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Proceedings Paper

Thin micro lens array realizing wide and uniform illumination
Author(s): Takeshi Matsuo; Toshimitsu Takaoka; Sho Arai; Seiichiro Kitagawa
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Paper Abstract

In recent years, Time-of-Flight (TOF) camera technology is widely adopted for 3D mapping and motion gestures. TOF camera generally consists of light emitting and receiving elements. The micro lens array (MLA) which had been commercialized as a lens for light projection for TOF camera could be made of a resin with a product size of 6 x 5 x 0.85 mm while the projection range was 120 degrees and the light amount unevenness was 10 % or less.
In general, a plurality of lenses in MLA are regularly arranged, and this arrangement causes light interference. Since the light amount unevenness occurred due to the interference, the unevenness could be reduced by arranging the lenses at random in three axes. The light amount unevenness was also caused by transfer errors that occurred in the molding process. The shape error of lens was controlled to nanometer-size by developing a correction process that functioned the shape error and adapted it to mold processing. Although a high refractive resin was used to widen the projection angle, it was difficult to manufacture a thin lens by injection molding because of the high viscosity. This problem was also solved by developing a heating and cooling method in the molding process. As a result, by optimizing the lens arrangement and controlling the error of the lens shape, the light amount unevenness of projection could be suppressed to 10% or less.

Paper Details

Date Published: 28 February 2020
PDF: 8 pages
Proc. SPIE 11292, Advanced Fabrication Technologies for Micro/Nano Optics and Photonics XIII, 112921C (28 February 2020); doi: 10.1117/12.2544644
Show Author Affiliations
Takeshi Matsuo, Nalux Co., Ltd. (Japan)
Toshimitsu Takaoka, Nalux Co., Ltd. (Japan)
Sho Arai, Nalux Co., Ltd. (Japan)
Seiichiro Kitagawa, Nalux Co., Ltd. (Japan)


Published in SPIE Proceedings Vol. 11292:
Advanced Fabrication Technologies for Micro/Nano Optics and Photonics XIII
Georg von Freymann; Eva Blasco; Debashis Chanda, Editor(s)

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