Theoretical analysis of the image with a local intensity minimum during hot image formation in high-power laser systems

The evolution of an image with a local intensity minimum (LIM image) during hot image formation caused by translucent obscuration is theoretically and numerically investigated for the first time to our knowledge. The existence of the LIM image is proved, and the functional relationship describing the intensity of the LIM image is derived by using transfer matrix theory. Furthermore, the influences of the parameters of the obscuration and the nonlinear medium on the intensity of the LIM image are also discussed. The results show that the intensity of the LIM image increases with the increase of the amplitude coefficients of the obscuration, but declines with increasing the thickness of the nonlinear medium within a certain scope. We also found that the distance from the rear surface of the nonlinear medium to the LIM image plane is approximately equal to that from the obscuration plane to the rear surface of the nonlinear medium.