Freeform Optics: current challenges for future serial production

Schindler, Christian; Köhler, Thomas; Roth, E.S.

doi:10.1117/12.2280003

Cited by 9 publications

(6 citation statements)

References 17 publications

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“…With the result in Eqs. (9) and the below Eq. (10), the position vector describing the geometry of the second surface is found in such a way that the point image P 3 is aberrationsfree…”

Section: Definition Of the Problemmentioning

confidence: 99%

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Freeform geometrical optics II: from parametric representation to CAD/CAM

et al. 2019

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Freeform optical surfaces are of great importance because of two main properties. The first is their ability to enhance the image quality of image-forming optical systems while the second is their inherent reduction in the number of surfaces in image and non-image forming optical systems. However, the main characteristic of freeform surfaces is that they lack symmetry about any spatial axis. This attribute allows describing freeform surfaces with a mathematical parametric representation. Unfortunately, parametric representation can be extremely extended. On the other hand, when describing freeform surfaces, the explicit representation is commonly preferred because of its compactness and CAD-format exportable easiness. Parametrically represented freeform surfaces can be nonetheless exported to a CAD format with no significant departure of surface shape, as shown here. The vector method presented here guarantee that the surface's sampling density be proportional to the irradiance on the surface.

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“…With the result in Eqs. (9) and the below Eq. (10), the position vector describing the geometry of the second surface is found in such a way that the point image P 3 is aberrationsfree…”

Section: Definition Of the Problemmentioning

confidence: 99%

“…A freeform surface mathematical representation has also been recently proposed [8]. Nevertheless, manufacture methods and processes evolve to obtain symmetrical and asymmetrical freeform surfaces [7,9,10]. On the other hand, freeform design methods for imaging optics have been studied and assessed a few years ago [11].…”

Section: Introductionmentioning

confidence: 99%

Freeform geometrical optics II: from parametric representation to CAD/CAM

et al. 2019

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“…Few applications of freeform surface are in microscopy, telescopes, lithography system, satellite imaging system, prostheses, etc. 3 Due to complicated shapes and geometrical features, the manufacturing of freeform surfaces requires multi-axis computer numerical control (CNC) machines. Usually, three- to six-axis CNC machines are used to generate required profile accuracies.…”

Section: Introductionmentioning

confidence: 99%

Investigations on flexible pad polishing for nano-finishing of freeform optics mold

Mishra

Burada

Karar

et al. 2020

Journal of Micromanufacturing

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The need for freeform surfaces are widely recognized in the optical, aerospace, biomedical, and automotive industries. However, the fabrication of freeform surfaces is very difficult and expensive because of the involvement of advanced, multi-axis, dedicated machining processes. In many applications, the machining surface needs further polishing to reduce the surface roughness. The main aim of this work is to investigate the flexible pad polishing process for the finishing of the freeform surface. To achieve this, a flexible pad polishing setup is developed in two-axis configuration that can be integrated with a diamond turning machine or any other computer numerical control (CNC) machine and capable to polish the conventional rotationally symmetric surfaces as well as freeform surfaces. The polishing parameters for the developed polishing head are optimized for the nano-finishing of the freeform mold surface of Stavax ESR steel. The effectiveness of the current polishing setup is demonstrated by measuring the improvement in surface roughness height and profile. Test results reveal that the improvement on the freeform surface is significant, that is, surface roughness ( Ra) reduces from 220 nm to 25 nm while keeping the profile within the desired tolerance.

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“…The ability to spatially modify and tailor metasurface properties opens new design possibilities and applications. Spatially shaped refractive index, implemented as a metasurface, , has been used to achieve more compact optical designs with superior optical properties, such as a tunable lens, , a flat achromat lens, , a chiral flat lens, and a multiwavelength flat lens. , Beyond implementing more traditional optics, such as lenses, the ability to print the local refractive index without the limitation of standard surface finishing offers the flexibility required for the emerging field of freeform optics . Patterned metasurfaces could be used to tune several surface properties simultaneously such as refractive index and hydrophobicity to obtain self-cleaning optical surfaces …”

Section: Introductionmentioning

confidence: 99%

“…8,21 Beyond implementing more traditional optics, such as lenses, the ability to print the local refractive index without the limitation of standard surface finishing offers the flexibility required for the emerging field of freeform optics. 22 Patterned metasurfaces could be used to tune several surface properties simultaneously such as refractive index and hydrophobicity to obtain self-cleaning optical surfaces. 23 However, current metasurface technology is limited with respect to large aperture optics, which requires both area scalability and durability.…”

Section: ■ Introductionmentioning

confidence: 99%

Scalable Light-Printing of Substrate-Engraved Free-Form Metasurfaces

Yoo

Nguyễn

Ray

et al. 2019

ACS Appl. Mater. Interfaces

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A key challenge for metasurface research is locally controlling at will the nanoscale geometric features on meter-scale apertures. Such a technology is expected to enable large aperture meta-optics and revolutionize fields such as long-range imaging, lasers, laser detection and ranging (LADAR), and optical communications. Furthermore, these applications are often more sensitive to light-induced and environmental degradation, which constrains the possible materials and fabrication process. Here, we present a relatively simple and scalable method to fabricate a substrate-engraved metasurface with locally printed index determined by induced illumination, which, therefore, addresses both the challenges of scalability and durability. In this process, a thin metal film is deposited onto a substrate and transformed into a mask via local laser-induced dewetting into nanoparticles. The substrate is then dry-etched through this mask, and selective mask removal finally reveals the metasurface. We show that masking by the local nanoparticle distribution, and, therefore, the local index, is dependent on the local light-induced dewetting temperature. We demonstrate printing of a free-form pattern engraved into a fused silica glass substrate using a laser raster scan. Large-scale spatially controlled engraving of metasurfaces has implications on other technological fields beyond optics, such as surface fluidics, acoustics, and thermomechanics.

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Freeform Optics: current challenges for future serial production

Cited by 9 publications

References 17 publications

Freeform geometrical optics II: from parametric representation to CAD/CAM

Freeform geometrical optics II: from parametric representation to CAD/CAM

Investigations on flexible pad polishing for nano-finishing of freeform optics mold

Scalable Light-Printing of Substrate-Engraved Free-Form Metasurfaces

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