| 摘要 |
An optical integrator having characteristics to reduce effects of manufacturing errors of many minute refraction surfaces integrally formed by, for example, etching on an illumination intensity distribution. An optical integrator ( 8 ) comprising an integrally formed plurality of first minute refraction surfaces ( 80 a) and an integrally formed plurality of second minute refraction surfaces ( 80 b). A parameter beta satisfies conditions, |beta|<0.2 (where beta=(gamma-1)<SUP>3</SUP>.NA<SUP>2</SUP>/Deltan<SUP>2</SUP>), where a refracting power ratio phia/phib between phia, a refracting power of the first minute refraction surfaces and phib, a refracting power of the second minute refraction surfaces is gamma, numerical aperture on an emission side of the optical integrator is NA, and a difference between a refraction index of a medium on a light entrance side of the second minute refraction surfaces and a refraction index of a medium on a light emission side of the second minute refraction surfaces is Deltan.
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