Modern aspheric design, computers, materials for molds and lenses, and advanced production and measuring equipment make possible accurate plastic lens elements that can meet requirements that used to need several elements. Reviewed are miniature TV camera lenses, laser diode collimator lenses and magnification with some detail regarding design, accuracy, and the low costs that can be achieved.
Ian K. Pasco,
"Single-element plastics aspherics: the economical approach to precision optics", Proc. SPIE 1780, Lens and Optical Systems Design, 178016 (15 April 1993); doi: 10.1117/12.142837; https://doi.org/10.1117/12.142837