Design and comparison of dispersion lens for spectral confocal displacement sensor

Aiming to optimiziong axial chromatic aberration, this paper designed and compared three different dispersion lens configurations for spectral confocal displacement sensor. The designed three-piece dispersion lens exhibited a dispersion range of 6.706 mm, a linear fitting error of 50 nm, and a diffraction limit of 739 μm. The designed four-piece dispersion lens ultilized a dispersion range of 0.992 mm, a linear fitting error of 12 nm, and a diffraction limit of 30 μm. The designed five-piece dispersion lens yielded a dispersion range of 2.174 mm, a linear fitting error of 30 nm, and a diffraction limit of 69 μm. In summary, three-piece lens offered the largest detection range and a smaller linear fitting error. On the other hand, the four-piece lens exhibited the smallest dispersion range, while the fitting error and the diffraction limit were boasted the smallest to that of the three-piece lens. In terms of convenience of assembly and machining, the three-piece lens was superior, with identical glass types that facilitated easier processing and higher cost performance. However, for a balance between resolution and dispersion range, the five-piece dispersion lens should be the better choice.