A successful career contributed to keeping OpticalRayTracer—an optical design software program—free. Before the Macintosh, developer Paul Lutus wrote a best-selling, word-processing program called Apple Writer. “As a result of this success,” says Lutus, “I lost any financial incentive to sell programs, but I still like programming.” He adds, “So over the years I've written many programs, all of which are free and available for download on my website—www.arachnoid.com—and from the Google Play store.”
Instead of money, Lutus used to ask people to make a “philosophical payment” for his software, including OpticalRayTracer. On his CareWare page, for example, he describes a possible payment as: “I ask that you stop whining about how hard your life is, at least for a while.” That seems like a fair-enough trade to me, but now he asks for nothing at all. Lutus says, “Over time, I’ve decided that people can decide for themselves how to ‘pay’ for a free program, perhaps by paying it forward in a way they decide on their own.”
For people interested in learning about designing optics, Lutus’s OpticalRayTracer comes for free and keeps on giving. As Lutus explains, “OpticalRayTracer is released under the GNU General Public License, which means the source code is freely available and users have the right to create their own program versions under the same licensing terms.” So you can get the program for free, modify it as you like, and learn about and design all kinds of optics along the way. That leaves nothing to whine about—just enjoy the fruits of free software from Lutus. It doesn’t get much better than that.