Manuel Martinez

ISPI: a wide-field NIR imager for the CTIO Blanco 4-m telescope

The Infrared Side Port Imager ISPI is a facility infrared imager for the CTIO Blanco 4-meter telescope. ISPI has the following capabilities: 1-2.4 micron imaging with an 2K x 2K HgCdTe array, 0.3 arcsec/pixel sampling matched to typical f/8 IR image quality of ~0.6 arcsec and a 10.5 x 10.5 arcmin field of view. First light with ISPI was obtained on September 24 2002, and since January 2003 ISPI has been in operation as a common user instrument. In this paper we discuss operational aspects of ISPI, the behavior of the array and we report on the performance of ISPI during the first one and half year of operation.

A modern approach to upgrading the telescope control system of the CTIO Blanco 4-m telescope

In preparation for the arrival of the Dark Energy Camera (DECam) at the CTIO Blanco 4-m telescope, both the hardware and the software of the Telescope Control System (TCS) have been upgraded in order to meet the more stringent requirements on cadence and tracking required for efficient execution of the Dark Energy Survey1. This upgrade was also driven by the need to replace obsolete hardware, some of it now over half a century old. In this paper we describe the architecture of the new mount control system, and in particular the method used to develop and implement the servo-driver portion of the new TCS. This portion of the system had to be completely rethought, when an initial approach, based on commercial off the shelf components, lacked the flexibility needed to cope with the complex behavior of the telescope. Central to our design approach was the early implementation of extensive telemetry, which allowed us to fully characterize the real dynamics of the telescope. These results then served as input to extensive simulations of the proposed new servo system allowing us to iteratively refine the control model. This flexibility will be important later when DECam is installed, since this will significantly increase the moving mass and inertia of the telescope. Based on these results, a fully digital solution was chosen and implemented. The core of this new servo hardware is modern cRIO hardware, which combines an embedded processor with a high-performance FPGA, allowing the execution of LabVIEW applications in real time.

The Blanco Telescope and its instruments: a status report

In recent years the V. M. Blanco 4-m telescope at Cerro Tololo Inter-American Observatory (CTIO) has been renovated for use as a platform for a completely new suite of instruments: DECam, a 520-megapixel optical imager, COSMOS, a multi-object optical imaging spectrograph, and ARCoIRIS, a near-infrared imaging spectrograph. This has had considerable impact, both internally to CTIO and for its wider community of observers. In this paper, we report on the performance of the renovated facility, ongoing improvements, lessons learned during the deployment of the new instruments, how practical operations have adapted to them, unexpected phenomena and subsequent responses. We conclude by discussing the role for the Blanco telescope in the era of LSST and the new generation of extremely large telescopes.

Design updates and status of the fourth generation TripleSpec spectrograph

TripleSpec 4 (TS4) is a near-infrared (0.8um to 2.45um) moderate resolution (R ~ 3200) cross-dispersed spectrograph for the 4m Blanco Telescope that simultaneously measures the Y, J, H and K bands for objects reimaged within its slit. TS4 is being built by Cornell University and NOAO with scheduled commissioning in 2015. TS4 is a near replica of the previous TripleSpec designs for Apache Point Observatorys ARC 3.5m, Palomar 5m and Keck 10m telescopes, but includes adjustments and improvements to the slit, fore-optics, coatings and the detector. We discuss the changes to the TripleSpec design as well as the fabrication status and expected sensitivity of TS4.

Multi-color laser source for STED microscopy

We report on a pulsed laser source whose wavelength can be switched between 585 nm, 600 nm, and 616 nm. The pulses are approximately 1 nsec long, the repetition rate is 20 MHz, and the pulse energies are 25 to 50 nJ. The laser source uses a laser diode seed and a series of Yb-doped fiber amplifiers to generate pulsed light at 1060 nm. The 1060 nm light is Raman-shifted in ordinary undoped fiber, then converted to the visible using MgO-doped periodically poled lithium niobate (PPLN). In general, the spectrum of such Raman-shifted light is too broad to be efficiently frequency-converted by PPLN. To overcome this problem, we have used narrow band fiber Bragg gratings to create a dual-wavelength fiber Raman laser. The 1060 nm light is first launched into a length of passive fiber, where the first Raman wavelength is generated. This (broad spectrum) light then synchronously pumps the fiber Raman laser, which supports the second and third Raman wavelengths simultaneously. Either of these wavelengths can be frequency doubled, or the two can be frequency summed, to create any of three visible colors. The PPLN crystal accordingly has three poling regions, and the color produced can be selected by indexing the crystal. The final output is suitable for high speed STED microscopy.

Liquid crystal lens array for 3D microscopy and endoscope application

In this paper, we demonstrate two liquid crystal (LC) lens array devices for 3D microscope and 3D endoscope applications respectively. Compared with the previous 3D biomedical system, the proposed LC lens arrays are not only switchable between 2D and 3D modes, but also are able to adjust focus in both modes. The multi-function liquid crystal lens (MFLC-lens) array with dual layer electrode has diameter 1.42 mm, which is much smaller than the conventional 3D endoscope with double fixed lenses. The hexagonal liquid crystal micro-lens array (HLC-MLA) instead of fixed micro-lens array in 3D light field microscope can extend the effective depth of field from 60 um to 780 um. To achieve the LC lens arrays, a high-resistance layer needs to be coated on the electrodes to generate an ideal gradient electric-field distribution, which can induce a lens-like form of LC molecules. The parameters and characteristics of high-resistance layer are investigated and discussed with an aim to optimize the performance of liquid crystal lens arrays.

Cerro Tololo Inter-American Observatory, Victor M. Blanco 4-m Telescope: an upgrade to the telescope control system

The CTIO V. M. Blanco 4-m telescope is to be the host facility for the Dark Energy Survey (DES), a large area optical survey intended to measure the dark energy equation of state parameter, w. The survey is expected to use ~30% of the telescope time over 5 years and use a new 520 megapixel CCD prime focus imaging system: the Dark Energy Camera (DECam). The Blanco telescope will also be the southern hemisphere platform for NEWFIRM, a large area infrared imager currently being commissioned at the Mayall Telescope at KPNO. As part of its normal cycle of continuing upgrades and in preparation for the arrival of these new instruments, the Blanco telescope control system (TCS) will be upgraded to provide a modern platform for observations and maximize the efficiency of survey operations. The upgraded TCS will be based on that used at the SOAR telescope and will be a prototype of the TCS to be used by LSST. It will be optimized for programmed and queued survey observations, will provide extended real-time telemetry of site and facility characteristics, and will incorporate a distributed observer interface allowing for on- and off-site observations and real time quality control. Hardware modifications will include the use of absolute tape encoders and a modern servo control and power driver systems.

Multidimensional optical sensing and imaging for displays, computational imaging, optical security, and healthcare

In this invited paper, we present an overview of our recently published work on 3D imaging, visualization and displays, including optical security using quantum imaging principles, 3D microscopy, healthcare, automated disease identification with 3D imaging, fatigue free augmented reality 3D glasses, and optical security and authentication using photon counting for IC inspection, polarimetric photon counting 3D imaging, and 3D human gesture recognition.

SOAR Telescope seismic performance II: seismic mitigation

We describe design modifications to the SOAR telescope intended to reduce the impact of future major earthquakes, based on the facility’s experience during recent events, most notably the September 2015 Illapel earthquake. Specific modifications include a redesign of the encoder systems for both azimuth and elevation, seismic trigger for the emergency stop system, and additional protections for the telescope secondary mirror system. The secondary mirror protection may combine measures to reduce amplification of seismic vibration and “fail-safe” components within the assembly. The status of these upgrades is presented.

A new Cassegrain calibration lamp unit for the Blanco Telescope

The f/8 RC-Cassegrain Focus of the Blanco Telescope at Cerro Tololo Inter-American Observatory, hosts two new instruments: COSMOS, a multi-object spectrograph in the visible wavelength range (350 – 1030nm), and ARCoIRIS, a NIR cross-dispersed spectrograph featuring 6 spectral orders spanning 0.8 – 2.45μm. Here we describe a calibration lamp unit designed to deliver the required illumination at the telescope focal plane for both instruments. These requirements are: (1) an f/8 beam of light covering a spot of 92mm diameter (or 10 arcmin) for a wavelength range of 0.35μm through 2.5μm and (2) no saturation of flat-field calibrations for the minimal exposure times permitted by each instrument, and (3) few saturated spectral lines when using the wavelength calibration lamps for the instruments. To meet these requirements this unit contains an adjustable quartz halogen lamp for flat-field calibrations, and one hollow cathode lamp and four penray lamps for wavelength calibrations. The wavelength calibration lamps are selected to provide optimal spectral coverage for the instrument mounted and can be used individually or in sets. The device designed is based on an 8-inch diameter integrating sphere, the output of which is optimized to match the f/8 calibration input delivery system which is a refractive system based on fused-silica lenses. We describe the optical design, the opto-mechanical design, the electronic control and give results of the performance of the system.