The principle and keys for measuring prismatic power of helmet viewing window were described.

介绍了头盔面窗棱镜度的测量原理和要点。

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Power is supplied by an internal rechargeable battery (lithium-ion prismatic cell), by an external voltage, or through the USB host.

电力由内部充电电池（圆柱形锂电池）、外接电源或 USB 主机提供。

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