micron

For example, if you say that something is "a few microns across", explain that a micron is one-millionth of a metre, and "about one hundredth the width of a human hair".

例如，如果您说某事物只有几微米，那么就要解释一微米是百万分之一米，大约是人头发宽度的百分之一。

One micron is a thousandth of a millimeter: a pinhead is about a millimeter across.

一微米等于千分之一毫米。 针头直径大约一毫米。