Scanner lens and method for producing the same

A method for producing a scanner lens of plastic used in an optical scanning system, the method comprising the steps of:

• obtaining lateral magnification of the optical scanning system;
• obtaining the maximum value of thickness in the optical axis direction of the scanner lens;
• obtaining allowance b on one side and beam diameter a in the vertical scanning direction in the scanner lens;
• obtaining width h in the vertical scanning direction of the scanner lens by the following expression
• h=a+2b;
• wherein the allowance b is a product of the maximum value of thickness in the optical axis direction of the scanner lens and a coefficient, and the coefficient is determined according to the lateral magnification of the optical scanning system in such a way that the maximum value of movement of the focal point of the scanner lens due to moisture absorption is made smaller than or equal to a predetermined value.