https://blog.wongcw.com/2021/02/22/%e6%8f%ad%e7%a7%983nm-2nm%e5%b7%a5%e8%97%9d%e7%9a%84%e6%96%b0%e4%b8%80%e4%bb%a3%e6%99%b6%e9%ab%94%e7%ae%a1%e7%b5%90%e6%a7%8b/