Quality. Quantity. Cost. In precision manufacturing, the consensus is that you can improve two out of three. You can’t get “more stuff that works better but costs less.”
A hybrid diffractive lens is a refractive optical element with a custom-designed diffraction profile encoded onto one surface. Such a hybrid literally combines the power of refraction and diffraction; as such, a single hybrid lens can replace two or more refractive lenses, especially when utilizing aspheric surfaces. Furthermore, because diffractive surfaces have “negative optical dispersion,” a hybrid lens can make an excellent single-element achromat(*). This technique of combining multiple lenses into single hybrid lenses enables optical designers to reduce the overall mass, volume, and material cost of an optical system.