| 摘要 |
A single f-&thetas; lens used for a micro-electro mechanical system (MEMS) laser scanning unit is in a meniscus shape formed by the lens in which a concave surface faces towards the side of a MEMS reflecting mirror. The single f-&thetas; lens has a first optical surface and a second optical surface, at least one optical surface is aspherical surface in both main scanning direction and sub scanning direction, and satisfies specifical optical conditions. The single f-&thetas; lens converts the nonlinear relationship between scanned angle and the time into the linear relationship between the imaged spot distances and the time. Meanwhile, the single f-&thetas; lens focuses the scan light to the target in the main scanning and sub scanning directions, such that the purpose of the scanning linearity effect and the high resolution scanning can be achieved.
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