Researchers at Japan’s National Institute of Information and Communications Technology (NICT) have developed an RF camera with a measurement bandwidth 10 MHz to 110 GHz, based on the refractive index change of ZnTe crystals, measured with a laser. The new technology could be used in the future to visualize the beam pattern of antennas.
Images are taken at 20,000 fps with a CMOS sensor. To remove noise and make faint signals visible, the images are integrated so that the frame rate becomes equivalent to 10 to 1,000fps. At a frame rate of 1,000fps, it is difficult to see images with the naked eye. So, they are recorded and played back later in slow motion.
The viewing field and pixel count of the exhibited camera are 25 x 25mm and 100 x 100, respectively. The resolution per pixel is 0.25mm. It can be reduced to less than 0.1mm, but the structure has to be changed to make it less than 0.05mm, NICT said.
The resolution of the image to show the intensity supports 256 grayscale in the range from 30 to 40 dB. The image data can be processed with a higher resolution for numerical analysis without displaying images though it will become more difficult to take measures against noise, NICT said. Also, the institute considers it possible to increase the size and the pixel count of the image by, for example, combining crystals.
Currently, the electric field camera only enables to observe the state of a circuit as a movie. But NICT plans to add functions to analyze the image and point out the problems of a circuit by using the image data.
NICT developed the principle of the electric field camera in 2007 and is now looking for a company that is willing to commercialize the technology. Judging from the composition of the camera, its manufacturing cost will be equivalent to those of the highest-end oscilloscopes with a high frequency band. This time, the institute realized the camera using a box measuring 30 x 18 x 18.5cm.
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