Frame Interval Control Technique for High-Frequency Electric Field Imaging by Equivalent-Time Sampling

We propose an equivalent-time sampling method with controlled frame spacing to improve the intermediate frequency of field imaging systems. Simple equivalent-time sampling with a constant frame interval detects frequency components other than those to be observed. We present a method that cancels frequency components other than the frequency to be observed by lengthening the frame interval by 1/4 cycle every four frames instead of keeping it constant. We show that only the signal of the frequency to be observed can be detected by an image sensor. We also apply this method to electric field imaging.