| 摘要 |
This invention is directed to a restricted off-axis field optical system having a broad spectral range, which first and second nearly concentric optical subsystems, said subsystems being constructed and arranged with respect to each other so that variation in performance of one subsystem with wavelength substantially balances that of the other. That is, the subsystems are constructed and arranged with respect to each other so that the sum of the refractive power is nearly zero and the sum of the reflective power is also nearly zero. |
