US 3,490,825 — Yasuo Takahashi
| 5 ELEMENTS / 5 GROUPS |
| f = 85mm (PATENT f = 100mm × 0.85) |
| F/4.5 |
| 2ω = 29° (PRODUCTION) |
| ALL-SPHERICAL FUSED-SILICA / FLUORITE |
| 220–1000nm MANUFACTURER CORRECTION RANGE |
Unit extension (inferred from the fixed patent prescription and production helicoid); BFD increases 17.6019 mm from infinity to 0.6 m.
| Element | Type | Glass |
|---|---|---|
| L1 | Biconcave Negative | Fused silica / synthetic quartz (SiO2; patent-identified; Corning HPFS reference dispersion) |
| L2 | Biconvex Positive | Calcium-fluoride fluorite (CaF2; patent-identified; Corning OptiGrade reference dispersion) |
| L3 | Biconvex Positive | Calcium-fluoride fluorite (CaF2; patent-identified; Corning OptiGrade reference dispersion) |
| L4 | Biconcave Negative | Fused silica / synthetic quartz (SiO2; patent-identified; Corning HPFS reference dispersion) |
| L5 | Biconvex Positive | Calcium-fluoride fluorite (CaF2; patent-identified; Corning OptiGrade reference dispersion) |