Fabrication and optical characterization of large aperture diffractive lenses using greyscale lithography

Aguiam, D.; Santos, Joana D.; Silva, Carlos; Gentile, Fabio; Ferreira, Carlos; Garcia, Inês S.; Cunha, João Paulo Silva; Gaspar, J.

doi:10.1016/j.mne.2022.100111

Cited by 9 publications

(5 citation statements)

References 29 publications

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“…The resulting multilevel mask is shown in Figure 4a, together with an optical microscope image of the fabricated lens. The lens optical function is confirmed through the Rayleigh-Sommerfeld integral propagation of the field along z, Figure 4b, showing a focusing distance ~19 mm, in agreement with design and experimental tests [7]. Additionally, a reflection-type multilevel computer generated hologram mask for 532 nm was computed and fabricated in grayscale photoresist, Figure 5a and 5b.…”

Section: Resultssupporting

confidence: 75%

“…grayscale lithography, as shown in Figure 3b. The software is versatile and can tackle more complex surfaces, such as an aspheric diffractive lens with f=19 mm at 1550 nm, discretized with 40 phase levels, which was fabricated via grayscale lithography in ref [7]. The resulting multilevel mask is shown in Figure 4a, together with an optical microscope image of the fabricated lens.…”

Section: Resultsmentioning

confidence: 99%

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Multilevel mask design and modelling of micro optical elements and flat optics with arbitrary optical functions

Cunha,

Aguiam

2023

International Optical Design Conference 2023

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Section: Resultssupporting

confidence: 75%

Section: Resultsmentioning

confidence: 99%

Multilevel mask design and modelling of micro optical elements and flat optics with arbitrary optical functions

Cunha,

Aguiam

2023

International Optical Design Conference 2023

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“…Hakkel et al patterned flat polymeric layers to varying thickness on top of pixels to fine tune their spectral response individually [18]. Fresnel lens for the LWIR and Short Wave Infrared have also been fabricated using GSL [19][20][21]. A thermal scanning probe has been used in grayscale lithography to achieve extremely high resolution with step heights of 6 nm and 32 nm step width [22].…”

Section: Introductionmentioning

confidence: 99%

Optimization of Grayscale Lithography for the Fabrication of Flat Diffractive Infrared Lenses on Silicon Wafers

Bouchouri,

Akram,

Øhlckers

et al. 2024

Preprint

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Grayscale Lithography (GSL) is an alternative approach to the standard Binary Lithography in MEMSfabrication, enabling the fabrication of complicated arbitrary 3D structures on the wafer, without the need for multiple masks and exposure steps. Despite its advantages, GSL’s effectiveness is highly dependent on controlled lab conditions, equipment consistency, and finely-tuned photoresist exposure and etching processes. This works presents a thorough investigation of the challenges of GSL for Silicon (Si) wafers and presents a detailed approach on how to minimize the fabrication inaccuracies, aiming to replicate the intended design as closely as possible. Utilizing a maskless laser writer, all aspects of the GSL as analyzed, from photoresist (PR) exposure parameters to Si etching conditions. A practical application of GSL is demonstrated in the fabricationof 4 μm deep Silicon Fresnel Lenses for Long Wave Infrared imaging (8-12 μm). The surface topography of a Fresnel lens is a good case to apply GSL as it has varying shapes and size features that need to be preserved.. The final fabricated lens profiles show good match with the initial design and demonstrate successful etching of coarse and fine features and demonstrating images taken with an LWIR camera.

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“…Grayscale in microfabrication refers to a technique where varying levels of gray shades are used to create three-dimensional (3D) structures with height variations on a substrate [ 43 ]. Laser lithography is the most commonly used method for grayscale patterning, where a UV laser beam is used to pattern a photosensitive material (photoresist) coated on the surface of the substrate.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Spiral Low-Cost Microchannel with Trapezoidal Cross Section for Cell Separation Using a Grayscale Approach

et al. 2023

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Trapezoidal cross-sectional spiral microfluidic channels showed high resolution and throughput in cell separation in bio-applications. The main challenges are the complexity and high cost of the fabrication process of trapezoidal cross-sectional channels on the micro-scale. In this work, we present the application of grayscale in microfluidic channel design to overcome the complexity of the fabrication process. We also use direct engraving with a CO2 laser beam on polymethyl methacrylate (PMMA) material to drastically reduce the microfluidic chip’s cost (to <30 cents) and fabrication time (to 20 min). The capability of the present fabrication methodology for cell sorting applications is demonstrated through experimental tests for the separation of white blood cells (WBCs) from whole blood at different dilution factors. The experimental results indicated that an 800 µL/min flow rate provided the optimal separation efficiency using the fabricated chip. A 90.14% separation efficiency at 1% hematocrit diluted blood sample was reported.

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Fabrication and optical characterization of large aperture diffractive lenses using greyscale lithography

Cited by 9 publications

References 29 publications

Multilevel mask design and modelling of micro optical elements and flat optics with arbitrary optical functions

Multilevel mask design and modelling of micro optical elements and flat optics with arbitrary optical functions

Optimization of Grayscale Lithography for the Fabrication of Flat Diffractive Infrared Lenses on Silicon Wafers

Fabrication of Spiral Low-Cost Microchannel with Trapezoidal Cross Section for Cell Separation Using a Grayscale Approach

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