Lens mounting techniques for precise radial location of fragile lenses in the NGS2 and Veloce instruments

We present novel methods for mounting lenses in a pair of instruments that presented challenging optical and mechanical requirements. The first instrument is the replacement Natural Guide Star Sensor (NGS2) for CANOPUS at Gemini South, which incorporates an objective consisting of a stack of six lenses mounted in a common bore. A compliant radial spacer was used to eliminate lens decentre resulting from the additional radial clearance required to accommodate differential thermal strains between the low thermal expansion lenses and a common bore. In the same instrument, tangent contact toroidal spacers were deployed in place of traditional conical spacers to further reduce contact stresses in fragile calcium fluoride lens elements. The toroidal faces were specified with a 10µm profile tolerance to avoid possible edge contact between the spacers and lenses. We investigated milling and turning machining processes for the production of the spacers by comparing their results via Coordinate Measuring Machine (CMM) measurements. In the second instrument, Veloce, built for the Anglo-Australian Telescope, a lens decentre requirement of 40µm led us to develop a simple means of in-situ centring adjustment of the cell mounted lens. Physical testing of the finished instruments verified the performance of each of these methods. NGS2 produced images at the factory acceptance test in which 94% of encircled energy was captured by a single 16um detector pixel, surpassing the specification of 80%. Bench testing of Veloce during assembly showed that the adjustment mechanism allowed centring of the lens over a range of +/- 0.1mm with a precision of 5µm

AO corrected satellite imaging from Mount Stromlo

The Research School of Astronomy and Astrophysics have been developing adaptive optics systems for space situational awareness. As part of this program we have developed satellite imaging using compact adaptive optics systems for small (1-2 m) telescopes such as those operated by Electro Optic Systems (EOS) from the Mount Stromlo Observatory. We have focused on making compact, simple, and high performance AO systems using modern high stroke high speed deformable mirrors and EMCCD cameras. We are able to track satellites down to magnitude 10 with a Strehl in excess of 20% in median seeing

Pyxis: A ground-based demonstrator for formation-flying optical interferometry

In the past few years, there has been a resurgence in studies towards space-based optical/infrared interferometry, particularly with the vision to use the technique to discover and characterise temperate Earth-like exoplanets around solar analogues. One of the key technological leaps needed to make such a mission feasible is demonstrating that formation flying precision at the level needed for interferometry is possible. Here, we present $\textit{Pyxis}$, a ground-based demonstrator for a future small satellite mission with the aim to demonstrate the precision metrology needed for space-based interferometry. We describe the science potential of such a ground-based instrument, and detail the various subsystems: three six-axis robots, a multi-stage metrology system, an integrated optics beam combiner and the control systems required for the necessary precision and stability. We end by looking towards the next stage of $\textit{Pyxis}$: a collection of small satellites in Earth orbit.Comment: 27 Pages, 14 Figures, submitted to JATI

A conceptual design study for Subaru ULTIMATE GLAO

We report on the conceptual design study done for the Ground Layer Adaptive Optics system of the ULTIMATE-Subaru project. This is an ambitious instrument project, providing GLAO correction in a square field of view of 14 arcmin on a side, aiming to deliver improved seeing at the near infrared wavelength. Its client instruments are an imager and multi-IFU spectrograph at Cassegrain and a Multi-Object spectrograph at Nasmyth. In this paper, we introduce the ULTIMATE-Subaru project overview and its science case and report the results of the GLAO performance prediction based on the numerical simulation and conceptual design of the wavefront sensor systemThe development of ULTIMATE-Subaru is partly supported by the Japan Society for the Promotion of Science (Grant-in-Aid for Research #17H06129)

Design evolution of the Giant Magellan Telescope Integral Field Spectrograph, GMTIFS

We report the design evolution for the GMT Integral Field Spectrograph, (GMTIFS). To support the range of operating modes – a spectroscopic channel providing integral field spectroscopy with variable spaxel scales, and a parallel imaging channel Nyquist sampling the LTAO corrected field of view - the design process has focused on risk mitigation for the demanding operational tolerances. We summarise results from prototype components, confirming concepts are meeting the necessary specifications. Ongoing review and simulation of the scientific requirements also leads to new demonstrations of the science that will be made possible with this new generation of high performance AO assisted instrumentation

Anger in brain and body: the neural and physiological perturbation of decision-making by emotion

Emotion and cognition are dynamically coupled to bodily arousal: The induction of anger, even unconsciously, can reprioritise neural and physiological resources toward action states that bias cognitive processes. Here we examine behavioural, neural and bodily effects of covert anger processing and its influence on cognition, indexed by lexical decision-making. While recording beat-to-beat blood pressure, the words ANGER or RELAX were presented subliminally just prior to rapid word/non-word reaction-time judgements of letter-strings. Subliminal ANGER primes delayed the time taken to reach rapid lexical decisions, relative to RELAX primes. However, individuals with high trait anger were speeded up by subliminal anger primes. ANGER primes increased systolic blood pressure and the magnitude of this increase predicted reaction time prolongation. Within the brain, ANGER trials evoked an enhancement of activity within dorsal pons and an attenuation of activity within visual occipitotemporal and attentional parietal cortices. Activity within periaqueductal grey matter, occipital and parietal regions increased linearly with evoked blood pressure changes, indicating neural substrates through which covert anger impairs semantic decisions, putatively through its expression as visceral arousal. The behavioural and physiological impact of anger states compromises the efficiency of cognitive processing through action-ready changes in autonomic response that skew regional neural activity

Veloce Rosso: Australia's new precision radial velocity spectrograph

Veloce is an ultra-stable fibre-fed R4 echelle spectrograph for the 3.9 m Anglo-Australian Telescope. The first channel to be commissioned, Veloce ‘Rosso’, utilises multiple low-cost design innovations to obtain Doppler velocities for sun-like and M-dwarf stars at 75,000 spectra over a 580-930 nm range for the Rosso channel. Simultaneous calibration is provided by a single-mode pulsed laser frequency comb in tandem with a traditional arc lamp. A bundle of 19 object fibres ensures full sampling of stellar targets from the AAT site. Veloce is housed in dual environmental enclosures that maintain positive air pressure at a stability of ±0.3 mbar, with a thermal stability of ±0.01 K on the optical bench. We present a technical overview and early performance data from Australia's next major spectroscopic machine

Isotopic dependence of fusion barrier energies in reactions forming heavy elements

The systematic dependence of fusion barrier energies on neutron excess can be determined over a broader range using radioactive nuclei. It is shown that precise measurements with a wide range of stable isotopes are necessary for optimum interpretation o