Hybrid optical design for a wide field chromatic confocal scanning interferometer

The approach discussed here overcomes the issue of having to laterally displace the object between consecutive recording positions in chromatic confocal microscopy. It is based on an area sensor in combination with a wavelength tuneable light source and an adaptive optical element. 3D Information can be obtained from the shape of the recorded point images. In case the point is defocused, its spread can be used to calculate the wavelength at which the corresponding object point is in-focus. The setup employed is based on refractive and diffractive optical components. Therefore, a hybrid optical design, combing ray optics and diffraction theory, is used to generate a realistic modelling of the optical system. This detailed description of the system can at a later stage be applied for signal modelling/interpretation. The ray optical system is based on the commercial software Zemax, whereas the description of the diffractive elements is based on Rayleigh Sommerfeld diffraction integral using the angular spectrum method in Matlab. The hybrid optical design and the implemented experimental setup will be shown.