Dispersion lens for chromatic confocal spectral interferometry

The dispersion element that can generate axial dispersion is an essential component of chromatic confocal spectral interferometry (CCSI). In this study, we presented a CCSI system that uses refractive dispersion lens instead of the commonly used diffractive optical element (DOE) to promote imaging quality with a large axial measurement range. The parameters of the dispersion lens are analyzed based on CCSI. Moreover, the design of a dispersion lens with an axial dispersion close to 1 mu m in the wavelength range of 430-710 nm is also presented. The experimental results indicate that even under non-ideal conditions like suboptimal light spectrum, the axial dispersion larger than 150 mu m can still be measured in a 50 nm spectral band. Imaging of the resolution test target demonstrates that the system using dispersion lens achieves a resolution close to 2.76 mu m over a range of 150 mu m, as opposed to an achromatic lens where the resolution decreases rapidly with increasing defocusing distance. The CCSI system was applied to displacement measurement achieving an axial resolution of 0.2 mu m and the measurement errors of less than 0.1 mu m.

Automated summary

In this study, a CCSI system using a refractive dispersion lens instead of a diffractive optical element (DOE) was proposed to improve imaging quality with a large axial measurement range. The parameters of the dispersion lens were analyzed based on CCSI and a dispersion lens with an axial dispersion close to 1 μm was designed. Experimental results showed that even under non-ideal conditions, an axial dispersion larger than 150 μm could still be measured using the system. The system achieved a resolution close to 2.76 μm over a range of 150 μm.