Unambiguous 3D Surface Measurement Method for a Micro-Fresnel Lens-Shaped Lenticular Lens Based on a Transmissive Interferometer

Yoon, Do‐Young; Kim, Tai-Wook; Kim, Minsu; Pahk, Heui Jae

doi:10.3807/josk.2014.18.1.037

Cited by 4 publications

(3 citation statements)

References 28 publications

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“…5(b). As mentioned previously, because of a fundamental problem, many LC lens designs have a low fill factor [9,11,13], but with our method we could obtain a microlens array with a high fill factor of more than 95%, as shown in Figs. …”

Section: Fabrication Of the Rm Lens Arraymentioning

confidence: 73%

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Polarization-Dependent Microlens Array Using Reactive Mesogen Aligned by Top-Down Nanogrooves for Switchable Three-Dimensional Applications

Son

Kim

Park

2015

Journal of the Optical Society of Korea

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We propose a reactive mesogen (RM) lens array to obtain good focusing behavior along with a short focal plane, where the focusing behavior is switchable according to the polarization state of incident light. Polarization-dependent focusing behavior is obtained using a planoconvex RM microlens array on a planoconcave isotropic lens template. Even though the sagitta of our RM lens is high, to obtain the short focal length, the RM layer can be aligned well by introducing a top-down alignment effect, using a nanogrooved template. The optical noise due to the moiré effect generated by the nanogrooves on the surface of the planoconvex RM layer can be removed simply by overcoating a thin RM layer, which is self-aligned by the geometric surface effect, without an additional alignment process. We demonstrate a hexagonal-packed RM lens array that has a very high fill factor and symmetric phase profile, for an ideal lens.

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Section: Fabrication Of the Rm Lens Arraymentioning

confidence: 73%

“…Most of these applications require an elemental lens with a short focal length, small pitch, high sagitta, and switchable nature [6][7][8][9]. In a light-field camera, for example, a photosensor array of fine pitch and a microlens array that is vanishingly small compared to the main lens are used to obtain images at various depths.…”

Section: Introductionmentioning

confidence: 99%

Polarization-Dependent Microlens Array Using Reactive Mesogen Aligned by Top-Down Nanogrooves for Switchable Three-Dimensional Applications

Son

Kim

Park

2015

Journal of the Optical Society of Korea

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“…Modeling based researches also had been proposed recently [7][8][9][10]. And several researchers have used different techniques to measure the thin film thickness and height accurately [11][12][13][14][15][16][17][18][19][20]. However, there still remains ambiguity in detecting surface height due to the thin film effect.…”

Section: Introductionmentioning

confidence: 99%

Thickness and Surface Measurement of Transparent Thin-Film Layers using White Light Scanning Interferometry Combined with Reflectometry

Kim

et al. 2014

Journal of the Optical Society of Korea

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Surface profiling and film thickness measurement play an important role for inspection. White light interferometry is widely used for engineering surfaces profiling, but its applications are limited primarily to opaque surfaces with relatively simple optical reflection behavior. The conventional bucket algorithm had given inaccurate surface profiles because of the phase error that occurs when a thin-film exists on the top of the surface. Recently, reflectometry and white light scanning interferometry were combined to measure the film thickness and surface profile. These techniques, however, have found that many local minima exist, so it is necessary to make proper initial guesses to reach the global minimum quickly. In this paper we propose combing reflectometry and white light scanning interferometry to measure the thin-film thickness and surface profile. The key idea is to divide the measurement into two states; reflectometry mode and interferometry mode to obtain the thickness and profile separately. Interferogram modeling, which considers transparent thin-film, was proposed to determine parameters such as height and thickness. With the proposed method, the ambiguity in determining the thickness and the surface has been eliminated. Standard thickness specimens were measured using the proposed method. Multi-layered film measurement results were compared with AFM measurement results. The comparison showed that surface profile and thin-film thickness can be measured successfully through the proposed method.

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Critical dimension measurement of transparent film layers by multispectral imaging

Kwon¹,

Kim²,

Jo³

et al. 2014

Opt. Express

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An optical microscopy system as a non-destructive method for measuring critical dimension (CD) is widely used for its stability and fastness. In case of transparent thin film measurement, it is hard to recognize the pattern under white light illumination due to its transparency and reflectance characteristics. In this paper, the optical measurement system using multispectral imaging for CD measurement of transparent thin film is introduced. The measurement system utilizes an Acousto-Optic Tunable Filter (AOTF) to illuminate the specimen with various monochromatic lights. The relationship between spectral reflectance and CD measurement are deduced from series of measurement experiments with two kinds of Indium Tin Oxide (ITO) patterned samples. When the difference of spectral reflectance between substrate and thin film layers is large enough to yield a large image intensity difference, the thin film layer can be distinguished from substrate, and it is possible to measure the CD of transparent thin films. This paper analyzes CD measurement of transparent thin film with reflectance theory and shows that the CD measurement of transparent thin film can be performed successfully with the proposed system within a certain wavelength range filtered by AOTF.

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Unambiguous 3D Surface Measurement Method for a Micro-Fresnel Lens-Shaped Lenticular Lens Based on a Transmissive Interferometer

Cited by 4 publications

References 28 publications

Polarization-Dependent Microlens Array Using Reactive Mesogen Aligned by Top-Down Nanogrooves for Switchable Three-Dimensional Applications

Polarization-Dependent Microlens Array Using Reactive Mesogen Aligned by Top-Down Nanogrooves for Switchable Three-Dimensional Applications

Thickness and Surface Measurement of Transparent Thin-Film Layers using White Light Scanning Interferometry Combined with Reflectometry

Critical dimension measurement of transparent film layers by multispectral imaging

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