ABSTRACT
Although the binary-optic method of making microlenses may be the source of the current excitement in the micro-optics field, as we will see in Chapter 4, it was the gradient index method pioneered by Nippon Sheet Glass that paved the way, and in many ways still dominates the field. We will see in succeeding sections of this chapter how the ingenious use of an ion-exchange process in glass provided the first practical way to make microlenses. This method of making an imaging device is generically called GRIN, for gradient index, so you will see people use the description GRIN lens to mean any lens formed through refractive index profile.
