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. 2024 Aug 28;15:1398894. doi: 10.3389/fneur.2024.1398894

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Copyright © 2024 Henderson.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

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(A) Image of light meter display when a 10 W laser at 810 nm is placed 2 mm from a light meter. (B) The meter registers 9.79 W penetrating this distance of air. (C) A portion of hair approximately 2 mm in thickness is placed in between the NIR emitter and the light meter. (D) Image of meter display – only 0.236 W of NIR energy from the 10 W emitter can penetrate the hair to register on the meter [Adapted from Henderson and Morries (7). Used with permission].