Multispectral glass transparent from visible to thermal infrared

Abstract

International audienceThe thermal imaging market has experienced a strong growth during the recent years due to continued cost redn. of night vision devices. The development of uncooled focal plane detector arrays is the major reason for the cost redn. Another reason is the continuous improvement of the optical soln. In this paper, we present a new multispectral material which responds to the increasing demand for optics operating simultaneously in the visible​/SWIR (Short Wave IR) and the thermal IR region. The most important properties of some glasses from the GeS2-​Ga2S3-​CsCl system are highlighted in this study. A stable compn. 15Ga2S3-​75GeS2-​10CsCl allowed the synthesis of a large glass without crystn. The refractive index of this glass was precisely measured from 0.6 to 10.4μm by using the Littrow method. The chromatic dispersion was then calcd. and compared with other multispectral materials

Ga-La-S-Se glass for visible and thermal imaging

“…Previous studies on multispectral chalcogenide glasses led to the production of Ga 2 S 3 -GeS 2 -CsCl glasses, which transmitted from 500 nm to 11 μm [9][10][11]. However, the presence of CsCl resulted in high water uptake and subsequently large losses at the O-H vibration wavelengths.…”

Moldable multispectral glasses in GeS2–Ga2S3–CsCl system transparent from the visible up to the thermal infrared regions

“…To select a stable composition, the choice was realized among several compositions presenting a large difference between the transition temperature (Tg) and the crystallization temperature (Tx). As already done with the 15Ga2S3-75GeS2-10CsCl composition [17], a specific thermal treatment monitored by DSC reveal the thermal dynamics of crystallization and complete this first criteria. The figure 1 shows the result in three steps for the 20Ga2S3-65GeS2-15CsCl composition.…”

“…The Littrow method allows a precision of at least 4.10 -4 for the measured refractive index. The chromatic dispersion can be thus calculated and compared with the ZnS [20] and the 15Ga2S3-75GeS2-10CsCl composition previously studied [17]. In the figure 3, the graphic presented the refractive index ranges of these three materials.…”