Direct laser fabrication of dense microlens arrays in semiconductor-doped glass

Smuk, Andrei Y.; Lawandy, N. M.

doi:10.1063/1.372449

Cited by 18 publications

(8 citation statements)

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“…Savander demonstrated Si and glass lenses with less than 0.13 in air [17], and Jones et al fabricated Si microlens arrays for use as concentrators in a CdHgTe infrared photodetector [18]. Techniques based on laser and electron beam writing have also been used to create refractive microlenses in a variety of materials [19]- [21]. Other refractive microlens fabrication techniques include lift-off, molding, the hydrophobic method, gradient index doping, and microjet printing [22]- [25].…”

Section: A Review Of Microlens Fabrication Techniquesmentioning

confidence: 99%

Microfabricated silicon solid immersion lens

Fletcher

Crozier

Guarini

et al. 2001

J. Microelectromech. Syst.

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We present the microfabrication of a solid immersion lens from silicon for scanning near-field optical microscopy. The solid immersion lens (SIL) achieves spatial resolution better than the diffraction limit in air without the losses associated with tapered optical fibers. A 15-m-diameter SIL is formed by reflowing photoresist in acetone vapor and transferring the shape into single-crystal Si with reactive ion etching. The lens is integrated onto a cantilever for scanning, and a tip is fabricated opposite the lens to localize lens-sample contact. Using the Si SIL, we show that microfabricated lenses have greater optical transparency and less aberration than conventional lenses by focusing a plane wave of 633-nm light to a spot close to a wavelength in diameter. Microlenses made from absorbing materials can be used when the lens thickness is comparable to the penetration depth of the light. Tolerance to errors in curvature and thickness is improved in micromachined lenses, because spherical aberrations decrease with lens diameter. We demonstrate scanning near-field optical microscopy with the Si SIL and achieve spatial resolution below the diffraction limit in air by resolving 200-nm lines with 633-nm light. [648] Index Terms-Atomic force microscopy, microelectromechanical devices, micromatching, microscopy, optical imaging. I. INTRODUCTION S CANNING probes used for scanning tunneling microscopy (STM) and atomic force microscopy (AFM) characterize surfaces through local electric, magnetic, or mechanical interactions. Optical imaging below the diffraction limit is performed by scanning a subwavelength source such as a tapered optical fiber above the surface, a technique known as scanning nearfield optical microscopy (SNOM) [1]. This approach suffers from low optical throughput and difficulty manufacturing reliable apertures. An alternate and more efficient technique for high-resolution optical imaging is solid immersion microscopy. This technique uses a lens held close to a sample to improve spatial resolution by a factor proportional to the refractive index of the lens [2]. The spatial resolution of a lens without aberration is limited by diffraction of light from the lens aperture. The minimum full-width at half-maximum (FWHM) spot size is in the scalar approximation, where is the free space wavelength, is the numerical aperture, is the maximum Manuscript received November 21, 2000.

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Section: A Review Of Microlens Fabrication Techniquesmentioning

confidence: 99%

Microfabricated silicon solid immersion lens

Fletcher

Crozier

Guarini

et al. 2001

J. Microelectromech. Syst.

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“…However, most literatures only focused on circular MLA. The maximum fill-factor of a microlens with circular apertures is 78.5% for rectangular layout and 90.6% for hexagonal layout [16]. Fill-factor can also be increased by using laser direct writing or reflow techniques, which apertures are changed into non-circular forms [17,18].…”

Section: Introductionmentioning

confidence: 98%

“…The maximum fill-factor of a microlens with circular apertures is 78.5% for rectangular layout and 90.6% for hexagonal layout [16]. Fill-factor can also be increased by using laser direct writing or reflow techniques, which apertures are changed into non-circular forms [17,18]. Therefore, in our laboratory, a novel process with modified electroplating process, called gapless microlens arrays technique (PMLAT), has been developed to obtain a MLA with 100% fill-factor.…”

Section: Introductionmentioning

confidence: 99%

Design and fabrication compound diffuser film with LIGA-like process

Chen

Pan

Hwang

2011

Sensors and Actuators A: Physical

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“…In addition, most of them need precise control of exposure parameters and mold roughness. Moreover, there are some special processes by laser such as direct laser writing on semiconductor-doped glass [13], excimer laser micromachining [14], and femtosecond laser lithography assisted micromachining [15]. Direct writing technique is used to carve microstructures on the substrate, which is the most typical process, but it takes more processing time than usual processes.…”

Section: Introductionmentioning

confidence: 99%