| 359 / | HD | OPTICS: SYSTEMS (INCLUDING COMMUNICATION) AND ELEMENTS |
| 642 | DF | LENS {32} |
| 726 | DF | .~ With reflecting element {3} |
| 727 | DF | .~.~ Including concave or convex reflecting surface {2} |
| 730 | DF | .~.~.~ Reflectors in series {1} |
| 731 | ![]() | .~.~.~.~ With concave and convex reflectors in series |