jep@oink.UUCP (James E. Prior) (05/23/89)
I've noticed that when I look closely at reasonably clean bare steel in good sunlight that it appears to have a very fine grain of colors. What is this due to? Is it an artifact of vision or does the steel actually have all those speckled colors? -- Jim Prior jep@oink osu-cis!n8emr!oink!jep N8KSM
jwl@ernie.Berkeley.EDU (James Wilbur Lewis) (05/24/89)
In article <31@oink.UUCP> jep@oink.UUCP (James E. Prior) writes: >I've noticed that when I look closely at reasonably clean bare steel in good >sunlight that it appears to have a very fine grain of colors. > >What is this due to? Probably a diffraction-grating type effect due to scratches, roughness, or possibly crystalline structure at the surface. I've heard that a similar phenomenon is responsible for iridescent blue coloring of certain kinds of birds...there's not actually a pigment of that color, but the fine structure of the feathers makes the reflected light look bluish. -- Jim Lewis U.C. Berkeley
eugene@eos.UUCP (Eugene Miya) (05/24/89)
In article <29298@ucbvax.BERKELEY.EDU> jwl@ernie.Berkeley.EDU.UUCP (James Wilbur Lewis) writes: >In article <31@oink.UUCP> jep@oink.UUCP (James E. Prior) writes: >>I've noticed that when I look closely at reasonably clean bare steel in good >>sunlight that it appears to have a very fine grain of colors. >> >>What is this due to? > >Probably a diffraction-grating type effect due to scratches, roughness, or >possibly crystalline structure at the surface. Funny you should mention this. I was sitting with my officemate, George Michael, he says Hi Kelly, and we were talking about stuff and he brought up the subject of polish. He said there were people at Livenomore who were researching the issue of polish for big mirrors, but that polish really isn't well understood, still open interesting physical science questions. Polish consists of minute "scratches" which have a set of interesting properties. You can probably to them and get TRs on the topic. Polish is more than irradesence. Also, since somebody asked, the date on the Science article by Greenberg on Light reflection models for graphics is 14 April 1989, page 166. It will provide simple models for this type of stuff. Another gross generalization from --eugene miya, NASA Ames Research Center, eugene@aurora.arc.nasa.gov resident cynic at the Rock of Ages Home for Retired Hackers: "You trust the `reply' command with all those different mailers out there?" "If my mail does not reach you, please accept my apology." {ncar,decwrl,hplabs,uunet}!ames!eugene Live free or die.