| 摘要 |
<p>At least one surface of a lens has a double curve with a surface discontinuity ar the optical axis. A number of combinations of surfaces are possible such as the bicurve-convexo lens of Figure 1a. Bicurve lenses may be used to provide a greater light capture and depth of field than conventional lenses with reduced sperical aberration. Because an annular focus is produced, bicurve lenses may be used with a diaphragm which exands radially from the optical axis to stop the lens, this arrangement being more compact than conventional aperture adjusting devices.</p> |
