We measured the noise equivalent power (NEP) of an ultra-sensitive membrane-isolated transition-edge sensor (TES) designed for the SpicA FAR Infrared instrument (SAFARI) along with several Johnson ...noise Thermometry Devices (JTDs) simultaneously in a "dark" experimental setup. Our goal was to characterize the dark power P D present in our experimental setup and its effect on the measured NEP. By employing resistive attenuators, filters, lossy coaxial connections, and a light-tight box, we reduced P D to 0.25 fW in our setup. For the TES, G was measured to be (325±25) fW/K at T C =78 mK giving an upper-limit expected NEP of (3.5±0.25)×10 -19 W/Hz 1/2 . We measured an actual NEP on the TES equal to (6.5±1.5)×10 -19 W/Hz 1/2 , which is approximately double the expected value and likely due to residual electrical dark power in our setup.
We report a tunable all-fiber bandpass filter based on a short hollow optical fiber serially concatenated between a pair of long-period fiber gratings. With novel core mode blocking in the hollow ...core fiber and its optimal design, the device showed a low insertion loss of 1.5 dB and broad-band passband tuning range of 84.3 nm covering both S- and C-band.
We report an in-line all-fiber bandpass filter based on a hollow optical fiber (HOF) core mode blocker along with a long-period fiber grating (LPG) pair. It is theoretically and experimentally ...confirmed that selective core mode blocking at the HOF region located in the middle of the LPG pair could provide efficient passband channels corresponding to the resonant wavelengths of the LPGs. The filter characteristics in passbands and the nearfield patterns of guided modes in the proposed device are discussed.
A lensed patch cord probe has been made with a ball lens packaged in a metal cylinder. By simply placing a ball lens directly in front of a fiber patch cord, a compact and potentially disposable ...sampling probe for optical coherence tomography (OCT) could be implemented. To achieve a sufficiently long working distance and a good transverse resolution simultaneously, the proper ball lens diameter and the distance between the ball lens and the fiber patch cord were investigated. Experimentally, a working distance of up to 5.2mm, 3dB bandwidth of 2mm, and transverse resolution of 16μm were achieved. With the patch cord probe, a common path swept source OCT system was implemented and used to demonstrate the feasibility as the dedicated probe for dentistry.
We report progress in fabricating ultra-sensitive superconducting transition-edge sensors (TESs) for BLISS. BLISS is a suite of grating spectrometers covering 35–433 μm with
R
∼700 cooled to 50 mK ...that is proposed to fly on the Japanese space telescope SPICA. The detector arrays for BLISS are TES bolometers readout with a time domain SQUID multiplexer. The required noise equivalent power (NEP) for BLISS is NEP=10
−19
W/Hz
1/2
with an ultimate goal of NEP=5×10
−20
W/Hz
1/2
to achieve background limited noise performance. The required and goal response times are
τ
=150 ms and
τ
=50 ms respectively to achieve the NEP at the required and goal optical chop frequency 1–5 Hz. We measured prototype BLISS arrays and have achieved NEP=6×10
−18
W/Hz
1/2
and
τ
=1.4 ms with a Ti TES (
T
C
=565 mK) and NEP∼2.5×10
−19
W/Hz
1/2
and
τ
∼4.5 ms with an Ir TES (
T
C
=130 mK). Dark power for these tests is estimated at 1–5 fW.
Background/Aims: The purposes of this study were to describe restrictions in instrumental activities of daily living (IADL) in mild cognitive impairment (MCI) and to assess different patterns of IADL ...in each MCI subtype. Methods: A total of 566 participants, those not cognitively impaired (NCI; n = 311) and MCI patients (n = 255), 60–94 years old (71.25 ± 6.00), were examined. Neuropsychological tests were administered to participants, and each MCI patient was classified into one of four subtypes. They completed the Barthel ADL and Seoul-IADL (S-IADL) for ADL measures. Results: There was a significant difference between NCI and MCI in terms of total S-IADL scores. ANOVA and a post hoc Dunnett analysis revealed that MCI patients performed significantly worse on four out of a total 15 items (i.e. telephone, transportation, finances and household appliances). ANCOVA showed a significant difference in S-IADL-MCI (4 of 15 items) between NCI and amnestic MCI-multiple domains after adjusting for age, gender, education and Geriatric Depression Scale (F = 4.257, d.f. = 1,556, p = 0.002). Conclusion: These findings suggest that scorings of specific IADL items are different in MCI subjects, and these items can possibly help in the identification of MCI subtypes, especially amnestic MCI-multiple domains.
We describe a novel class of devices based on the nonlinearity of the kinetic inductance of a superconducting thin film. By placing a current-dependent inductance in a microwave resonator, small ...currents can be measured through their effect on the resonator’s frequency. By using a high-resistivity material for the film and nanowires as kinetic inductors, we can achieve a large coefficient of nonlinearity to improve device sensitivity. We demonstrate a current sensitivity of
8
pA/
Hz
, making this device useful for transition-edge sensor (TES) readout and other cutting-edge applications. An advantage of these devices is their natural ability to be multiplexed in the frequency domain, enabling large detector arrays for TES-based instruments. A traveling-wave version of the device, consisting of a thin-film microwave transmission line, is also sensitive to small currents as they change the phase length of the line due to their effect on its inductance. We demonstrate a current sensitivity of
5
pA/
Hz
for this version of the device, making it also suitable for TES readout as well as other current-detection applications. It has the advantage of multi-GHz bandwidth and greater dynamic range, offering a different approach to the resonator version of the device.
PDF
