| Number | Name | Date | Kind |
|---|---|---|---|
| 2881654 | Toffolo | Apr 1959 | |
| 2882784 | Toffolo | Apr 1959 | |
| 4277148 | Clegg | Jul 1981 | |
| 4325612 | Clegg | Apr 1982 | |
| 4333713 | Clegg | Jun 1982 | |
| 4556294 | Clegg | Dec 1985 |
| Entry |
|---|
| Yaffee et al; "Adjusting the Collection Angle of a Conical Lens by Immersion in a Liquid"; Applied Optics; vol. 9, No. 10, Oct. 1970; p. 2389. |