Performance Summary For 16 Science Grade Vista Modules

Figures 2, 3 and 4 provide a summary of the performance of the 16 science grade VISTA modules. Figure 2 shows array-average QE for the J, H, and K bands. These values reflect the average of all 2048x2048 active pixels on each array. In Figure 3, the QE uniformity is shown for the same modules (sigma/mean in %). All modules meet the VISTA QE requirements in all three spectral bands (J-band: >38%; H- and K-bands: >47%). In addition, all modules meet the QE uniformity requirement of <10% sigma/mean with the exception of the J band on two modules (see Fig. 3). Similar results are shown for dark current in Figure 4. Dark current was measured at 78 K with 500 mV of applied detector bias. Array-average dark currents were generally less than 1e-/sec at 78 K. Other institutions have measured significantly lower dark currents than measured at RVS. For example, Roger Smith [5] at Caltech measured 0.025e-/sec at 79 K on module 19 compared to the RVS value of 0.92e-/sec and Craig McMurtry [6] at the University of Rochester measured a mean dark current of 0.019e-/sec (median dark current was 0.029e-/sec) on module 27 compared to the RVS value of 0.45e-/sec. Roger Smith also measured a MUX glow of 0.04e-/read for the VIRGO MUX.

Mean Q.E. in J, H, and Ks Bands for 16 Science Grade Modules

Mean Q.E. in J, H, and Ks Bands for 16 Science Grade Modules

Figure 2. QE performance summary for the 16 science grade VISTA modules. The VISTA requirement is >38% for the J-band and > 7% for the H- and K-bands.

Figure 2. QE performance summary for the 16 science grade VISTA modules. The VISTA requirement is >38% for the J-band and > 7% for the H- and K-bands.

Q.E. Uniformity in J, H, and Ks Bands for 16 Science Grade Modules

Q.E. Uniformity in J, H, and Ks Bands for 16 Science Grade Modules

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Figure 3. QE sigma/mean performance summary for the 16 science grade VISTA modules. The VISTA requirement is sigma/mean <10% for all three spectral bands.

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Figure 3. QE sigma/mean performance summary for the 16 science grade VISTA modules. The VISTA requirement is sigma/mean <10% for all three spectral bands.

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Mean Dark Current for 16 Science Grade Modules

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Figure 4. Dark current performance summary at 78K for the 16 science grade VISTA modules. The VISTA requirement is <8e-/sec at 77K.

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