166 research outputs found
Overview of the spectrometer optical fiber feed for the Habitable-zone Planet Finder
The Habitable-zone Planet Finder (HPF) is a highly stabilized fiber fed
precision radial velocity (RV) spectrograph working in the Near Infrared (NIR):
810 - 1280 nm . In this paper we present an overview of the preparation of the
optical fibers for HPF. The entire fiber train from the telescope focus down to
the cryostat is detailed. We also discuss the fiber polishing, splicing and its
integration into the instrument using a fused silica puck. HPF was designed to
be able to operate in two modes, High Resolution (HR- the only mode mode
currently commissioned) and High Efficiency (HE). We discuss these fiber heads
and the procedure we adopted to attach the slit on to the HR fibers.Comment: Presented at 2018 SPIE Astronomical Telescopes + Instrumentation,
Austin, Texas, USA. 18 pages, 25 figures, and 2 table
Ghosts of NEID's Past
The NEID spectrograph is a R 120,000 resolution fiber-fed and highly
stabilized spectrograph for extreme radial velocity (RV) precision. It is being
commissioned at the 3.5 m WIYN telescope in Kitt Peak National Observatory with
a desired instrumental precision of better than 30 \cms{}. NEID's bandpass of
380 -- 930 nm enables the simultaneous wavelength coverage of activity
indicators from the Ca HK lines in the blue to the Ca IR triplet in the IR. In
this paper we will present our efforts to characterize and mitigate optical
ghosts in the NEID spectrograph during assembly, integration and testing, and
highlight several of the dominant optical element contributors such as the
cross dispersion prism and input optics. We shall present simulations of the
2-D spectrum and discuss the predicted ghost features on the focal plane, and
how they may impact the RV performance for NEID. We also present the mitigation
strategy adopted for each ghost which may be applied to future instrument
designs. This work will enable other instrument builders to potentially avoid
some of these issues, as well as outline mitigation strategies.Comment: Conference Proceeding from SPIE Astronomical Telescopes +
Instrumentation (2020): 12 page
The NEID spectrometer: fibre injection system design
NEID is a high resolution echelle spectrograph designed to enable extremely precise Doppler radial velocity observations of stars in the 380-930nm wavelength range1. It has recently been installed at the 3.5m WIYN telescope at Kitt Peak National Observatory, and is currently being commissioned. The design is based on a white pupil layout with a monolithic parabolic primary mirror and a 195mm pupil size on the R4 Echelle grating. Here we describe the optical and mechanical design, assembly, and alignment of the fiber injection system which converts the native focal ratio of the sky, calibration, and science fibers to the focal ratio required to form the 195mm collimated beam
Ultra-Stable Environment Control for the NEID Spectrometer: Design and Performance Demonstration
Two key areas of emphasis in contemporary experimental exoplanet science are
the detailed characterization of transiting terrestrial planets, and the search
for Earth analog planets to be targeted by future imaging missions. Both of
these pursuits are dependent on an order-of-magnitude improvement in the
measurement of stellar radial velocities (RV), setting a requirement on
single-measurement instrumental uncertainty of order 10 cm/s. Achieving such
extraordinary precision on a high-resolution spectrometer requires
thermo-mechanically stabilizing the instrument to unprecedented levels. Here,
we describe the Environment Control System (ECS) of the NEID Spectrometer,
which will be commissioned on the 3.5 m WIYN Telescope at Kitt Peak National
Observatory in 2019, and has a performance specification of on-sky RV precision
< 50 cm/s. Because NEID's optical table and mounts are made from aluminum,
which has a high coefficient of thermal expansion, sub-milliKelvin temperature
control is especially critical. NEID inherits its ECS from that of the
Habitable-zone Planet Finder (HPF), but with modifications for improved
performance and operation near room temperature. Our full-system stability test
shows the NEID system exceeds the already impressive performance of HPF,
maintaining vacuum pressures below Torr and an RMS temperature
stability better than 0.4 mK over 30 days. Our ECS design is fully open-source;
the design of our temperature-controlled vacuum chamber has already been made
public, and here we release the electrical schematics for our custom
Temperature Monitoring and Control (TMC) system.Comment: Accepted for publication in JATI
Stellar Spectroscopy in the Near-infrared with a Laser Frequency Comb
The discovery and characterization of exoplanets around nearby stars is
driven by profound scientific questions about the uniqueness of Earth and our
Solar System, and the conditions under which life could exist elsewhere in our
Galaxy. Doppler spectroscopy, or the radial velocity (RV) technique, has been
used extensively to identify hundreds of exoplanets, but with notable
challenges in detecting terrestrial mass planets orbiting within habitable
zones. We describe infrared RV spectroscopy at the 10 m Hobby-Eberly telescope
that leverages a 30 GHz electro-optic laser frequency comb with nanophotonic
supercontinuum to calibrate the Habitable Zone Planet Finder spectrograph.
Demonstrated instrument precision <10 cm/s and stellar RVs approaching 1 m/s
open the path to discovery and confirmation of habitable zone planets around
M-dwarfs, the most ubiquitous type of stars in our Galaxy
Overview of the spectrometer optical fiber feed for the habitable-zone planet finder
The Habitable-zone Planet Finder (HPF) is a highly stabilized fiber fed precision radial velocity (RV) spec- trograph working in the Near Infrared (NIR): 810 – 1280 nm. In this paper we present an overview of the preparation of the optical fibers for HPF. The entire fiber train from the telescope focus down to the cryostat is detailed. We also discuss the fiber polishing, splicing and its integration into the instrument using a fused silica puck. HPF was designed to be able to operate in two modes, High Resolution (HR- the only mode mode currently commissioned) and High Efficiency (HE). We discuss these fiber heads and the procedure we adopted to attach the slit on to the HR fibers
Optimizing microsurgical skills with EEG neurofeedback
Background
By enabling individuals to self-regulate their brainwave activity in the field of optimal performance in healthy individuals, neurofeedback has been found to improve cognitive and artistic performance. Here we assessed whether two distinct EEG neurofeedback protocols could develop surgical skill, given the important role this skill plays in medicine.
Results
National Health Service trainee ophthalmic microsurgeons (N = 20) were randomly assigned to either Sensory Motor Rhythm-Theta (SMR) or Alpha-Theta (AT) groups, a randomized subset of which were also part of a wait-list 'no-treatment' control group (N = 8). Neurofeedback groups received eight 30-minute sessions of EEG training. Pre-post assessment included a skills lab surgical procedure with timed measures and expert ratings from video-recordings by consultant surgeons, together with state/trait anxiety self-reports. SMR training demonstrated advantages absent in the control group, with improvements in surgical skill according to 1) the expert ratings: overall technique (d = 0.6, p < 0.03) and suture task (d = 0.9, p < 0.02) (judges' intraclass correlation coefficient = 0.85); and 2) with overall time on task (d = 0.5, p = 0.02), while everyday anxiety (trait) decreased (d = 0.5, p < 0.02). Importantly the decrease in surgical task time was strongly associated with SMR EEG training changes (p < 0.01), especially with continued reduction of theta (4–7 Hz) power. AT training produced marginal improvements in technique and overall performance time, which were accompanied by a standard error indicative of large individual differences. Notwithstanding, successful within session elevation of the theta-alpha ratio correlated positively with improvements in overall technique (r = 0.64, p = 0.047).
Conclusion
SMR-Theta neurofeedback training provided significant improvement in surgical technique whilst considerably reducing time on task by 26%. There was also evidence that AT training marginally reduced total surgery time, despite suboptimal training efficacies. Overall, the data set provides encouraging evidence of optimised learning of a complex medical specialty via neurofeedback training
The NEID spectrometer: fibre injection system design
NEID is a high resolution echelle spectrograph designed to enable extremely precise Doppler radial velocity observations of stars in the 380-930nm wavelength range1. It has recently been installed at the 3.5m WIYN telescope at Kitt Peak National Observatory, and is currently being commissioned. The design is based on a white pupil layout with a monolithic parabolic primary mirror and a 195mm pupil size on the R4 Echelle grating. Here we describe the optical and mechanical design, assembly, and alignment of the fiber injection system which converts the native focal ratio of the sky, calibration, and science fibers to the focal ratio required to form the 195mm collimated beam
Consensus on the reporting and experimental design of clinical and cognitive-behavioural neurofeedback studies (CRED-nf checklist)
Neurofeedback has begun to attract the attention and scrutiny of the scientific and medical mainstream. Here, neurofeedback researchers present a consensus-derived checklist that aims to improve the reporting and experimental design standards in the field.</p
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