| for reflecting light toward the aperture | 4 | purpose |
| surface → have → curvature | 20 |
| surface → have → irregular curvature | 8 |
| surface → have → the curvature | 3 |
| negative | neutral | positive |
| 0.193 | 0.720 | 0.087 |
| Raw frequency | 31 |
| Normalized frequency | 0.346 |
| Modifier score | 0.900 |
| Perplexity | 48.462 |