Self-temperature focus compensation device
Abstract:
A self-temperature focus compensation device adapted to cooperate with a lens group and including at least one Fresnel lens group is provided. Each Fresnel lens group has zero focal power at a specific temperature and is a cemented lens. Each Fresnel lens group includes a first Fresnel lens and a second Fresnel lens. The first Fresnel lens has positive focal power. The second Fresnel lens has negative focal power. A sum of a focal power change of the at least one Fresnel lens group with a temperature change and a focal power change of the lens group with the temperature change is zero.
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