Abstract
This paper gives a review on the design and use of both amplitude filters and phase filters to achieve a large focal depth in incoherent imaging systems. Traditional optical system design enhances the resolution of incoherent imaging systems by optical-only manipulations or some type of post-processing of an image that has been already recorded. A brief introduction to recent techniques to increase the depth of field by use of hybrid optical/digital imaging system is reported and its performance is compared with a conventional optical system. This technique, commonly named wavefront coding, employs an aspherical pupil plane element to encode the incident wavefront in such a way that the image recorded by the detector can be accurately restored over a large range of defocus. As reported in earlier work, this approach alleviates the effects of defocus and its related aberrations whilst maintaining diffraction-limited resolution. We explore the control of third order aberrations (spherical aberration, coma, astigmatism, and Petzval field curvature) through wavefront coding. This method offers the potential to implement diffraction-limited imaging systems using simple and low-cost lenses. Although these performances are associated with reductions in signal-to-noise ratio of the displayed image, the jointly optimised optical/digital hybrid imaging system can meet some specific requirements that are impossible to achieve with a traditional approach.
Original language | English |
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Pages (from-to) | 238-248 |
Number of pages | 11 |
Journal | Proceedings of SPIE - the International Society for Optical Engineering |
Volume | 5249 |
DOIs | |
Publication status | Published - 2004 |
Event | Optical Design and Engineering - St. Etienne, France Duration: 30 Sept 2003 → 3 Oct 2003 |
Keywords
- Apodizer
- Defocus
- Depth of field
- Pupil plane
- Spherical and third order aberration
- Wavefront coding