Editing Radiation pressure (section)

=== Optical tweezers ===
{{Main|Optical tweezers}}
[[Laser]]s can be used as a source of monochromatic light with wavelength <math>\lambda</math>. With a set of lenses, one can focus the laser beam to a point that is <math>\lambda</math> in diameter (or <math>r = \lambda/2</math>).

The radiation pressure of a ''P'' = 30&nbsp;mW laser with ''λ'' = 1064&nbsp;nm can therefore be computed as follows.

Area:
<math display="block">A = \pi\left(\frac{\lambda}{2}\right)^2 \approx 10^{-12} \text{ m}^2,</math>

force:
<math display="block">F = \frac{P}{c} = \frac{30 \text{ mW}} {299792458 \text{ m/s}} \approx 10^{-10} \text{ N},</math>

pressure:
<math display="block">p = \frac{F}{A} \approx \frac{10^{-10} \text{ N}} {10^{-12} \text{ m}^2} = 100 \text{ Pa}.</math>

This is used to trap or levitate particles in [[optical tweezers]].