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For total luminous flux calibration by a sphere-spectroradiometer system in 2π geometry, a new LED-based standard light source (standard LED) covering the full visible wavelength range has been developed. The developed standard LED has sufficient spectral power over the full visible wavelength range using UV-LED dies of different peak wavelengths in combination with red, green and blue phosphors. By evaluating spectrum flatness based on the magnitude of the second derivative, the spectrum of the standard LED was customised to minimise the measurement uncertainty. Properties of the standard LED such as the luminous intensity distribution, stability and reproducibility were also evaluated. The evaluation results indicate that the standard LED has good properties as a standard light source for the 2π total spectral radiant flux scale. Furthermore, the result of an operating current dependence suggests that the standard LED has benefits as a standard source that conventional standard lamps do not have.

In response to the strong demand for a total spectral radiant flux (TSRF) standard from domestic lighting manufacturers, such a scale has been realized in the visible range by means of a relative gonio-spectroradiometric method at the National Metrology Institute of Japan (NMIJ). Our gonio-spectroradiometric method employs spectral irradiance as well as a luminous intensity standard as reference standards. We have investigated several models of quartz-halogen lamps from domestic manufacturers with respect to their stability and decided a set of reference standard lamps for TSRF. Our carefully selected quartz-halogen lamps have sufficient stability as the standard lamp for TSRF after a 100 h seasoning process. The relative expanded uncertainty (k = 2) for realization of the TSRF scale is between 3.1% (visible regions) and 4.1% (near ultraviolet region). We evaluated uncertainties related to the characteristics of the array spectroradiometer using experimental results and found some of those, such as effect of bandpass function, noticeably contributed to the total uncertainty.

This study discusses wavelength dependence of non-linearity of optical fibre power meters (OFPMs). The non-linearity for several kinds of OFPMs was measured at various wavelengths used in optical communication to determine its wavelength dependence. The response of OFPMs was intrinsically linear and the linearity seemed to be wavelength independent for a certain wavelength range that probably meets the conditions that almost all electron-hole pairs generated by incident light reach the space-charge region of a photodiode and contribute to photocurrent. This suggests that linearity calibration at a single or a few wavelength(s) would be sufficient to derive the linearity at arbitrary wavelength around the calibration point(s). The non-linearity of OFPMs appeared when carrier recombination is not negligible during carrier diffusion into the space-charge region, and it was probably wavelength dependent, as it can be described theoretically. It was also found that using a modulated test light source revealed whether the non-linearity measured for a continuous wave (CW) source is an intrinsic one (because of supraresponsivity, photodiode saturation) or range discontinuity.

Photon number resolving detectors based on titanium-transition edge sensors with high speed and high quantum efficiency have been developed for quantum sensors in the fields of quantum information and quantum radiometry. The two devices optimized at wavelengths of interest showed 81% and 64% system detection efficiencies at 850 nm and 1550 nm, respectively. The response speed of the device optimized for a high counting operation is 190 ns, which corresponds to a counting rate over 1 MHz.

The aging characteristics of commercial deuterium lamps not subjected to a pre-aging process were measured. The evaluation of window material degradation showed that the degradation alone cannot completely account for the observed decrease in radiant flux. The variation in the plasma condition of a deuterium lamp was investigated as a possible cause of the decrease. A new measurement method using the cathode box of the deuterium lamp as a probe was used to evaluate the electron temperature of the plasma of the deuterium lamp. The electron temperature was also estimated by a spectroscopic method. The variations in the electron temperatures derived by these two methods were consistent, showing that the average energy loss of electrons exceeds 20% after a 400 h operation. These results suggest that another possible cause for the decrease is the variation in the plasma condition of the deuterium lamp.

The electron storage ring TERAS was used to calibrate the spectral radiance of transfer standard light sources in the ultraviolet (UV) and vacuum ultraviolet (VUV) regions. This calibration system, constructed at the beamline, is an improvement on a prototype system we constructed previously. The new system is simpler and does not require breaking the vacuum of the calibration system. Also, the signal from the transfer standard light source is strong, the conditions of the light sources (synchrotron radiation and transfer standard light source) can be observed directly (it is possible to evaluate the profiles or some parameters of light sources without breaking the vacuum), the polarimeter is improved and the uncertainty due to the polarization effect is expected to be improved. In addition to describing these improvements, we re-examine some uncertainties.

A low temperature scanning synchrotron microscope (LTSSM) has been developed for spatial analysis of superconducting tunnel junction X-ray detectors. One and two-dimensional images of the detector response to X-rays were measured by scanning the junctions kept at a working temperature of about 0.4 K with a highly collimated synchrotron radiation beam. The collimation was performed by inserting a pinhole mounted on a scanning unit into the synchrotron radiation in the range of 3-6 keV. The spatial resolution of the LTSSM is between 5 and 10 micrometer. The present results indicate a large discrepancy between the experimental spatial response and a quasiparticle diffusion and edge-loss model. The LTSSM plays an important role in the development of cryogenic X-ray detectors.

We have constructed a beamline which serves for calibrating transfer standard light sources in the UV and VUV regions. The synchrotron radiation (SR) from the electron storage ring TERAS (750 MeV) is used as a primary standard of spectral radiant-intensity. In the beamline, a deuterium lamp was used for transfer standard light source. The SR is linearly polarized and the deuterium lamp is almost unpolarized, and hence the polarization effect of the optical system in its beamline cannot be neglected. We evaluated the polarization effect of the optical system and calibrated the spectral radiance of a deuterium lamp in the wavelength range 160–310 nm. The uncertainty of the spectral radiance of the calibrated lamp by the polarization effects is estimated to be about ±10%.

For an improvement of the aging characteristic of deuterium lamp, it was tried to exchange its regular window glass material(Type III silica glass) for other glass material(fluorine-doped silica glass). By using fluorine-doped silica glass as a new window material. The spectral irradiance of deuterium lamp was improved maximum 20% in comparison to those with TypeIII silica glass window after 402hours operation. This phenomenon is explained by difference of window material degradation. A cause of degradation is photoabsorption produced by defects which were made by photochemical reaction in the glass.

Undulator radiation was used for detector calibration based on a room-temperature-operated electrical substitution radiometer (ESR) in the wavelength range from 200 to 400 nm. The intense radiation from an undulator was shown to be very suitable for use with a thermal detector such as an ESR which has low responsivity.

It has been demonstrated by Low-Temperature Scanning Synchrotron Microscope that the spatial profiles of Nb/Al/AlOx/Al/Nb detectors are abnormally large in an energy range between 2 and 10 keV, and thus the detectors produce no clear total absorption peaks. Below 2 keV, on the other hand, full illumination experiments have afforded the evidence that the spatial uniformity is significantly improved, for example, an 100 μm square junction has an intrinsic energy resolution of 5.4 eV at 200 eV. These results reconfirm that carefully designed junction detectors with a reasonable size are ideal for energy-dispersive spectroscopy in a soft X-ray range.

We demonstrated a very low-noise, large-area calorimeter based on a micromechanical heat-flow sensor. The input heat flow is transduced to the bimetallic deformation of the sensor, which is observed using a high-resolution fiber optic interferometer. The characteristics of 5-mm-square Si–Al bimetallic micromechanical sensors fabricated using silicon-on-insulator micromachining processes were investigated. We experimentally achieved a heat-detection noise of 12 nW, which is comparable to the best performance of thermopiles. The developed sensor is free of Johnson noise, which constrains the signal-to-noise ratio. In principle, this technique can provide a sub-nanowatt resolution even in air at room temperature.

We have been attempting to establish an absolute scale of spectral radiance in ultraviolet and vacuum ultraviolet regions by using synchrotron radiation as a primary standard light source and also attempting to transfer the absolute scale to an under‐test light source by comparing the under‐test source with synchrotron radiation. The calibration apparatus does not function as ideal comparator because some properties of incident radiation, which are spectral distribution and polarization state, are different between synchrotron radiation and the under‐test light source, and the signal of the apparatus accordingly depends on not only spectral radiant power but also depends on the properties of the incident radiation. We evaluated how the detector signal ratio was affected by the difference both experimentally and theoretically, and also evaluated the uncertainty of the scale transfer caused by the difference.

Imaging diagnosis of superconducting tunnel junction x-ray detectors has been performed by an apparatus called the low-temperature scanning synchrotron microscope (LTSSM) using an x-ray microbeam with a diameter of 5–10 μm originated from synchrotron radiation. Quasiparallel intense synchrotron radiation enables one to obtain the full two-dimensional images of junctions with dimensions of 200×200 μm2 in about 1 h. The LTSSM results indicate that the standard quasiparticle diffusion and edge loss model for the spatial distribution of the junction response to x rays is evidently inadequate for intermediate or large junctions (with respect to a Josephson penetration depth). On this basis, it is argued that the models proposed for the signal creation and loss mechanism should be reconsidered.

A transition edge sensor (TES) is one of superconducting photon detectors, which has a photon number resolving ability in light pulses. The TES device is a kind of calorimeters operated at an extremely low temperature, and the energy of the photons is measured as a resistance change in a superconducting transition region of the TES. The advantages of the TESs are an excellent energy resolution and a high quantum efficiency. However a response speed is limited due to slow thermal recovery time. To overcome this, we fabricated new TES devices which are based on a titanium superconductor. The critical temperature of our titanium films is around 410 mK, which greatly improves the thermal recovery time. The observed decay time constant of response signals to the light pulses is around several hundreds of ns, that make it possible to operate the devices at a counting rate over 1 MHz. The photon number resolving power is 0.35 eV(FWHM) for a 5 μm size device even at the high operating temperature. The system quantum efficiency is 65 % by embedding the TES films in an optical structure with a high reflection dielectric mirror and an anti-reflection coatings fabricated by an ion beam assisted sputtering method. These features are very promising for high speed photon number resolving applications in the quantum information field.

We report on some efforts to improve a quantum efficiency of titanium‐based optical superconducting transition edge sensors using the multi‐layered absorption structure for maximizing photon absorption in the Ti layer. Using complex refractive index values of each film measured by a Spectroscopic Ellipsometry, we designed and optimized by a simulation code. An absorption measurement of fabricated structure was in good agreement with the design and was higher than 99% at optimized wavelength of 1550 nm.

We have been attempting to establish an absolute scale of spectral radiance in ultraviolet and vacuum ultraviolet regions by using synchrotron radiation as a primary standard light source and also attempting to calibrate an under‐test light source by comparing the under‐test source with the primary standard light source. A calibration system consisting of a focusing mirror, a monochromator and a detector was introduced for the calibration. If the efficiency of the calibration system were constant, the calibration could be done only by comparing the detector signals obtained from measuring each of the light sources. However the efficiency of the calibration system differs with each of the light sources because the primary and under‐test light sources differ in terms of polarization state, and the transmittance or reflectance of the optical element depends on incident light polarization and the efficiency of the calibration system, and hence also depends on incident light polarization. Consequently, determining the polarization dependence of the calibration system is necessary for the calibration, as is comparing the detector signals. Furthermore, if the polarization dependence of the focusing mirror or the grating of the monochromator in the calibration system is not uniform, it is necessary to make a map showing the polarization dependence of the calibration system versus the vertical and horizontal angles at which the radiation of each light source enters the calibration system. We evaluated the polarization dependence of the calibration system on the vertical angle and evaluated the uncertainty of the spectral radiance calibration due to the angular distribution.

A beamline which serves for calibrating transfer standard light sources (deuterium lamps, excimer lamps, Xe lamps etc.) in the UV and VUV regions is being constructed. The synchrotron radiation from the electron storage ring TERAS (750 MeV) is used as a primary standard of spectral radiant intensity. In order to use synchrotron radiation as a primary standard, the electron beam and synchrotron radiation beam parameters need to be evaluated. Uncertainties of synchrotron radiation flux evaluated by measurements of the magnetic flux density, the position of the electron orbital plane, the electron beam size and the distance from the synchrotron radiation tangent point to the detector system are expected to be about 0.003, 0.01, 0.05 and 0.1%, respectively.

Spatial uniformity in the response of superconducting tunnel junction detectors (STJ) to photons is a main concern in the development of these devices. Low Temperature Scanning Synchrotron Microscopy (LTSSM) has been used to directly image spatial profiles of the response of Nb-based STJ to X-ray photons. Scanning an X-ray microbeam with a diameter of 5–10 μm enables visualization of the spectroscopic properties of STJ X-ray detectors at an actual working temperature of about 0.4 K. We have found that the inhomogeneity of the junction response strongly depends on the junction size, the bias points, and the strength of applied magnetic field parallel to the insulation barrier. It is proposed that some resonance phenomena in the junction may influence signal creation processes.

We have realized a high-detection-efficiency photon number resolving detector at an operating wavelength of about 850 nm. The detector consists of a titanium superconducting transition edge sensor in an optical cavity, which is directly coupled to an optical fiber using an approximately 300-nm gap. The gap reduces the sensitive area and heat capacity of the device, leading to high photon number resolution of 0.42 eV without sacrificing detection efficiency or signal response speed. Wavelength dependent efficiency in fiber-coupled devices, which is due to optical interference between the fiber and the device, is also decreased to less than 1% in this configuration. The overall system detection efficiency is 98%±1% at wavelengths of around 850 nm, which is the highest value ever reported in this wavelength range.

We compare the results of measurements of the nonlinearity of high-power optical fiber powermeters (OFPMs) by two national metrology institutes (NMIs): the National Institute of Standards and Technology (NIST-USA) and the National Metrology Institute of Japan/National Institute of Advanced Industrial Science and Technology (NMIJ/AIST-Japan) at a wavelength of 1480 nm. The nonlinearity and range discontinuity of a commercial OFPM were measured from 1 mW to 500 mW by use of a superposition method (both laboratories) and from 1 mW to 250 mW by use of a comparison method (NMIJ only). Measurement results showed largest differences of less than 1.6 parts in 10(3), which is within the combined expanded (k = 2) uncertainty for both laboratories.

Density and space potential fluctuations have been studied in electron cyclotron resonance heating (ECRH) plasma of a helical axis stellarator TU Heliac using Langmuir probe techniques. These fluctuations are coherent and global, which can be explained by a drift instability model in cylindrical geometry. A particular fluctuation mode vanishes inside a rational surface. The ratio of this mode, n/m, corresponds to the rotational transform ι/ of this rational surface, (m, n: poloidal, toroidal fluctuation modes, respectively). This phenomenon near the rational surface can also be explained by a drift instability theory.

A new capacitive/resistive probe method for mapping the magnetic surfaces from resistance or capacitance between a magnetic surface and a vacuum vessel was developed and tested. Those resistances and capacitances can be regarded as components of a simple electrical bridge circuit. This method exploits electrical transient response of the bridge circuit for a square pulse. From equiresistance or equicapacitance points, the magnetic surface structure can be deduced. Measurements on the Tohoku University Heliac, which is a small-size standard heliac, show good agreement with numerical calculations. This method is particularly useful for pulse-operated machines.

We have fabricated Niobium-based superconducting single photon detector (Nb-SSPD) for realizing high detection efficiency and fast reset time. The Nb-SSPD consisted of a 7 nm-thick and 200 nm-wide Nb meander line and exhibited the critical temperature and critical current density of 4 K and 4.6×105 A/cm2, respectively. The Nb-SSPD was coupled to an optical fiber, and the reset time of 2.5 ns was observed with illumination of laser pulses at 1550 nm wavelength.

The APMP.PR-S4 comparison of fiber optic power responsivity and nonlinearity at 1550 nm, from 1?mW to 250?mW, was carried out. In total three institutes participated: NMIJ (Japan), PTB (Germany) and NPL (United Kingdom). The measurements started in December 2008 and ended in December 2009. For fiber optic power responsivity, all participants reported their results and all results were used for the intercomparison: no measurement was subject to rejection. For nonlinearity two participants reported their results, therefore only a bilateral comparison was performed. The analysis method was carried out according to the Guidelines for CCPR Comparison Report Preparation and has been accepted by all participants. The reference value of fiber optic power responsivity was calculated using all participants' results. For fiber optic power from 10?mW to 250?mW all participants had unilateral DoE values consistent with their uncertainties at the k = 2 level. For fiber optic power of 1?mW all participants achieved consistency at the k = 3 level. For nonlinearity, the consistency of the measurements at both NMIJ and PTB was achieved with uncertainty at the k = 2 level. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the APMP, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).