RDI’s CMOS_8M system uses an array of large CMOS sensors to create a image area 282 mm x 295 mm with 8.3 million pixels. Each pixel has an active area of 100 mm2. Scattered x-rays from the sample are converted into visible light with a Gd2O2S:Tb phosphor screen and the light is then transferred to the CMOS sensor with a thin fiber optic plate. The images are continuous with no gaps and no geometry correction factor needs to be applied to the images.
A special feature of CMOS sensors compared to CCD detectors is that individual pixels of the sensor can be readout while all the other pixels are acquiring data. The total read time for the detector is only 0.033 seconds. This allows the imaging system to be used for shutter-less crystallography where a series of images are collected as the crystal sample is smoothly rotated. Each frame is usually taken with a 0.1 deg rotation of the crystal and a complete crystal rotation of 180 or 360 degrees. At an x-ray synchrotron an exposure time of 0.04 to 0.2 seconds per frame is used. Therefore a 180 degreee dataset is completed in 72 to 180 seconds.
With our system images frames are acquired with an crystal oscillation range of 0.1 deg and a short exposure time while with most CCD systems images are acquired with an oscillation range of 0.5 -1.0 deg and longer exposure times per frame. Images from our system can be added to simulate the data from a conventional CCD system. The data quality and dynamic range from our system are as good or better than that from a CCD system. In addition, when the CMOS images are used directly by analysis programs they give improved positioning accuacy of the diffraction peaks which results in higher resolution of the final crystal structure.
The detector is read out using a CameraLink interface into a fast Intel PC system with 64 Gbybtes of memory and an SSD drive and running Windows 7. Diffraction data collected with this system can be directly analyzed with standard analysis programs (XDS, HKL2000, MOSFLM, D*Trek, etc.). The data acquisition software is fully functional with the EPICS control system. Software can be provided to allow control of the detector with other software.The system comes with a 40 Tbyte file server and a second fast PC. This enables file storage for many datasets and simultaneous rapid anlysis of datasets while they are acquired by the other computer.
Here are the detailed specifications for the CMOS_1M system.
|Active area (mm)||282 x 295|
|Image size in pixels||2820 x 2950 pixels (8.3 x 106 pixels)|
||100.1 x 100.1|
|Phosophor (optimized for 1 Angstrom)||Gd2O2S:Tb phosophor plate|
|Detector window||Aluminized mylar or Beryllium|
|Spatial Resolution (FWHM) microns||100|
|Dark current (e/pixel/sec)||1|
|Read noise (electrons)||175|
|Signal from one
12 keV photon (electrons)
temperature (deg C)
with external water chiller|
|Readout time (sec)
readout and acquisition)|
||41 wide x 50 high
x 10 thick|
|Detector to PC
|Data Acquisition Computer system
||64 Gbyte Intel PC with
SSD drive using Windows 7|
|Analysis Computer system
||64 Gbyte Intel PC with
|File Storage System
||40 Tbyte with 10 Gbyte Ethernet
Front view of detector Side View  Rear view