| 摘要 |
PURPOSE:To obtain excellent soft focus effect while maintaining the resolution of an image forming lens to be mounted properly by providing plural extremely small light refracting parts which have lenticular curved surfaces on a light transmission surface under specific conditions. CONSTITUTION:When an optical element 2 for soft focusing is added to the image forming lens 1, the extremely small refracting parts 3 on the light transmission surface of the element 2 which have the lenticular curved surfaces refract part of luminous flux for forming a spot image P0 on a focal plane F through the added lens 1, thereby forming images at positions P1 and P2/ In this case, the area of a distribution on the plane F about the spot image P0 depends upon the diameter phi of the diffracting parts 3 and the height (h) of the lenticular curved surfaces, and the quantity of distributed light is affected greatly by the mean density of the plural refracting parts 3 (ratio S of the total area of the refracting parts 3 to the sectional area of the surface 2a). for the purpose, phi, (h), and S are so set that 0.05mm<=phi<=0.5mm, 0.5mu<=h<=3mu, and 5%<=S<=35%, obtaining excellent soft focus effect.
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