Near-field optical sensors for particle shape measurements

Two new optical particle shape sensors are introduced. By placing them directly in the near-field of the particle projection (Fresnel region), no lenses or additional optical components are required to obtain particle images. Besides size information, accurate shape information is also obtained. Simulations show that distortion by diffraction is limited and can be reduced even further. Both static and dynamic measurements have been performed, which show that the sensors work as predicted by theory. The sensors have been developed to be applied in a microfluidic cytometer.