STFC Engineers have developed a CMOS detector with the ability to detect rapid increases in incident radiation within a single exposure period. This functionality makes the detector particularly useful in the detection of sudden external event, while not limiting any normal uses.

DESCRIPTION

Normal CMOS or CCD detectors do not give any information as to how the incident radiation changes over the exposure period, for example whether the radiation is a steady value or whether it is subject to a sudden increase over the period.

The new CMOS detector has the ability overcome this limitation by storing a time value in a memory every time the amplitude of the sensor output signal crosses a reference voltage in the typical comparator in such detectors. Such a cross of amplitude is considered a hit. By providing multiple memories and resetting the pixel immediately after each hit, multiple hits can be detected per frame. Further modifications to the reference voltage, for instance by changing it linearly, logarithmically or by other methods, greater resolution can be added to the detection of hits. Lastly, hit flag generators can be added which will differentiate between pixels that have interesting information and those that do not, and only the former may be read out. This further increases the speed of the detector by saving on readout time.

INNOVATIONS

• A comparator being able to change its output state at the point in time when amplitude of output signal crosses reference voltage, and recording the time in a memory.
• A hit flag generator which distinguishes pixels with hits and the ones without.

ADVANTAGES

• Ability to record changes in incident radiation during one frame or exposure
• MHz to GHz event rates will be possible before event pile up, orders of magnitude faster than current commercial CCD based readout.
• A unique ability to time tag events to 10 nanosecond accuracy provides a means to time events for time of flight measurements and correlation measurements not possible with current CCD or CMOS array sensors.
• Reduced data readout and analysis overheads in photon, ion and electron imaging applications, as well as improved SNR.

DOMAIN OF APPLICATION