Extended depth of field using a logarithmic asphere

George, Nicholas; Chi, Wanli

doi:10.1088/1464-4258/5/5/358

Cited by 71 publications

(32 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Note that at the near object distance l(λ 1 ) the F# and working F# differ by approximately 1.5% and this discrepancy is to some extent compensated by the approximation made in Eq. (12). The exact value for the focal length verified in Zemax is f = 4.825 mm with corresponding f-number for an object at infinity is F# = 2.68 and working f-number = 2.72.…”

Section: Optical System Examplesmentioning

confidence: 97%

“…Logarithmic aspheres together with post-processing employ a non-paraxial form of diffraction theory to create a desired PSF, that can be used to compute and fabricate a blurring phase filter or aspheric lens, which is then combined with a commercial lens [12]. Changing the geometrical focus in real time using a liquid lens has been proven experimentally.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Extending the depth of field with chromatic aberration for dual-wavelength iris imaging

Fitzgerald¹,

Dainty²,

Goncharov³

2017

Opt. Express

View full text Add to dashboard Cite

Abstract:We propose a method of extending the depth of field to twice that achievable by conventional lenses for the purpose of a low cost iris recognition front-facing camera in mobile phones. By introducing intrinsic primary chromatic aberration in the lens, the depth of field is doubled by means of dual wavelength illumination. The lens parameters (radius of curvature, optical power) can be found analytically by using paraxial raytracing. The effective range of distances covered increases with dispersion of the glass chosen and with larger distance for the near object point.

show abstract

Section: Optical System Examplesmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Extending the depth of field with chromatic aberration for dual-wavelength iris imaging

Fitzgerald¹,

Dainty²,

Goncharov³

2017

Opt. Express

View full text Add to dashboard Cite

show abstract

“…George and Chi [106] propose the use of a logarithmic asphere and image processing to increase the depth of field. Castro and Ojeda-Castañeda [107] present a family of asymmetric phase masks that extends the depth of field of an optical system.…”

Section: B Wavefront Codingmentioning

confidence: 99%

Computational Cameras: Convergence of Optics and Processing

Zhou

Nayar

2011

IEEE Trans. on Image Process.

105

View full text Add to dashboard Cite

Abstract-A computational camera uses a combination of optics and processing to produce images that cannot be captured with traditional cameras. In the last decade, computational imaging has emerged as a vibrant field of research. A wide variety of computational cameras has been demonstrated to encode more useful visual information in the captured images, as compared with conventional cameras. In this paper, we survey computational cameras from two perspectives. First, we present a taxonomy of computational camera designs according to the coding approaches, including object side coding, pupil plane coding, sensor side coding, illumination coding, camera arrays and clusters, and unconventional imaging systems. Second, we use the abstract notion of light field representation as a general tool to describe computational camera designs, where each camera can be formulated as a projection of a high-dimensional light field to a 2-D image sensor. We show how individual optical devices transform light fields and use these transforms to illustrate how different computational camera designs (collections of optical devices) capture and encode useful visual information.

show abstract

“…Either approach is then combined with a commercial lens. 7 An electrically tuneable liquid lens has been shown to be capable of producing three different lens powers and increasing the spatial depth perception to twice that of a conventional endoscope without image post processing. 8 An EDOF effect can be produced by introducing a variable focal objective.…”

Section: Introductionmentioning

confidence: 99%

Extending the Depth of Field in a Fixed Focus Lens Using Axial Colour

Fitzgerald¹,

Goncharov²,

Dainty³

2017

Optical Design and Fabrication 2017 (Freeform, IODC, OFT)

View full text Add to dashboard Cite

We propose a method of extending the depth of field (EDOF) of conventional lenses for a low cost iris recognition front-facing smartphone camera. Longitudinal chromatic aberration (LCA) can be induced in the lens by means of dual wavelength illumination. The EDOF region is then constructed from the sum of the adjacent depths of field from each wavelength illumination. The lens parameters can be found analytically with paraxial raytracing. The extended depth of field is dependant on the glass chosen and position of the near object point.

show abstract

Extended depth of field using a logarithmic asphere

Cited by 71 publications

References 3 publications

Extending the depth of field with chromatic aberration for dual-wavelength iris imaging

Extending the depth of field with chromatic aberration for dual-wavelength iris imaging

Computational Cameras: Convergence of Optics and Processing

Extending the Depth of Field in a Fixed Focus Lens Using Axial Colour

Contact Info

Product

Resources

About