 nm under optimum polishing condition has been achieved (1.5 nm on atomic force microscopy (AFM) scale). The scanning electron microscopy (SEM) and AFM inspections under optimum polishing condition of polished Si (100) were carried out. From the topographical inspection, it was observed that no scratch marks existed in the polishing direction. An evenly polished surface was obtained after polishing Si (100) under the influence of ultrasonic and chemically assisted DDMAF.

Automated precision alignment of optical components for hydroxide catalysis bonding.

We describe an interferometric system that can measure the alignment and separation of a polished face of a optical component and an adjacent polished surface. Accuracies achieved are ∼ 1μrad for the relative angles in two orthogonal directions and ∼ 30μm in separation. We describe the use of this readout system to automate the process of hydroxide catalysis bonding of a fused-silica component to a fused-silica baseplate. The complete alignment and bonding sequence was typically achieved in a timescale of a few minutes, followed by an initial cure of 10 minutes. A series of bonds were performed using two fluids - a simple sodium hydroxide solution and a sodium hydroxide solution with some sodium silicate solution added. In each case we achieved final bonded component angular alignment within 10 μrad and position in the critical direction within 4 μm of the planned targets. The small movements of the component during the initial bonding and curing phases were monitored. The bonds made using the sodium silicate mixture achieved their final bonded alignment over a period of ∼ 15 hours. Bonds using the simple sodium hydroxide solution achieved their final alignment in a much shorter time of a few minutes. The automated system promises to speed the manufacture of precision-aligned assemblies using hydroxide catalysis bonding by more than an order of magnitude over the more manual approach used to build the optical interferometer at the heart of the recent ESA LISA Pathfinder technology demonstrator mission. This novel approach will be key to the time-efficient and low-risk manufacture of the complex optical systems needed for the forthcoming ESA spaceborne gravitational waves observatory mission, provisionally named LISA.

Single-angle reflectance spectroscopy to determine the optical constants n and k: considerations in the far-infrared domain.

Single-angle infrared (IR) reflectance spectroscopy is a proven and effective method for determining the complex optical constants n and k of condensed matter. The modern method uses a Fourier transform IR spectrometer to record the quantitative reflectance R(ν) spectra followed by application of the Kramers-Kronig transform (KKT) to obtain the complex optical constants. In order to carry out the KKT, it is essential to measure the reflectance spectra to as high and low a frequency (wavenumber) as possible. Traditionally, the reflectance spectra of solid specimens consist of large (typically>10 mm diameter) polished single-crystal faces free of defects or voids. The requirement of a large polished face, however, is not a realistic expectation for many synthetic, geologic, or rare specimens where the size is usually small and the morphology can vary. In this paper we discuss several improvements and considerations to both the hardware and far-IR measurement protocols that lead to more accurate R(ν) values and thus to more accurate n/k values, especially for small (millimeter-sized) specimens where the R(ν) spectrum is concatenated from multiple independent R(ν) spectra from overlapping hardware/spectral domains. Specifically, the improved hardware and analyses introduced here include the following: (1) providing a set of far-IR calibration standards; (2) custom-designing and manufacturing low reflectivity, stray-light reducing sample masks for small specimens; (3) minimizing stray light interaction between the sample mask, the interferometer Jacquinot stop, and the detector; (4) optimizing the methods to "splice" together the spectra from independent domains; (5) discussing what methods one can use to obtain or calculate the important R(0 cm-1) value; (6) using a quartic relationship to extrapolate from the measured R data to R(0); and (7) accounting for the limiting effects of diffraction for the spot size at the sample mask and detector for millimeter-sized specimens, especially at the very long wavelengths. These seven considerations are all highly interconnected and are discussed in turn, as well as their strong interdependencies. This paper presents a holistic approach for determining reliable n/k values of millimeter-sized samples using single-angle reflectance in the mid- and far-IR.

An edge-readout, multilayer detector for positron emission tomography.

PurposeWe present a novel gamma‐ray‐detector design based on total internal reflection (TIR) of scintillation photons within a crystal that addresses many limitations of traditional PET detectors. Our approach has appealing features, including submillimeter lateral resolution, DOI positioning from layer thickness, and excellent energy resolution. The design places light sensors on the edges of a stack of scintillator slabs separated by small air gaps and exploits the phenomenon that more than 80% of scintillation light emitted during a gamma‐ray event reaches the edges of a thin crystal with polished faces due to TIR. Gamma‐ray stopping power is achieved by stacking multiple layers, and DOI is determined by which layer the gamma ray interacts in.MethodThe concept of edge readouts of a thin slab was verified by Monte Carlo simulation of scintillation light transport. An LYSO crystal of dimensions 50.8 mm × 50.8 mm × 3.0 mm was modeled with five rectangular SiPMs placed along each edge face. The mean‐detector‐response functions (MDRFs) were calculated by simulating signals from 511 keV gamma‐ray interactions in a grid of locations. Simulations were carried out to study the influence of choice of scintillator material and dimensions, gamma‐ray photon energies, introduction of laser or mechanically induced optical barriers (LIOBs, MIOBs), and refractive indices of optical‐coupling media and SiPM windows. We also analyzed timing performance including influence of gamma‐ray interaction position and presence of optical barriers. We also modeled and built a prototype detector, a 27.4 mm × 27.4 mm × 3.0 mm CsI(Tl) crystal with 4 SiPMs per edge to experimentally validate the results predicted by the simulations. The prototype detector used CsI(Tl) crystals from Proteus outfitted with 16 Hamamatsu model S13360‐6050PE MPPCs read out by an AiT‐16‐channel readout. The MDRFs were measured by scanning the detector with a collimated beam of 662‐keV photons from a 137Cs source. The spatial resolution was experimentally determined by imaging a tungsten slit that created a beam of 0.44 mm (FWHM) width normal to the detector surface. The energy resolution was evaluated by analyzing list‐mode data from flood illumination by the 137Cs source.ResultWe find that in a block‐detector‐sized LYSO layer read out by five SiPMs per edge, illuminated by 511‐keV photons, the average resolution is 1.49 mm (FWHM). With the introduction of optical barriers, average spatial resolution improves to 0.56 mm (FWHM). The DOI resolution is the layer thickness of 3.0 mm. We also find that optical‐coupling media and SiPM‐window materials have an impact on spatial resolution. The timing simulation with LYSO crystal yields a coincidence resolving time (CRT) of 200–400 ps, which is slightly position dependent. And the introduction of optical barriers has minimum influence. The prototype CsI(Tl) detector, with a smaller area and fewer SiPMs, was measured to have central‐area spatial resolutions of 0.70 and 0.39 mm without and with optical barriers, respectively. These results match well with our simulations. An energy resolution of 6.4% was achieved at 662 keV.ConclusionA detector design based on a stack of monolithic scintillator layers that uses edge readouts offers several advantages over current block detectors for PET. For example, there is no tradeoff between spatial resolution and detection sensitivity since no reflector material displaces scintillator crystal, and submillimeter resolution can be achieved. DOI information is readily available, and excellent timing and energy resolutions are possible.