The submarine movement underwater can produce special internal wave which will rise and arrive at the water surface and make up a kind of the special weak texture. The texture makes it possible to detect through infrared remote sensing device. But the texture signal usually has very low contrast and is always mixed with intensive clutter in the sea surface background. Therefore, it is very difficult to extract these special textures from all the captured information. After comparing the advantage and disadvantage in the state of art for the texture extraction, optical filtering based on incoherent light was used for enhancing Signal-Clutter-Ratio(SCR) of the weak texture on the water surface. That will make the extraction much easier. Based on the optical principle of interference filtering and SCR evaluation method for the ability of the device to extract the weak texture signal on the water surface, optical filtering method for signals with different frequency was analyzed and evaluated by SCR. The optical transfer function of interference light was optimized according to the target frequency of the weak-texture signals. The simulation and experiment were implemented for verifying the feasibility. The optimized double-aperture optical system has better ability to extract the weak texture, which has showed that 7% SCR enhancement can be derived for the weak texture model and signal from this system. Combined with the digital contrast method, the ability for extracting the weak texture from the sea surface can be further improved.