Some radiometric properties of gradient-index fiber lenses

Rees, James D.; Lama, W. L.

doi:10.1364/ao.19.001065

Cited by 22 publications

(4 citation statements)

References 2 publications

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“…However, the total light intensity distribution was caused by the lens array structure. [18][19][20] Light rays from plural element lenses are overlapped on the image plane, as shown in Fig. 10.…”

Section: Light Intensity Distributionmentioning

confidence: 99%

Novel Projection Exposure System Using Gradient-Index Lens Array

Kobayashi

Horiuchi

2008

jjap

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A novel low-cost projection exposure system for printing rough patterns with a width of approximately 10 µm was proposed and its feasibility was verified. In the novel exposure system, a gradient-index (GRIN) lens array was used as the projection optics. The GRIN lens array projects the same-size erect image of the mask patterns onto the wafers. Therefore, arbitrary patterns on a large mask are replicated on a wafer without using a large projection lens by simply scanning the lens array across the whole mask field. Optical lithography for printing rough patterns with widths of 1–10 µm in large areas is widely applied in fabricating various micro-mechanical components. Since the production volumes are usually small, however, expensive optical lithography systems are not easily adopted for production. The new exposure system will provide new advantages for such lithography applications. When the GRIN lens array was fixed steady, line-and-space (L&S) patterns with a line width of 20 µm were printed in spite of the guaranteed low resolution specification of approximately 80 µm. In addition, up to 2.5 µm L&S patterns were locally resolved. Localized high resolution and the uneven resolution performance mainly depend on the periodical light intensity distribution corresponding to the lens array structure. This intensity distribution was greatly improved by scanning the lens array in the direction of the lens array, and averaging the intensity irregularity. By improving the light intensity distribution to be homogeneous, 10 µm L&S patterns were uniformly printed in the whole exposure area.

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Section: Light Intensity Distributionmentioning

confidence: 99%

Novel Projection Exposure System Using Gradient-Index Lens Array

Kobayashi

Horiuchi

2008

jjap

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“…The closest technical application of the refractive natural superposition compound eye can probably be found in highly symmetric one-to-one imaging systems as for instance in photo copying machines using graded index MLAs [136][137][138][139]. In photo copying machines, numerous channels of the overall array contribute to the formation of one image point in order to achieve a high light gathering power [140].…”

Section: State Of the Art Of Man-made Vision Systemsmentioning

confidence: 99%

Micro-optical artificial compound eyes

Duparré¹,

Wippermann²

2006

Bioinspir. Biomim.

155

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Natural compound eyes combine small eye volumes with a large field of view at the cost of comparatively low spatial resolution. For small invertebrates such as flies or moths, compound eyes are the perfectly adapted solution to obtaining sufficient visual information about their environment without overloading their brains with the necessary image processing. However, to date little effort has been made to adopt this principle in optics. Classical imaging always had its archetype in natural single aperture eyes which, for example, human vision is based on. But a high-resolution image is not always required. Often the focus is on very compact, robust and cheap vision systems. The main question is consequently: what is the better approach for extremely miniaturized imaging systems—just scaling of classical lens designs or being inspired by alternative imaging principles evolved by nature in the case of small insects? In this paper, it is shown that such optical systems can be achieved using state-of-the-art micro-optics technology. This enables the generation of highly precise and uniform microlens arrays and their accurate alignment to the subsequent optics-, spacing- and optoelectronics structures. The results are thin, simple and monolithic imaging devices with a high accuracy of photolithography. Two different artificial compound eye concepts for compact vision systems have been investigated in detail: the artificial apposition compound eye and the cluster eye. Novel optical design methods and characterization tools were developed to allow the layout and experimental testing of the planar micro-optical imaging systems, which were fabricated for the first time by micro-optics technology. The artificial apposition compound eye can be considered as a simple imaging optical sensor while the cluster eye is capable of becoming a valid alternative to classical bulk objectives but is much more complex than the first system.

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“…The total incident light power from the source to the semi-sphere is w = j2 J 2B0cos 0 sin 0 d 0 d q (2) And the coupling efficiency is If there exists lateral displacement between S and L1, there will be smaller numerical aperture and lower coupling efficiency. The numerical aperture of optical fiber varies with the position of incident light, as shown below…”

Section: Designing Principlementioning

confidence: 99%