Figure 1 shows a plot for the acrylic-polycarbonate-acrylic air-spaced Cooke triplet lens layout. Similar plots were obtained for the other three plastic lens designs discussed in this article. Figure 2 depicts the relationship between refractive index and wavelength for PMMA, acrylic, polycarbonate and polystyrene plastics and shows that the refractive index value decreases with the increase in wavelength.