Fig. 1. Axial and side views of binary optical lens

Fig. 2. Schematic of axial dispersion of binary optical lens

Fig. 3. Schematic of spectral confocal micro-spacing measurement of binary optical lens

Fig. 4. Diffraction images when image screen is at different locations from binary optical lens. (a) 20 mm; (b) 40 mm; (c) 50 mm; (d) 60 mm; (e) 80 mm

Fig. 5. Intensity distributions when image screen is at different locations from binary optical lens. (a) 20 mm; (b) 40 mm; (c) 50 mm; (d) 60 mm; (e) 80 mm

Fig. 6. Diffraction patterns under different incident light wavelengths when distances between light screen and binary optical lens are different. From top to bottom, distances between light screen and binary optical lens are 42.969, 46.610, 50.000, and 55.000 mm, respectively. From left to right, incident light wavelengths are 500, 550, 590, and 640 nm, respectively

Fig. 7. Original spectrum of spectrometer

Fig. 8. Spectra received by spectrometer at different locations

Fig. 9. Focal position of incident light with different wavelengths corresponds to axial coordinate of three-dimensional translation stage

Fig. 10. Measured optical disc

Fig. 11. Spectra of two adjacent thin films of optical disc