Advantages of ICCD | disadvantages of ICCD
This page covers advantages and disadvantages of ICCD. It mentions ICCD advantages or benefits and ICCD disadvantages or drawbacks. ICCD stands for Intensified Charge Coupled Device.
What is ICCD?
To overcome limitations of CCD (Charge Coupled Device), ICCD has been developed. It exploits optical amplification provided by image intensifier to overcome the limitations of basic CCD sensor.
It uses image intensifier tube in its design to provide high optical gain and gateable operation. ICCD based devices are used for various applications including spectroscopy, scientific and industrial imaging, medical diagnostics etc. This has become popular at large scale due to development of image intensifier tubes. The image intensifier can operate as very fast optical switch, which captures optical signal in billionths of a second.
ICCD comprises of image intensifier tube coupled with traditional CCD sensor device. Light output of tube is coupled with CCD in two ways viz. using fiber optic coupler and lens coupled. These are the two possible type of constructions in ICCD. Lens coupled type used lens between output of image intensifier and CCD instead of fiber coupler. The figure-1 depicts fiber coupled ICCD type.
The major component in ICCD design is power supply as shown. It generates DC voltage (about 600-900 volts) for MCP (Microchannel Plate) to achieve desired gain. It generates DC voltage (about 4KV-8KV) for phosphor screen. It generates voltage pulses (about 200 Volts) for gated operation of the photocathode.
There are many characteristic features of ICCD which include spectral response, spatial resolution, gating time, repetition rate, sensitivity, noise, dynamic range and frame rate.
The spectral response of ICCD camera is determined based on input window, photocathode materials and photocathode size used in the image intensifier tube. Let us understand merits and demerits of ICCD based on these two types viz. fiber coupled ICCD and lens coupled ICCD.
Benefits or advantages of ICCD
Following are the benefits or advantages of ICCD:
➨Fiber coupled ICCD system is physically very compact and offers low optical distortion levels.
➨High efficient fiber optic coupled ICCD allows operation of image intensifier tube at lower gains. This results in better dynamic range and better performance.
➨Lens coupled offers great flexibility by allowing use of ICCD device in non-intensified mode.
➨ICCD can be viewed as a camera with effectively no read noise. This is due to the fact that image intensifier amplifies the signal and hence CCD section of the camera do not dominate in noise of the camera.
➨They have optical shuttering properties which is real advantage over CCD and EMCCD types.
Drawbacks or disadvantages of ICCD
Following are the drawbacks or disadvantages of ICCD:
➨Lens coupled ICCD is large in physical size, low coupling efficiencies and increased scatter.
➨ ICCD camera has lower resolution compare to CCD camera Recent developments in finer phosphor deposition, reducing gaps and reducing the bore of the Microchannel plates has resulted in much better performance but still resolution is limited to less than 60 line pairs/mm.