| 摘要 |
PURPOSE:To effectively reduce an interference fringe by obtaining a laser beam through the use of a light beam generating means to generate the light beams of plural number of wavelengths. CONSTITUTION:Because an optical path difference delta(lambda1) between the laser beam L1(lambda1) and L2(lambda1) varies according to a scanning position, the sum of both light quantities varies by an interference between the L1(lambda1) and the L2(lambda1), and the interference fringe appears. Now, as for the laser beam L2(lambda2) of the different wavelength lambda2, an entirely same phenomenon appears. When the optical path difference delta(lambda1) of an incident light L0(lambda1) is assumed to be the integer-times of the wavelength lambda1, if the optical path differnce delta(lambda2)(=delta(lambda1)) of the L0(lambda2) is different from is integer-times of the wavelength lambda2 by a half wavelength, namely, if the phase difference alpha between both is pi, the interference fringes of both so as to cancel each other. Accordingly, as far as this condition is maintained, the interference fringe is canceled by each other, and a good image reading can be obtained. |
