scispace - formally typeset
Search or ask a question
Topic

Depth of focus

About: Depth of focus is a research topic. Over the lifetime, 1839 publications have been published within this topic receiving 26829 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: An imaging method, termed Fourier ptychographic microscopy (FPM), which iteratively stitches together a number of variably illuminated, low-resolution intensity images in Fourier space to produce a wide-field, high-resolution complex sample image, which can also correct for aberrations and digitally extend a microscope's depth-of-focus beyond the physical limitations of its optics.
Abstract: We report an imaging method, termed Fourier ptychographic microscopy (FPM), which iteratively stitches together a number of variably illuminated, low-resolution intensity images in Fourier space to produce a wide-field, high-resolution complex sample image. By adopting a wavefront correction strategy, the FPM method can also correct for aberrations and digitally extend a microscope’s depth of focus beyond the physical limitations of its optics. As a demonstration, we built a microscope prototype with a resolution of 0.78 µm, a field of view of ∼120 mm^2 and a resolution-invariant depth of focus of 0.3 mm (characterized at 632 nm). Gigapixel colour images of histology slides verify successful FPM operation. The reported imaging procedure transforms the general challenge of high-throughput, high-resolution microscopy from one that is coupled to the physical limitations of the system’s optics to one that is solvable through computation.

1,363 citations

Journal Article
TL;DR: The phase-shifting mask as mentioned in this paper consists of a normal transmission mask that has been coated with a transparent layer patterned to ensure that the optical phases of nearest apertures are opposite.
Abstract: The phase-shifting mask consists of a normal transmission mask that has been coated with a transparent layer patterned to ensure that the optical phases of nearest apertures are opposite. Destructive interference between waves from adjacent apertures cancels some diffraction effects and increases the spatial resolution with which such patterns can be projected. A simple theory predicts a near doubling of resolution for illumination with partial incoherence σ < 0.3, and substantial improvements in resolution for σ < 0.7. Initial results obtained with a phase-shifting mask patterned with typical device structures by electron-beam lithography and exposed using a Mann 4800 10× tool reveals a 40-percent increase in usuable resolution with some structures printed at a resolution of 1000 lines/mm. Phase-shifting mask structures can be used to facilitate proximity printing with larger gaps between mask and wafer. Theory indicates that the increase in resolution is accompanied by a minimal decrease in depth of focus. Thus the phase-shifting mask may be the most desirable device for enhancing optical lithography resolution in the VLSI/VHSIC era.

705 citations

Book ChapterDOI
TL;DR: This chapter has discussed the nature of image formation in three dimensions and dealt with several means to remove contaminating out-of-focus information and developed a method for extremely rapidly and accurately producing an in-focus, high-resolution "synthetic projection" image from a thick specimen.
Abstract: The combination of the specificity provided by fluorescence microscopy and the ability to quantitatively analyze specimens in three dimensions allows the fundamental organization of cells to be probed as never before Key features in this emergent technology have been the development of a wide variety of fluorescent dyes or fluorescently labeled probes to provide the requisite specificity High-quality, cooled charge-coupled devices have recently become available Functioning as nearly ideal imagers or "electronic film," they are more sensitive than photomultipliers and provide extraordinarily accurate direct digital readout from the microscope Not only is this precision crucial for accurate quantitative imaging such as that required for the ratioing necessary to determine intracellular ion concentrations, but it also opens the way for sophisticated image processing It is important to realize that image processing isn't simply a means to improve image aesthetics, but can directly provide new, biologically important information The impact of modern video microscopy techniques (Allen, 1985; Inoue, 1986) attests to the fact that many biologically relevant phenomena take place at the limits of conventional microscopy Image processing can be used to substantially enhance the resolution and contrast obtainable in two dimensions, enabling the invisible to be seen and quantitated Cells are intrinsically three-dimensional This can simply be a nuisance because of limited depth of focus of the microscope or it could be a fundamental aspect of the problem being studied In either case, image processing techniques can be used to rapidly provide the desired representation of the data In this chapter we have discussed the nature of image formation in three dimensions and dealt with several means to remove contaminating out-of-focus information The most straightforward of these methods uses only information from adjacent focal planes to correct the central one This approach can be readily applied to virtually any problem and with most commonly available image processing hardware to provide a substantially deblurred image in almost real time In addition to covering more sophisticated algorithms where the utmost in three-dimensional imaging is required, we have developed a method for extremely rapidly and accurately producing an in-focus, high-resolution "synthetic projection" image from a thick specimen This is equivalent to that produced by a microscope having the impossible combination of a high-NA objective lens and an infinite depth of focus A variation on this method allows efficient calculation of stereo pairs(ABSTRACT TRUNCATED AT 400 WORDS)

702 citations

Journal ArticleDOI
TL;DR: The phase-shifting mask as mentioned in this paper consists of a normal transmission mask that has been coated with a transparent layer patterned to ensure that the optical phases of nearest apertures are opposite.
Abstract: The phase-shifting mask consists of a normal transmission mask that has been coated with a transparent layer patterned to ensure that the optical phases of nearest apertures are opposite. Destructive interference between waves from adjacent apertures cancels some diffraction effects and increases the spatial resolution with which such patterns can be projected. A simple theory predicts a near doubling of resolution for illumination with partial incoherence σ < 0.3, and substantial improvements in resolution for σ < 0.7. Initial results obtained with a phase-shifting mask patterned with typical device structures by electron-beam lithography and exposed using a Mann 4800 10X tool reveals a 40-percent increase in usuable resolution with some structures printed at a resolution of 1000 lines/mm. Phase-shifting mask structures can be used to facilitate proximity printing with larger gaps between mask and wafer. Theory indicates that the increase in resolution is accompanied by a minimal decrease in depth of focus. Thus the phase-shifting mask may be the most desirable device for enhancing optical lithography resolution in the VLSI/VHSIC era.

667 citations

Journal ArticleDOI
TL;DR: It is demonstrated that digital holographic microscopy can resolve the locations of several thousand particles and can measure their motions and trajectories using cinematographic holography, and a sample trajectory and detailed morphological information of a free-swimming copepod nauplius are presented.
Abstract: Better understanding of particle-particle and particle-fluid interactions requires accurate 3D measurements of particle distributions and motions. We introduce the application of in-line digital holographic microscopy as a viable tool for measuring distributions of dense micrometer (3.2 microm) and submicrometer (0.75 microm) particles in a liquid solution with large depths of 1-10 mm. By recording a magnified hologram, we obtain a depth of field of approximately 1000 times the object diameter and a reduced depth of focus of approximately 10 particle diameters, both representing substantial improvements compared to a conventional microscope and in-line holography. Quantitative information on depth of field, depth of focus, and axial resolution is provided. We demonstrate that digital holographic microscopy can resolve the locations of several thousand particles and can measure their motions and trajectories using cinematographic holography. A sample trajectory and detailed morphological information of a free-swimming copepod nauplius are presented.

440 citations


Network Information
Related Topics (5)
Lens (optics)
156.4K papers, 1.2M citations
75% related
Interferometry
58K papers, 824.8K citations
75% related
Laser
353.1K papers, 4.3M citations
74% related
Wavelength
53.9K papers, 806.8K citations
74% related
Optical fiber
167K papers, 1.8M citations
73% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20222
202141
202053
201953
201850
201754