In an optical system, a light blocking film acts as a barrier against stray light, and is generally used as a frame or a whole surface. However, the reflectivity of ordinary ink or photoresist is less than 10%, such a high reflectivity will affect the imaging effect, resulting in flares, edge color anomalies, internal reflection of stray light and other issues. The ultra low anti shading film special design and production, its reflectivity is less than 1.5% (@440-650nm or 0-15), can effectively improve the above problems.