Laser focal profiler based on forward scattering of a nanoparticle

A laser focal intensity profiling method based on the forward scattering from a nanoparticle is demonstrated for in situ measurements using a laser focusing system with six microscope objective lenses with different numerical apertures ranging from 0.15 to 1.4. The measured profiles showed Airy disc patterns although their rings showed some imperfections due to aberrations and misalignment of the test system. The dipole radiation model revealed that the artefact of this method was much smaller than the influence of the deterioration in the experimental system; a condition where no artefact appears was predicted based on proper selection of measurement angles.