trapezoidal shape that is symmetric laterally a line that is perpendicular to prarallel two sides of the trapezoid has only to agree with an optical axis of the optical functional section further as another improvement it is also possible to provide a three dimensional distinguishing mark on supporting shaft section 1 through molding as shown in fig1 in this case the first resin inflow path 31 runner of the metal mold is processed in advance so that the distinguishing mark may be formed thereon now as shown in fig1 c and 18 d index portion 42 a may be provided on connecting section 42 in this case gate 2 of the metal mold m has only to be machined in advance so that the index portion 42 a may be formed on connecting section 42 in the example shown in fig1 there are formed bar code and letters a direction a size and a shape of these distinguishing mark can be established independently incidentally although the bar code and the letters are formed on the supporting section 41 in fig1 the bar code and the letters may be formed on the connecting section 42 further the distinguishing mark like this can also include a metal mold number and a cavity number in addition to symbols indicating a product name and a lot if these distinguishing marks are included it is possible to use them when checking and extracting defective products in the succeeding process further as shown in fig1 c and 18 d index portion 42 a that is based on a distance from the center of an optical axis of the optical functional section 43 may be provided on connecting section 42 fig1 d shows that the index portion 42 a is formed by cutting into the connecting section.