ABSTRACT
Image diagnosis is an important technique in transient process research of high-energy physics. High dynamic range scenes require high linear dynamic range imaging systems. Scientific CMOS (sCMOS) image sensors have widely been used in high-energy physics, nuclear medical imaging, and astronomical observation because of their advantages in the high linear dynamic range. In this paper, we study the gain ratio variation and background value variation of commercial sCMOS image sensors. A self-adaptive fusion method is proposed to realize the fusion of high linear dynamic range images. The proposed method only uses the high gain image and the low gain image of the sCMOS image sensor to evaluate the gain ratio and the background compensation. The measured results show that the error rates of the evaluated gain ratio and background compensation are less than 2% and 6%. Test results show that the self-adaptive fusion method realizes well the fusion effects, which efficiently avoids the influence of gain ratio variation and background value variation.
ABSTRACT
Sequential equivalent time sampling (ETS) has been extensively used in data acquisition instruments (e.g., sampling oscilloscopes and time domain reflectometers). A novel step delay method is proposed based on the frequency difference to obtain a higher sampling rate in sequential ETS. It is different from the classic step delay methods and is capable of increasing the sampling rate. The sampling clock and the repetitive signal are taken as examples in this study. The time-frequency conversion relationship indicates that a fine step delay will be generated in the time domain if there is a frequency difference between the two in the frequency domain. The core of the proposed method is the selection of the appropriate frequency difference (step delay) according to the desired equivalent sampling rate. Two experiments were performed to verify the proposed method. The feasibility of the proposed method is verified using a digital storage oscilloscope. Four cases are examined in the experiment, and the final equivalent sampling rate is obtained as 5 PS/s for the equivalent sampling of a 4.999 995 GHz (or higher) signal. A data acquisition system with a 10 MS/s real-time sampling rate is designed to verify the feasibility of the proposed method, obtaining a theoretical equivalent sampling rate of 585 GS/s. The theoretical equivalent sampling rate and the examined equivalent sampling rate are consistent. The equivalent sampling waveform and real-time sampling waveform of a 1 GHz signal are compared, and the comparison result suggests that the proposed method can acquire more waveform information. The proposed method obtains a high equivalent sampling rate for repetitive signals, and techniques (e.g., oversampling) are given to obtain higher vertical resolution. The proposed method, combined with a sample-and-hold amplifier, can also achieve a higher analog bandwidth.
ABSTRACT
An all-optical framing camera has been developed which measures the spatial profile of photons flux by utilizing a laser beam to probe the refractive index change in an indium phosphide semiconductor. This framing camera acquires two frames with the time resolution of about 1.5 ns and the inter frame separation time of about 13 ns by angularly multiplexing the probe beam on to the semiconductor. The spatial resolution of this camera has been estimated to be about 140 µm and the spectral response of this camera has also been theoretically investigated in 5 eV-100 KeV range. This camera has been applied in investigating the imploding dynamics of the molybdenum planar wire array Z-pinch on the 1-MA "QiangGuang-1" facility. This framing camera can provide an alternative scheme for high energy density physics experiments.
