ND FILTER AND PROCESS FOR PRODUCING THE SAME

摘要

PURPOSE: An ND(Neutral Density) filter and a method for manufacturing the same are provided to control light transmittance by partially or continuously changing the thickness of a light attenuation layer. CONSTITUTION: An ND filter includes a resin and a pigment. The resin has the light transmittance of 85% and the thickness between 1 and 380 or 780 nm. The pigment has an absorbing function in a visible ray region. The resin is made of thermoplastic resin. The pigment includes the metal oxide material and the metal nitride material with a first particle diameter of 10 to 80 nm. The pigment is comprised of one selected from the carbon black with the first particle diameter below 50 nm. The ND filter additionally includes an infrared absorber. The pigment is dispersed on the thermoplastic resin.