| 摘要 |
The disclosure is directed to hologram elements, illuminators, and projectors. In one example, a hologram element comprises a relief structure configured to diffract incident light to form a first illumination pattern and a second illumination pattern on an illuminated surface. The second illumination pattern may form a specific mark for uniquely identifying the hologram element. In certain embodiments, the second illumination pattern is formed outside an illumination area. In other embodiments, the second illumination area is formed inside the illumination area.
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