30, 20, and 10 Years Ago in OPN

“As is true in many fields, the advancement of one technology is limited until a second technology is sufficiently developed. This is the case in gradient index. While Otto Schott, R.W. Wood and others made gradient index prior to 1960, the absence of advanced computing power limited the ability to analyze such materials in real optical systems. Ray trace methods were very slow, even for homogeneous spherical surfaces, and the idea that a ray could be traced in a material whose index of refraction varied continuously in the lens was but a dream.”