Types of Insulating Glass in Optical Elements
Optical element insulating glass has a special ability to absorb, transmit, and reflect light and heat. The use of this glass in exterior windows and glass curtain walls for buildings can achieve significant energy savings. Commonly used thermal insulation glass includes heat-absorbing glass, coated glass, and insulating glass.
How does heat-absorbing glass work?
Heat-absorbing glass increases the absorption of light due to the addition of some metal ions or other substances to the glass. These additives lower the shading coefficient of heat-absorbing glass compared to transparent glass. Thus the glass absorbs more light and solar energy than untreated glass.
Disadvantage: Heat-absorbing glass blocks some of the solar radiation in both summer and winter, as well as on the south and north sides of the building. Therefore, heat-absorbing glass reduces natural heating in the winter. The heat-absorbing glass is not selective regarding wavelengths across the spectrum, so the transmittance of visible light decreases along with the total solar radiation. This effect requires an increase in artificial lighting.
How does coated glass work?
The coating on the glass surface is one or more layers of metal, alloy, or metal compound whose purpose is to change the properties of the glass. According to different characteristics of the additives, these types of glass comprise two categories: heat-reflective glass and low-emissivity glass.
Heat reflective glass
The surface of the heat-reflecting glass is coated with a metal film and some interference layers, so that the glass products can reflect more solar radiation, achieve the effect of shading, and produce rich colors. The role is to limit the solar radiation entering the room.
Disadvantages: The thermal insulation performance of heat reflective glass is no different from that of transparent glass, so it is not suitable for laser lenses in cold areas with large indoor temperature differences, but in hot areas with strong light. Its thermal insulation effect is very good. Reflective glass can not only reflect the heat radiated by the sun, but also limit the entry of visible light, which adversely affects indoor lighting. In addition, too high reflectivity will lead to light pollution, but too low to achieve energy saving effect.
Low emissivity glass
The low emissivity (low-e) coating is applied to the glass surface by vacuum deposition. The function of the low-e coating is to reflect far-infrared radiation and effectively reduce the heat transfer coefficient of the glass high-power laser mirror group. Secondly, this coating reflects solar heat radiation and selectively reduces the shading coefficient. At the same time, compared to heat-reflective glass, low-e glass does not limit the penetration of visible light.
Disadvantages: Due to the poor strength of the film, this type of insulating glass is generally not used alone.
CRYSTECH Inc. is a global supplier of Alexandrite, KTP, GTR-KTP, RTP and KDP Q-Switch, Nd:YAG and CTH:YAG crystals, thin film polarizers, laser optics and more. The company has become one of the leading manufacturers of KTP crystal and laser components in the world. Crystech has multiple product lines and workshops for crystal growth, orienting, dicing, polishing, and coating.
To request more information or a quotation for these or any CRYSTECH products, contact IL Photonics.