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Optical Engineering • Open Access

Uncooled infrared detectors toward smaller pixel pitch with newly proposed pixel structure
Author(s): Shigeru Tohyama; Tokuhito Sasaki; Tsutomu Endoh; Masahiko Sano; Koji Kato; Seiji Kurashina; Masaru Miyoshi; Takao Yamazaki; Munetaka Ueno; Haruyoshi Katayama; Tadashi Imai

Paper Abstract

An uncooled infrared (IR) focal plane array (FPA) with 23.5 μm pixel pitch has been successfully demonstrated and has found wide commercial applications in the areas of thermography, security cameras, and other applications. One of the key issues for uncooled IRFPA technology is to shrink the pixel pitch because the size of the pixel pitch determines the overall size of the FPA, which, in turn, determines the cost of the IR camera products. This paper proposes an innovative pixel structure with a diaphragm and beams placed in different levels to realize an uncooled IRFPA with smaller pixel pitch (≦17  μm ). The upper level consists of a diaphragm with VOx bolometer and IR absorber layers, while the lower level consists of the two beams, which are designed to be placed on the adjacent pixels. The test devices of this pixel design with 12, 15, and 17 μm pitch have been fabricated on the Si read-out integrated circuit (ROIC) of quarter video graphics array (QVGA) (320×240 ) with 23.5 μm pitch. Their performances are nearly equal to those of the IRFPA with 23.5 μm pitch. For example, a noise equivalent temperature difference of 12 μm pixel is 63.1 mK for F/1 optics with the thermal time constant of 14.5 ms. Then, the proposed structure is shown to be effective for the existing IRFPA with 23.5 μm pitch because of the improvements in IR sensitivity. Furthermore, the advanced pixel structure that has the beams composed of two levels are demonstrated to be realizable.

Paper Details

Date Published: 18 December 2013
PDF: 12 pages
Opt. Eng. 52(12) 123105 doi: 10.1117/1.OE.52.12.123105
Published in: Optical Engineering Volume 52, Issue 12
Show Author Affiliations
Shigeru Tohyama, NEC TOSHIBA Space Systems, Ltd. (Japan)
Tokuhito Sasaki, NEC TOSHIBA Space Systems, Ltd. (Japan)
Tsutomu Endoh, NEC TOSHIBA Space Systems, Ltd. (Japan)
Masahiko Sano, NEC TOSHIBA Space Systems, Ltd. (Japan)
Koji Kato, NEC TOSHIBA Space Systems, Ltd. (Japan)
Seiji Kurashina, NEC TOSHIBA Space Systems, Ltd. (Japan)
Masaru Miyoshi, NEC TOSHIBA Space Systems, Ltd. (Japan)
Takao Yamazaki, NEC TOSHIBA Space Systems, Ltd. (Japan)
Munetaka Ueno, Japan Aerospace Exploration Agency (Japan)
Haruyoshi Katayama, Japan Aerospace Exploration Agency (Japan)
Tadashi Imai, Japan Aerospace Exploration Agency (Japan)

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