After laser loading or implosion, the object is in the state of high density and high velocity, and the distribution of internal material and structure is crucial for understanding of the weapon physical process[1-3] and verification of simulation programs. Var the strong penetration of high-energy X-ray, the flash radiography is widely used in implosion process diagnosis[4], to provide key parameters for compression 2D and 3D symmetry.
Due to the spot spatial distribution, scattering, detector resolution and motion blur[5], the image occurred by flash radiography always accompanied by degradation, which causes a decreasing of spatial resolution of total system. The spot distribution, as the intrinsic parameter, determines the system’s minimum resolution[6], which is very important to flash radiography. If the exact information of the spot is known in an experiment, the spot blur can be completely eliminated and deblurred[7]. Therefore, various flash radiography teams are conducting research on X-ray spot measurement methods[8-10]. Unfortunately, due to the jitter of the Marx-based pulse power system, the fluctuation of the excitation power supply and the change of the target state during the beam-target reaction, some random fluctuations in the focal spot distribution occur between shots and pulses, making it almost impossible to obtain the true distribution of an experimental spot. This results in incomplete de-blurring [11]. 
In this project, we carried out weak signal imaging and target information extraction under the high noise interference for the complex noise environment in flash radiography experiments. Using a dedicated calibration object, we can quantitatively assess the impact of a real-time spot monitoring system on the radiography system and quantitatively assess the deblurring effect over an off-axis X-ray spot. Based on the Monte Carlo method, an off-axis spot monitoring system model was developed for quantitative simulation work. The successful development of this method can realize real-time measurement of the flash photography light source and provide important data support for system stability monitoring and image processing.