Dual focus diffractive optical element with extended depth of focus

Uno, Katsuhiro; Shimizu, Isao

doi:10.1007/s10043-014-0107-9

Cited by 6 publications

(6 citation statements)

References 10 publications

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“…elsewhere. (10) Figure 6 shows the histogram for a daisy lens with f ′ = 250 mm, D = 3 mm, ∆f = 30 mm, M = 64, and λ = 0.632 µm, computed numerically, equation (4), and using equation (10), with very similar results.…”

Section: Model Based On An Incoherent Sum Of Standard Lenses With Dif...mentioning

confidence: 75%

“…For ∆f = 30 mm the beam width is approximately constant at focus and an EDOF is obtained. However, when ∆f = 60 mm, a dual focus is obtained instead of an EDOF, as proposed in [10]. In both cases, EDOF and dual-focus, the equation ( 6) accurately predicts the focus width for these complex lenses.…”

Section: Model Based On An Incoherent Sum Of Standard Lenses With Dierent Fociimentioning

confidence: 99%

“…where g (θ) is a periodic function in θ ∈ [0, 2π], and M is the number of periods in the 2π range (number of petals). The daisy lens is one example of this kind of DOEs [8,10]. It presents a sinusoidal variation of the focal distances…”

Section: Extended Depth Of Focus Of Diffractive Optical Elements With...mentioning

confidence: 99%

“…In this work, we analyze how diffractive lenses with a fast angular variation of focal distance, such as daisy and lotus lenses, can produce EDOF, that is, having a long depth of focus but still a narrow beam width [8][9][10][11][12]. Firstly, we analyze daisy lenses, which present a sinusoidal angular variation in the focal distance.…”

Section: Introductionmentioning

confidence: 99%

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Optimization of angular diffractive lenses with extended depth of focus

Sanchez‐Brea

Torcal-Milla

Hoyo

et al. 2020

J. Opt.

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Conventional refractive lenses concentrate the incident light at focal distance. A narrow beam waist can be achieved by increasing the lens numerical aperture, but strongly reduces the depth of focus. In this work, we explore diffractive lenses designs, with fast angular variation of the focal distance, that produce both a narrow beam waist and a long depth of focus. We predict the focusing properties of the diffractive lenses with a simple analytical model based on an incoherent superposition of standard lenses with different focal distances. The histogram of the local focal distances is used to determine the weights in the superposition. Our model optimizes the shape of the diffractive lenses, in order to extend the depth of focus, which corresponds to the lotus lens. We verify our results with numerical simulations based on Rayleigh-Sommerfeld approach. Experimentally, we validate our analytical and numerical solutions with a spatial light modulator. We have found configurations for the lotus lens where the depth of focus is significantly incremented with only a slight increment of the focal width. For example, we increased the depth of focus from 7.6 mm to 37.2 mm while the beam waist varied from 35.0 microns to 51.6 microns for a lens with diameter D = 4 mm, and focal distance f' = 125 mm. These results may find applications in the design of contact and intraocular lenses with extended depth of focus, laser focus generators, and imaging applications where extended depth of focus is needed.

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Section: Model Based On An Incoherent Sum Of Standard Lenses With Dif...mentioning

confidence: 75%

Section: Model Based On An Incoherent Sum Of Standard Lenses With Dierent Fociimentioning

confidence: 99%

Section: Extended Depth Of Focus Of Diffractive Optical Elements With...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Optimization of angular diffractive lenses with extended depth of focus

Sanchez‐Brea

Torcal-Milla

Hoyo

et al. 2020

J. Opt.

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“…Trying to solve this problem, Lotus lens was proposed. 10,11 This angular lens presents a linear variation of the focal length, and generates a non-uniform elongated beam due to diffractive effects. As a consequence, sectorized Fresnel zone plate (SFZP) was proposed, which also includes a quadratic and cubic variation of its focal length.…”

Section: Introductionmentioning

confidence: 99%

Angular extended depth-of-focus diffractive lens based on Fourier series

Soria-Garcia,

Sanchez-Brea,

del Hoyo

et al. 2023

Digital Optical Technologies 2023

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Extended depth-of-focus (EDOF) diffractive lenses produce a narrow and long focusing region which have many applications on microscopy, laser focusing or contact and intraocular lenses. Several designs have been proposed to achieve EDOF by angularly modulating the focal length. Nevertheless, when the focus is highly elongated, some undesired intensity fluctuations are produced. To solve this problem, we have generalized this type of lenses by defining their focal length as a Fourier series. Moreover, we have used Particle Swarm Optimization algorithm to optimize its Fourier series coefficients and generate an enhanced design. The performance of our Fourier Series Diffractive Lens (FSDL) is parameterized through the Full Width at Half Maximum (FWHM) of the beam and the uniformity of the intensity along the optical axis. Our results prove that the FSDL beam on the focal region is narrower and much more uniform than previous EDOF designs, showing the enhancement of the proposed EDOF lens.

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