Imaging system using a gradient index lens array with improved depth of focus
US5450157A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 6, 1993 |
| Grant date | Sep 12, 1995 |
| Priority date | — |
| Expiry date | Dec 6, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B3/0087
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An imaging system is disclosed which incorporates a gradient index lens array to transmit focused light onto an image medium with increased Depth of Focus (DOF) and no loss of radiometric efficiency. The lens array is first constructed so that its exit pupil is generally symmetrical. This first step increases the radiometric efficiency of the lens array relative to prior art lens arrays. In a second step, the DOF is increased by reducing a quantity n.sub.o .sqroot.AR which is associated with the lens, n.sub.o being the axial refractive index of the fibers comprising the lens array, .sqroot.A being the gradient index constant of the material comprising the lens array and R being the radius of the individual optical rods, As this quantity is reduced, the DOF increases consistent with a trade off of reduced radiometric efficiency. Since the efficiency was initially increased from some optimum value, the DOF can be increased until the desired radiometric efficiency level is reached.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.