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: http://www.sao.ru/drabek/CCDP/TUTORIAL/BackIllum/tutorial-illum-pluto.htm
Дата изменения: Thu Nov 12 12:09:30 1998 Дата индексирования: Tue Oct 2 13:30:37 2012 Кодировка: Поисковые слова: mars |
The following section summarizes the general architecture of the PlutoCCD video rate, back-illuminated, low-light-level CCD as is outlined in Table 2-1. The PlutoCCD CCD is a video rate, low noise, 2048 x 1024 element, 9-micron or 12-micron pixel back-illuminated CCD. Using four high performance on-chip output amplifiers enhances the PlutoCCD CCD’s sensitivity and dynamic range. A high frame rate is maintained by using a Split Frame Transfer CCD design that has an opaque storage region on both the upper quarter and the lower quarter of the CCD array. Unlike interline transfer devices that often block more than 65% of incoming light, the PlutoCCD CCD Split Frame Transfer architecture has 100 percent fill factor, thereby allowing every photon to strike the photo sensitive area of the CCD. This architecture optimizes the data transfer rate of the camera and minimizes image smear. As can be observed from the list of model variations in Table 1.1, the exact configuration of the CCD can easily be optimized for each application’s requirements.
Figure 2-1. PlutoCCD 2048 x 1024 Element Split-Frame Transfer CCD Table 2-1. PlutoCCD CCD Family Architecture
A picture of a Split Frame Transfer version of the PlutoCCD CCD is shown in Figure 2-1. When operating, the charge in the active, optically sensitive region of the CCD is clocked into the two storage regions, and while the signal from the next frame is being integrated, the charge in the storage region is sampled by correlated double sampling circuitry and is then digitized. Low noise, on-chip amplifiers are located on each corner of the CCD. Using four amplifiers decreases the noise equivalent bandwidth of the system and increases sensitivity. Several PlutoIII CCD foundry lots were manufactured and the device performance was measured against the design goals. The high back-illuminated CCD quantum efficiency (greater than 85 percent), combined with multiple low noise amplifiers, results in a system that is ideally suited for low light level imaging applications. The back-illuminated, 2048 x 1024 element, four output amplifier, PlutoCCD CCD is available with an anti-reflective coating that enhances the CCD’s sensitivity in either the ultra-violet (UV), soft x-ray (NO) or visible (VIS) spectral regions. As can be seen in Table 2-2, which documents the performance measured for the design, the 12-micron PlutoCCD CCD achieves less than 5 electrons rms. noise, full well exceeding 240,000 electrons, and linearity better than one percent. Table 2-2. SandboxIII PLUTOIII Performance
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