Study on impact of spatial filter on a hot image through medium with gain

The evolution of hot image formation through medium with gain in consideration of the effect of spatial filter is theoretically and numerically investigated. Based on the linear diffraction theory and small-scale self-focusing theory of Bespalov and Talanov, intensity distribution of hot image in conjugate plane is derived analytically. Then, the peak intensity of hot image for different medium gain and different pinhole sizes are discussed in detail, the results show theoretical analysis is mostly approximate to the numerical simulations, furthermore, it is found that suppressing effect on peak intensity ratio with small gain coefficient is larger than that with bigger ones for determined pinhole size.