Abstract: A crt optical filter device includes a transparent plastic sheet and a transparent glass panel, each of which is provided with a transparent conductive circuit layer and a pair of conductors. The outer surface of the glass panel is disposed adjacent to the inner surface of the transparent plastic sheet, while the inner surface thereof is to be disposed adjacent to a screen of a computer monitor. A plurality of spacers, which are made of an insulative material, normally space apart the conductive circuit layers of the transparent plastic sheet and the glass panel. An interface card is connected electrically to the conductors and is to be connected electrically to a computer. The interface card receives analog X and Y signals that correspond to a selected part of the transparent plastic sheet from the conductors when the conductive circuit layers are brought into electrical contact due to application of pressure on the selected part of the transparent plastic sheet.