Research Of Optical Encoding Imaging System With Data Compression

Ultra-fast imaging is recording the fast-process events,so that people can explore and analyze the micro-world.It requires high temporal resolution and high spatial resolution to ensure higher image quality.Blurred images have no research value for the study of ultrafast processes.The imaging rate of convential image sensors at 30 Hz,which is far from sufficient to imaging the moving process at picosecond.Pump-probe imaging technology and streak camera imaging rate can reach the picosecond,but both have their own limitations,pump-probe imaging technology only satisfied with the repetitive event imaging,and streak camera requires synchronization between the camera and event.Serial time-encoding amplified imaging(STEAM)can use for imaging non-repetitive and random event at 100 MHz.which have a significance to ultra-fast dynamic event imaging.However,sampling data volumes more greater with the increase of the frame rate which require more storage capacity of storage device.But the price of the storage device is too high to enhance the imaging rate.Therefore,we need propose creativity scheme to compress data volume,and must ensure high fidelity of the image at the same time.In this paper,we proposed ultra-fast imaging system based on differential detection and run-length coding to compress sampling data.We use a balanced-photodetector to replace the traditional single-pixel detector to detect the difference of the two consecutive pulse signals and cancel the same part.At the oscilloscope,the output signal is compressed by the run-length coding algorithm,the same data is retained with one,and groups of the same data is recorded with the multi-bit counter.Since the algorithm is the lossless compression algorithm,all information of the image is preserved and the data volumes is compressed.It worth to noticed that the first detection signal is saved as a reference signal to restore the image.We built a ultra-fast imaging system at imaging rate of 77.86 MHz according to the proposed system scheme,and imaing the standard plate USAF-1951 and human red cells to verify the system reliability.The results of the two experiments show the system compression rate is 3.8 at least and the maximum can reach 11.8.At last,the run-length decompression algorithm can be used to restore the image without information loss.The higher image compression rate of this system can alleviate the data volumes problem of ultrafast imaging,and can promote the development of the STEAM imaging technology further at the imaging rate.