Hot embossing method for development of soft glass microoptic components with broadband infrared transmission DOI:10.15199/ELE-2014-205
Recently we have witnessed a dynamic progress in research
and applications of optoelectronics within the infrared (IR) spectrum.
In this wavelength range most of the commonly used optical
materials such as fused silica glass cannot be used due to
high attenuation beyond 2 [mikro]m. There are other materials, suitable
for this range, like single crystalline germanium, zinc selenide,
chalcogenide glass or GASIR glass [1]. The main problems with
the abovementioned materials concern their fabrication, toxicity,
relatively high cost and lack of transparency within the visible light
range. Therefore it is necessary to study new materials that could
be used for the low-cost production of optical components for
mid-IR. One of the solutions are the polymer materials. They are
low-cost and easy to process, but also show low thermal durability
and variation of their optical parameters over time. A possible
alternative solution to these problems is to use heavy metal oxide
soft glasses.
One of the low-cost methods used in the fabrication of optical
elements is hot embossing [2], especially appropriate for fabricating
polymer elements. The HE method can also be used with
glass, but this involves several problems of technical kind. First,
the process requires higher temperatures 400-900°C, depending
on the composition of the glass used. Secondly, the process requires
better temperature stabilization to make the hot glass malleable
but not molten and to avoid crystallization. Thus, using soft glasses
to fabricate elements with the HE method requires a series of
tests to optimize the choice of material and the process.
Selection of glasses and materials for mold
One of the most important stages of work with a hot embossing
system is the choice of the material for the mold, as its thermal
expansion coefficient must be close to that of the molded material.
Moreover the molded [...]