Chromatic confocal spectral interferometry with wavelet analysis

In the present paper, we address a hybrid technique which combines the method of spectral interferometry with chromatic confocal microscopy. On the basis of some proof-of-principle experiments, it is shown that with this new concept, the axial detection range of the sensor is decoupled from the limited depth-of-focus of the employed microscope objective, and a high numerical aperture objective can be employed for detection. The attained interferometric signals consist of high-contrast wavelets, measured in the λ-domain. The position of an investigated object is measured by analyzing the spectral-phase of the attained wavelets. In particular, chirp-effects as well as the significant role of confocal filtering are discussed.