大量程位移传感器用于三等量块检定时的不确定度分析

近年来,随着光电技术的发展,国内外出现了一系列基于光栅技术的高准确度大行程的位移传感器。光栅类传感器与其他传感器如电感、电容、容栅等比较,具有测量重复性好、准确度高、测量范围大的特点,特别是在较大行程时仍能保持非常好的线性。此外,由于电子细分技术和计算机技术的发展,大大提高了光栅类传感器的准确度,较高准确度的光栅类传感器在25mm测量范围内的最大示值误差可达到MPE=±(0.03 0.5l)μm(式中:l为测量长度,单位:m)。国外生产这类光栅传感器的厂家主要是德国HEIDENHAIN公司,国内也有厂家成功研制了这类传感器。这类光栅…     

大量程位移传感器用于指示类量具检定仪的示值检定时的不确定度分析

近几年来,国内外出现了一些基于光栅技术的高准确度大量程的位移传感器,其具有测量重复性好、准确度高、测量范围大、容易携带的特点,可对较大型的光栅式指示表检定仪进行现场检定。文章从技术角度对其检定的不确定度进行了分析,并验证了对光栅式指示表检定仪开展检定的可行性。     

三等量块比较测量不确定度的估算

测量结果的可靠性或测量结果的质量均是由其测量不确定度来表征的。本文拟以三等量块比较测量为例，依据《ＪＪＧ１４６￣９４量块检定规程》，参照国际标准化组织（ＩＳＯ）、国际法制计量组织（ＯＩＭＬ）等共同颁布的《测量不确定度表征方法指南》进行测量不确定度分析估算。     

三等量块测量不确定度评定

不确定度是测量工作的质量和测量结果可信赖程度和评价。按JJF1059.1-2012标准规定,对三等量块不确定度评定。     

三等量块比较测量不确定度的估算

测量结果的可靠性或测量结果的质量均是由其测量不确定度来表征的。本文拟以三等量块比较测量为例，依据《JJG146—94量块检定规程》，参照国际标准化组织（Ito）、国际法制计量组织（OIML）等共同颁布的《测量不确定度表征方法指南》进行测量不确定度分析估算。     

量块比较检定中测量不确定度评定

本文在阐述测量不确定度及其相关概念理解与表示的同时 ,以量块检定中测量不确定度评定为例 ,说明在实际问题中如何给出测量结果。     

三等量块标准装置不确定度评定

不确定度是测量工作的质量和测量结果可信赖程度和评价。利用三等量块、接触式干涉仪、平面平晶、温度湿度计、干涉显微镜等组成建立三等量块标准装置,通过对三等量块标准装置测量不确定度来源的分析,评定了三等量块标准装置测量不确定度大小,分析得到的结果满足采用比较测量法检定四等及四等以下量块。     

三等125～1000mm量块检定温控量化分析

通过对量块检定的不确定度分析中环境温度的影响进行量化计算 ,给出量块检定中温度控制的范围。     

非常规尺寸量块检定时标准量块的选择及测量不确定度的评定

本文着重于非常规尺寸(就是没有合适尺寸的标准,通过几块标准量块研合而成的尺寸)量块的不确定度的评定,以及检定时标准量块的选择。     

测量不确定度在烟尘测试仪检定中的应用

测量结果不确定度的应用范围很广,从原则上说,在给出任何测量结果的同时均应该给出测量结果的不确定度。不确定度按其获得的方法分为A、B两类评定分量,若要得到某测量结果的不确定度,必须根据其仪器、设备、实验方法、人员素质、环境条件等因素提出完整的数学模型。本文依照具体情况给出本实验测量结果的不确定度。     

Nature of heterophase inclusions in high-purity optical fiber materials as studied with 3D laser ultramicroscopy

3D laser ultramicroscopy (3D LUM) is intended specially for determining the concentration and size distribution of submicron inclusions in the bulk samples of high-purity materials for visible and IR fiber optics. In this work the 3D LUM technique is shown to be able to identify the nature of individual inclusions detected. The measurement of the light scattered by an inclusion at a varied probe beam wavelength and polarization and at a varied scattered light collection angle makes it possible to determine the inclusion refractive index. The 3D LUM possibilities are illustrated by the example of studying the inclusion nature in the As₂S₃ glass samples prepared by the direct synthesis from elements in a quartz container at elevated temperatures.     

Mid-infrared (2.5 ≤ λ ≤ 12.5 μm) optical absorption enhancement of textured silicon surfaces coated with an antireflective thin film

High-performance solar cells and optical detection devices frequently incorporate microscopic surface texturing and antireflective (AR) thin films to reduce the reflection of incident radiation and, thus, enhance optical absorption. Using conventional electrochemical and single-crystal silicon micromachining techniques, porous silicon (PS) and textured surfaces composed of randomly spaced and sized pyramids (RSSPs) were fabricated and optically characterized over the mid-infrared (2.5 ≤ λ ≤ 12.5 μm) portion of the optical spectrum. The utility of a 1.53 ± 0.03 μm thick yttrium oxide (Y₂O₃) AR thin film was also investigated in an attempt to enhance optical absorption. The optical measurements were accomplished using a 21 ° incident illumination angle (measured with respect to the sample's normal) and a Bomem® total integrating sphere to quantify the total (specular and diffuse) reflectance (R). A highly-polished, uncoated, single-crystal silicon wafer was used as a reference surface (R_ave = 0.436 with R_σ = 0.033). The performance of the uncoated PS samples revealed R_ave = 0.205 with R_σ = 0.078, and the RSSP samples manifested R_ave = 0.090 with R_σ = 0.003. The AR coating significantly improved the performance of the reference and the RSSP textured surfaces: reference sample, (R_ave = 0.251 with R_σ = 0.040; RSSP samples, (R_ave = 0.024 with R_σ = 0.017). The AR coating did not improve the mid-infrared optical performance of the PS samples; however, the R characteristics for the 0.5 ≤ λ ≤ 2.5 μm portion of the optical spectrum were reduced by more than 50%.     

Exploiting optical properties of P3HT:PCBM films for organic solar cells with semitransparent anode

In this study, we demonstrate optical properties of multilayer system in an organic solar cell based on poly (3-hexylthiophene) (P3HT) and 6,6-phenyl C61-butyric acid methyl ester (PCBM) with semitransparent anode through thermal annealing effect. The optical absorption is enhanced via optimizing annealing treatment which further elevates near-field electric field amplitude. The electric field amplitude at the interface (active layer/semitransparent anode) is enhanced after thermal annealing corresponding to effective absorption near to semitransparent anode. Moreover, the thickness of the active layer is optimized via optical thin-film model for enhancing the organic solar cell efficiency.     

Synthesis by an ionic liquid-assisted method and optical properties of nanoflower Y2O3

Flower-like Y₂O₃ nano-/microstructured phosphors without metal activators have successfully been fabricated by an ionic liquid (IL)-assisted method involving temperature (600 °C) annealing. In this paper, the effect of IL concentration on the morphology of the product has been investigated. The IL plays a crucial role in the formation of various morphologies of Y₂O₃. The structural and morphological features of the obtained samples have been characterized by means of X-ray powder diffraction (XRD) analysis, photoluminescence spectra (PL), Fourier-transform infrared (FT-IR) spectra and X-ray photoelectron spectra (XPS). The photoluminescence spectra of the products exhibit an intense bluish-white emission (ranging from 405 to 430 nm and centered at 418 nm). The luminescent mechanisms have been ascribed to the carbon impurities in the Y₂O₃ host. The effect of the ILs cation and the counter anions on the Y₂O₃ morphology of these nanostructures was studied experimentally. It was observed that Y₂O₃ morphology and PL of these nanostructures were strongly influenced by the type of cation and anion. As the length of the subsidiary chain of cation section of IL (imidaziole ione) reduces, the thickness of the nano-sheets increases. It is expected that the present method may easily be extended to similar nano-/microstructures of other oxide materials. Such investigations are currently underway.     

Enhanced dielectric,ferroelectric and optical properties of lead free (K0.17Na0.83)NbO3 ceramic with WO3 addition

Polycrystalline lead-free ceramics (K_0.17Na_0.83)NbO₃ + x wt.% WO₃; (x = 0, 1, 3 and 5) have been synthesized via solid state reaction method. X-ray diffraction pattern at room temperature indicates the formation of pure perovskite phase with monoclinic structure for all samples. Dielectric constant versus temperature measurements shows an increase in dielectric constant with a shift in Curie temperature (T_C) toward higher temperature side. Remnant polarization (P_r) is found to be enhanced and reached upto 24 μC/cm² for x = 5 wt.% WO₃ from 12.5 μC/cm² for pure (K_0.17Na_0.83)NbO₃ ceramic. The value of coercive field (E_c) decreases with increasing wt.% of WO₃. From optical band gap study, we found blue shift in the band gap of (K_0.17Na_0.83)NbO₃ with increasing concentration of WO₃.     

χ measurements and optical limiting studies of 2-chloro-5-nitro-N′-[(1E)-phenylmethylidene] benzohydrazide with substituents

The nonlinear optical properties of hydrazones substituted with different donor groups were studied using single beam Z-scan technique with nanosecond laser pulses at 532 nm. The nonlinear response in these molecules was found to increase with increase in the donor strength of the substituted group. The χ⁽³⁾ value of these molecules is found to be of the order of 10⁻¹³ esu. The nonlinear refractive index (n₂) of the samples is found to be negative and the largest value of n₂ obtained for the strong donor-substituted molecule is −8.83 × 10⁻¹¹ esu. All samples show good optical limiting behavior at 532 nm. The best optical limiting behavior was observed with the molecule substituted by a strong electron donor.     

Third-order nonlinear optical properties of Bi2S3 nanocrystals doped in sodium borosilicate glass studied with Z-scan technique

The third-order nonlinear optical properties of Bi₂S₃ nanocrystals doped in sodium borosilicate glass are measured by Z-scan technique. The microstructures of the glass are characterized by means of X-ray diffraction, transmission electron microscopy, scanning transmission electron microscopy, energy dispersion X-ray spectra, and high-resolution transmission electron microscopy. The results show that the Bi₂S₃ nanocrystals ranging from 10 to 30 nm are determined to be of the orthorhombic crystalline phase, and the third-order optical nonlinear refractive index γ, absorption coefficient β, and susceptibility χ⁽³⁾ of the glass are determined to be 2.56 × 10⁻¹⁶ m² W⁻¹, 4.13 × 10⁻¹⁰ mW⁻¹, and 1.43 × 10⁻¹⁰ esu, respectively.     

Investigation of optical and compositional properties of thin SiNx:H films with an enhanced growth rate by high frequency PECVD method

Hydrogenated thin silicon nitride (SiN_x:H) films were deposited by high frequency plasma enhanced chemical vapor deposition techniques at various NH₃ and SiH₄ gas flow ratios [R = NH₃/(SiH₄ + NH₃)], where the flow rate of NH₃ was varied by keeping the constant flow (150 sccm) of SiH₄. The deposition rate of the films was found to be 7.1, 7.3, 9 and 11 Å/s for the variation of R as 0.5, 0.67, 0.75 and 0.83, respectively. The films were optically and compositionally characterized by reflectance, photoluminescence, infrared absorption and X-ray photoelectron spectroscopy. The films were amorphous in nature and the refractive indices of the films were varied between 2.46 and 1.90 by changing the gas flow ratio during the deposition. The PL peak energy was increased and the linear band tails become broad with the increase in R. The incorporation of nitrogen takes place with the increase in R.