PixCellent Ltd.,Capella data sheet

The Capella family of cooled CCD imaging systems

Features:

Programmable readout rate from 500kHz to 8MHz
High sensitivity
14 or 12-bit wide dynamic range (up to 16384:1)
Runs CCDs with 4096 x 4096 pixels down to 80 x 80 pixels
No image retention, lag or distortion
High tolerance to over-exposure
Powerful image processing and analysis software running under Microsoft Windows 95/98
Programmable gain allowing full use of the dynamic range of the system
Programmable high-speed binning giving increased readout rate and signal
User-definable readout sub-array from full area to 8x8 pixel area in 8 pixel steps, allowing faster readout of specific areas of interest

Introduction:

PixCellent has used the very latest CCD technology to develop a range of cooled CCD camera systems that can meet the needs of a broad range of imaging applications. Cooled CCD camera systems enable extremely small differences of light intensity to be detected. Consequently, details of very low contrast phenomena can be studied against much brighter backgrounds, without saturation of the higher intensity areas. This ability to detect low contrast images, combined with the high sensitivity and wide dynamic range of the CCD, results in performance figures for cooled CCD cameras far surpassing that of most other imaging systems.
The Capella family is the latest addition to PixCellent's range of cooled CCD imaging systems. As well as providing all the traditional benefits of cooled CCD cameras, the Capella family offers unrivalled high-speed readout capabilities at very low noise levels. This makes it the ideal camera system for real-time imaging applications which require cooled CCD image quality with low noise at high readout speeds (several milion pixels per second). This readout rate is the fastest available for any cooled CCD camera and places the Capella family firmly at the head of its field.

The Capella family of High-Speed CCD Controllers

There are two models in the Capella family which provide a choice of grey level resolution and maximum speed capabilities:

The basic Capella system provides 12-bit digitisation at pixel rates from 500kHz to 8 MHz (maximum of 5.5 MHz with three-phase frame-transfer CCDs).
The Capella + gives 14-bit digitisation at pixel rates from 500kHz to 8 MHz (maximum of 5.5 MHz with three-phase frame-transfer CCDs).

System components

A typical Capella system comprises four basic components:
Camera electronics unit
Cooled CCD camera head
Computer Interface card installed onto the PCI bus of an IBM/PC Pentium class computer
Ultra-Plus or PixCel camera control and imaging software running under Microsoft Windows 95/98, with the necessary interface and display cards for an IBM PC-compatible host computer.
Camera electronics unit: This unit connects to the host computer via a PCI-bus interface card. It interprets instructions sent from the host to control the camera head and returns up to 14-bit digitised image data for processing.

The Capella camera electronics unit is extremely flexible. It can be programmed to operate in fast mode at 8MHz pixel rate or operated at slower readout rates for highest sensitivity and quality. The pixel rate is programmable from approximately 500kHz to 5.5MHz using double-correlated sampling for minimum noise and at 8 MHz for set up in an uncorrelated mode (this mode is only available with Kodak CCDs). Readout noise varies with the pixel rate and CCD type used. Typical figures are shown in the table for a Capella system fitted with various CCDs.
The pixel rate is measured in MHz and defines the time taken for individual pixels to be read out from the CCD. The noise is measured in electrons and is the internal noise level that applies whenever a pixel is read out from the CCD. As the table indicates, at any speed the camera system produces remarkably low readout noise figures. This versatility makes it ideally suited for a wide range of imaging applications.

Table 1: Capella performance figures

Pixel rate Full-frame read time (seconds) Noise (e- RMS, typical)

(MHz) Kodak KAF0400 Kodak KAF1600 EEV CCD37 EEV CCD39 Kodak KAF400 Kodak KAF1300 EEV CCD37 EEV CCD39

8 0.06 0.22 n/a n/a set-up set-up n/a n/a

5.5 0.08 0.32 0.05 0.002 40 40 75 50

4 0.12 0.48 0.07 0.003 25 25 40 40

2 0.22 0.88 0.15 0.005 15 15 20 16

1 0.45 1.8 0.3 0.01 10 10 20 10

0.5 0.88 3.5 0.6 0.02 8 8 8 8

Cooled CCD camera head

For more information on the camera heads and CCDs supported by PixCellent, please refer to the Camera Head and the CCD data sheet and selection guides.

The camera head houses the CCD in a cooled environment. There are two types of head available:

Air-cooled thermoelectric (Peltier) primary cooling with air cooled heat exchangers.
Water-cooled thermoelectric (Peltier) primary cooling with water cooled heat exchangers.

The camera heads are fitted with the CCDs and use the Peltier effect to cool the CCDs down to the appropriate temperature to reduce the dark current in the CCD. The shutter speed on the camera is programmable from 1 millisecond to 4.5 hours in 1 ms steps. However, the shortest useable exposure and the maximum frame repetition rate is dependent on the type of shutter fitted in the camera head. With frame transfer CCD's exposures much less than 1 millisecond are possible with certain CCDs. The CCD37 frame transfer CCD has aminimum integration time of 1 msec, while the CCD39 has a minimum frame time of 10 microsecs.

Additional hardware

An IBM PC-compatible computer is required to control the camera system and to process the resultant images using the selected software package. Minimum hardware requirements are a Pentium class computer with a 1.2 Gbyte hard disk drive, 64MB RAM and expansion slots for the PixCellent PCI interface card. An SVGA card that is supported by Microsoft Windows 95/98 in a 1024x768 (256 colours) mode is also required, with an appropriate monitor and mouse. Optional hardware peripherals that users may require include:

Additional memory; this will allow more images to be kept in memory and enables the computer to run more efficiently. Extra memory is also needed to store images produced by larger CCDs. Remember that the Capella controller is able to generate data at up to 16 MBytes/second continuous and sustained, and that the amount of memory available for image storage should make a significant allowance for operating system (including virtual memory and buffers for disk storage management)and programme storage. Always err on the generous side, particularly as memory is much less expensive these days.
Additional storage media for users who wish to store large numbers of images. Optical discs such as CD-RAM or DVD-RAM, DAT tapes or 1/4" cartridge tapes can all be used with the system
Laser printers and video printers for users who wish to obtain hard-copy printout and copies of their images.

Home:

The pages on this Web Site are Copyright of PixCellent Imaging Ltd., Cambridge, England. Reproduction in part is permitted with acknowledgement to PixCellent Imaging Ltd., and of this Web Site Address (http://www.pixcellent.com/).