| 356 / | HD | OPTICS: MEASURING AND TESTING |
| 928 | DD | INVESTIGATING OR ANALYZING MATERIALS BY THE USE OF OPTICAL MEANS, I.E., USING INFRA-RED, VISIBLE, OR ULTRA-VIOLET LIGHT (GO1N 21/00) {5} |
| 948 | DD | .~ Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light (GO1N 21/62) {1} |
| 949 | DD | .~.~ Optically excited (GO1N 21/63) {3} |
| 950 | | .~.~.~ Using photolysis and investigating photolyzed fragments (GO1N 21/63C) |