Measurement of Axial Position of a Microsphere Using Chromatic Confocal System for Probe System Based on the Laser Trapping with the Standing Wave Scale

We have proposed surface scanning measurement based on the laser trapping based probe with the standing wave scale (SWS). A scale resolution of SWS is subject to the wavelength of laser and of the hundred nm order, so the interpolation of the SWS is required. The microsphere used for probe, which is the sensor to read the SWS, is located where the forces by the laser trapping and by the standing wave field are balanced, so that the microsphere position depends on the displacement of the sample. For the interpolation of the SWS, axial position of the microsphere must be measured with high accuracy and high resolution. In this report, chromatic confocal system is proposed. As a result the measuring range and the resolution are achieved 5 μm and 10 nm, respectively.