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RevMexAA (Serie de Conferencias), 42, 126–126 (2013)

MEGARA DETECTOR TEST BENCH AT LICA-UCM

S. M. Tulloch,1 M. L. Garcıa-Vargas,1 M. Maldonado,1 J. Zamorano,2 A. Gil de Paz,2 J. Gallego,2

E. Carrasco,3 J. M. Vılchez,4 and F. M. Sanchez-Moreno5

LICA (Laboratorio de InstrumentacionCientıfica Avanzada) is an initiative of theCampus de Excelencia Internacional of UCM.Among the facilities within LICA, a new lab-oratory has been assigned to MEGARAproject for subsystem tests and AIV. Thispaper presents the current facilities in-stalled at LICA for detector characterization,which will be used to test and characterizeMEGARA detectors.

The LICA laboratory is sufficiently well equippedto carry out a wide range of integration and testingtasks associated with cryogenic optical detectors. Itcontains a 2.5 × 1.5 m optical table, half of whichis occupied by a CCD test bench capable of provid-ing flat-field illumination and artificial star imagesas well as the projection of test patterns. At theheart of this system is a programmable light sourcebased on the Oriel Cornerstone 260 monochroma-tor. A PC running LabView controls this monochro-mator and two filter wheels associated with it. A20W quartz-halogen lamp provides the broad bandinput. Any desired illumination wavelength between370 and 1000 nm can be selected using the LabViewGUI. Figure 1 show the monochromator light source.Flat field illumination is obtained by passing themonochromator output through an Oriel integrat-ing sphere. This sphere has an internal baffle thatallows the exit port to be placed in-line with (i.e.180◦ away from) the entrance port. This simplifiesthe design of the optical bench and makes the mostof the limited space available. The CCD under testneeds to be placed 1m distant from the integratingsphere to improve the illumination uniformity. Thisspace is occupied by a 1m long optical rail on whichadditional optical elements can be placed. By plac-ing a pinhole aperture over the spheres exit port andthen mounting two optical doublets on this rail, anartificial star image can be projected onto the CCD.This optical delta function is extremely useful for di-agnosing charge transfer problems within the CCD.

1FRACTAL SLNE, Madrid, Spain (smt@qucam.com).2UCM, Madrid, Spain).3INAOE, Mexico.4IAA, Granada, Spain.5UPM, Madrid, Spain.

Fig. 1. The monochromator, light source and filter

wheels that form the heart of the CCD test bench.

Quantum efficiency (QE) measurements can alsobe performed in “diode mode” where the CCD isoperated as if it were a simple single-element pho-todiode and its current measured using a Keithley6845 Picoammeter. The CCD current is then com-pared with that generated using an NPL-calibratedHamamtsu photodiode to yield the CCD’s QE.

In order to progress with the LICA laboratoryin the absence of the final MEGARA science CCDsit was decided to build two test cameras using a4k × 4k pixel E2VCCD230. This CCD is almostidentical to, although much cheaper than, the pro-posed science device (it is thick, front-side illumi-nated and in a ceramic package) and will allow usto both commission the CCD test bench and to de-velop MEGARA detector cabling and data acquisi-tion system software well in advance of science-CCDdelivery. The first of these cameras has already beenbuilt. It is of a simple, un-cooled design and has al-lowed verification of the proposed MEGARA cablingand controller code. Its IMO design allows imagingat room temperature, although with high levels ofdark current. The second camera will be built in anIR Labs cryostat and cooled to 170K using the Cry-otiger cooler. It will permit higher-quality imagingand full commissioning of the CCD test bench.

The laboratory also contains a Pfeiffer HiCube80turbo-pump, a 2-channel Lakeshore 325 temperaturecontroller, a Pfeiffer vacuum gauge, an ARC CCDcontroller and the UCAM data acquisition system.

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