Adjacent sequence iteration method for designing a diffractive element with function of long focal depth
01 Oct 2004-Optical Engineering (International Society for Optics and Photonics)-Vol. 43, Iss: 10, pp 2348-2352
TL;DR: An adjacent sequence iteration method for designing a dif- fractive element with function of controlling wavefront propagation is pre- sented, and a binary optical element for focusing a diode laser beam in a long focal depth is designed with this method, fabricated by means of photolithography and ion-etching techniques as discussed by the authors.
Abstract: An adjacent sequence iteration method for designing a dif- fractive element with function of controlling wavefront propagation is pre- sented, and a binary optical element for focusing a diode laser beam in a long focal depth is designed with this method, fabricated by means of photolithography and ion-etching techniques. The simulation calculated with the designed element indicates that the design is successful, and the experiment results of long focal depth by testing the produced ele- ment are consistent with the design requirements. © 2004 Society of Photo-
Citations
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TL;DR: In this article, a technique of varying each zone area of a phase spiral zone plate was proposed to obtain optics capable of generating ultra-long focus-depth optical vortex from a plane wave.
13 citations
TL;DR: In this article, a linear varied-area zone plate was proposed, in which arbitrary long focal depth can be achieved by properly adjusting the corresponding parameters, while the lateral focal spot and side lobes can be kept very small.
Abstract: We report a linear varied-area zone plate, in which arbitrary long focal depth can be achieved by properly adjusting the corresponding parameters. Meanwhile, the lateral focal spot and side lobes can be kept very small. Numeral simulations are carried out to verify the performance of our zone plate through Fresnel–Kirchhoff diffraction theory, and the results are in good accord with the experimental verifications. The influences of our zone plate’s parameters to the intensity distribution in focal region are discussed in detail. Comparisons are made with the behaviour of a linear varied-line-space grating, and we find that the behaviour of our novel zone plate along optical axis is just like a reverse transformation of the focusing behaviour of a linear varied-line-space grating.
10 citations
TL;DR: In this paper, a nonlinear phase fitting method is proposed to duplicate the performance of logarithmic axicon, which can obtain a beam with long-focal-depth, small focal spot and side lobe.
7 citations
TL;DR: In this article , it was shown that an accelerating superluminal laser focus can be always generated by this extension, in which the degree of acceleration increases with the increase of numerical aperture, and the velocity of laser focus increases approximately linearly from c to 1.6 c for NA = 0.707.
Abstract: The long-focal-depth mirror is a novel reflective element proposed in recent years. Due to the advantages of negligible dependence on wavelength and high damage threshold, it is suitable to focus ultra-short laser pulses with broadband spectra and high intensity with a focal depth of centimeter scale. To the best of our knowledge, the focusing properties of this mirror has been only studied under low numerical aperture (NA). In this paper, we extend it to the case of high NA and it is proved that an accelerating superluminal laser focus can be always generated by this extension, in which the degree of acceleration increases with the increase of NA. And the velocity of laser focus increases approximately linearly from c to 1.6 c for NA = 0.707. Due to its properties of tight focusing, the Richards-Wolf integrals have been used to study the intensity distribution of each polarization component for different kinds of incident light. And these are linearly polarized light, radially polarized light, azimuthally polarized light, linearly polarized light with spiral phase, and linearly polarized light with ultrashort pulses. From comparisons of numerical results, the intensity distributions are obviously different for different kind of incident light, and accelerating superluminal laser focus with special structure (such as the hollow conical beam) can be produced under appropriate condition. We believe this study can expand the fields of application for the long-focal-depth mirror.
1 citations
TL;DR: In this paper, a new focusing method adopting an axicon for the demand of the plasma measurements in inertial confinement fusion (ICF) drivers is presented, which has almost unchanged axial intensity, a focal depth more than 3mm, beam size smaller than 100μm and the maximal relative intensity of side lobe less than 2%.
Abstract: In this paper, a new focusing method adopting an axicon for the demand of the plasma measurements in inertial confinement fusion (ICF) drivers is presented. In order to improve the performance of this element, annular-aperture and Super-Guassian apodization are introduced to remove the on-axis oscillations. Meanwhile, the lateral width is optimized through choosing appropriate radius ratio of the inner ring to outer ring of the element. Furthermore, the feasibility is conformed by numerical evaluation of Fresnel diffraction integral .The results obtained are accordant with our designed intention. At last, as an example and for specific application, we designed an axicon, which has almost unchanged axial intensity, a focal depth more than 3mm, beam size smaller than 100μm and the maximal relative intensity of side lobe less than 2%. The performance of this element satisfies the requirements of plasma measurements in ICF drivers.
1 citations
References
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TL;DR: A novel aspheric holographic optical element, the holographic axilens, is reported for achieving extended focal depth while keeping high lateral resolution.
Abstract: We report a novel aspheric holographic optical element, the holographic axilens, for achieving extended focal depth while keeping high lateral resolution. The element is designed according to special optimization techniques and recorded as a computer-generated hologram. The results for a specific element, which has a depth of focus of 30 mm, a lateral resolution of 80 microm, a focal length of 1250 mm, and a diameter of 12.5 mm at a wavelength of 633 nm, are presented.
220 citations
TL;DR: The most common axicon is a flat cone as mentioned in this paper, where a small source of light on the axis of the cone is imaged into a line along a portion of the axis, and the resulting axicon telescope may be used in aligning machinery such as paper mills.
Abstract: The most common axicon is a flat cone. A small source of light on the axis of the cone is imaged into a line along a portion of the axis. In lenses the spot diagram has been useful in evaluating image quality. In axicons a corresponding line diagram where lines take the place of dots is useful. In general, axicon instruments correspond to the usual optical instruments. For example, an axicon may be used as an objective to form a telescope. The resulting axicon telescope may be used in aligning machinery such as paper mills. Similarly, an axicon autocollimator may be used to precisely set mirrors perpendicular to a line. One form of axicon microscope has been tried out for the special purpose of locating the position of shiny surfaces without touching them. A most useful form of optical aligner is the reflection cone axicon. It is used as a straight edge. One example is a reflecting cone of 6 in. diam and maximum range of 40 ft with precision of 5 or 6 wavelengths over the entire range. Another example is a 5 in. diam cone with a range of 10 ft and precisions of about 1 wavelength. In this case the use of a suitable radius for the reflecting surface had the effect of making the image brightness substantially uniform over the 10 ft range. Photo cell pickup has been shown to be successful with very high precisions of setting. This opens the way for automatic machine guiding to very high precisions.
215 citations
TL;DR: New optical combinations of axicons and axicons with spherical mirrors and lenses suitable for laser machining are presented and potential new laser applications are discussed in relation to these optical devices.
Abstract: New optical combinations of axicons and axicons with spherical mirrors and lenses suitable for laser machining are presented. Linear and annular focusing, coaxially and radially to the laser beam, are possible. Most combinations allow continuous adjustment of exit beam parameters, focal line length, focal ring diameter, and magnification, by varying the relative position of one of the axicons. Potential new laser applications are also discussed in relation to these optical devices.
175 citations
TL;DR: The purpose of this paper is to show that when a lens-axicon combination is illuminated by a Gaussian beam, the transverse distribution of the focal ring is also aGaussian distribution.
Abstract: An axicon and a lens are combined to form an optical system producing a ring-shaped pattern. The purpose of this paper is to show that when a lens-axicon combination is illuminated by a Gaussian beam, the transverse distribution of the focal ring is also a Gaussian distribution. The typical width of this distribution was found to be, in the case of the lens-axicon combination, 1.65 times greater than the typical width of the Gaussian beam obtained by focusing the same beam using the lens alone. This focusing system is well suited for the drilling of good quality large diameter holes using a high power laser beam.
144 citations
TL;DR: The specific goal is to demonstrate that high resolution and large depth can be achieved simultaneously, thus overcoming the major limitation of conventional light sectioning.
Abstract: We report a method for 3-D sensing by light sectioning. The specific goal is to demonstrate that high resolution and large depth can be achieved simultaneously, thus overcoming the major limitation of conventional light sectioning. We use the diffraction pattern of an axicon to generate a light knife with large depth of field (for example, 1700 mm) and high lateral resolution (for example, 55 μm). Illuminating an object with this light knife creates a profile on the object. We detect this profile with a CCD TV camera and evaluate the centroid of the profile by means of an interpolation algorithm.
119 citations