| 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} |
| 931 | DD | .~ Systems in which incident light is modified in accordance with the properties of material investigated (GO1N 21/17) {8} |
| 933 | | .~.~ With calorimetric detection, e.g., with thermal lens detection (GO1N 21/17C) |