Windows are optical glass with ground and polished faces that are relatively parallel.They are used to isolate two physical environments while allowing light to pass.Windows made of BK7 material have high transmission in the visible spectral region, do not scratch easily, do not degrade under normal operating environment and hence do not need any special precaution or treatment. Anti-Reflective Coating will provide higher transmission. Specification of our optical windows as follow: Round Optical Window,Optical Infrared Window,Optical Square Window,Irregular Window,Optical Flat Window China Star Optics Technology Co.,Ltd. , https://www.csoptlens.com
When selecting windows, you should consider the following: material,transmission,scattering,wave front distortion,parallelism and resistance to certain environment.
China Star Optics offers all types of windows made from different materials.Special size and materials are also available upon request.In addition, we provide a variety of single layer or multiplayer anti-reflecting coating on Optical Windows.Â
*Material: BK7,UV-grade fused silica (JGS1) or other optical crystals materials
*Length tolerance:+/-0.01
*Width tolerance:+/-0.01
*Center thickness tolerance:0.005mm
*Surface quality:80-50 to 10-5 Scratch/Dig
*Surface flatness:<lambda to lambda/20
*Parallelism<=1min -- 2sec
*Clear Apenture:80% -- 100%
Tian Huang Appreciation Method
Tian Huang, as the name implies, refers to a type of yellow stone found in Shoushan Tiankeng. In general, the production of Tian Huang is relatively high, and there are many old yellow stones and seals that have been passed down through generations. However, it's important to note that the quality of Tian Huang varies greatly, and so does its value. Not all pieces can be considered top-grade, but those that meet certain standards are highly collectible and worth significant investment.
To truly appreciate a top-grade Tian Huang stone or seal, several key characteristics must be met:
**Color:** The most obvious feature of Tian Huang is its color—yellow. As the national color of China, yellow symbolizes royalty and power. A genuine Tian Huang should display a bright, vivid yellow, similar to gold in luster. If the stone has an outer layer, such as a "silver bag with gold" or "crow skin" pattern, there should be a clear contrast between the yellow and white or black areas. Stones with dull, murky, or unclear colors, even if they have good texture and size, cannot be classified as top-grade.
**Quality:** The quality of Tian Huang is typically judged by the "six characteristics"—fine, clean, warm, moist, condensed, and greasy. Top-grade stones should be smooth, transparent, pure, and delicate, with a glossy sheen. When held in hand, they should feel soft and tender, like the skin of a baby. Even without being treated, they should remain moist and not dry. Additionally, the texture should be refined, with minimal lines and a thin, fine outer layer if present.
**Shape:** While square and tall shapes are generally preferred for stones or seals, Tian Huang often comes in oval forms due to its natural formation. Ideally, it should be well-proportioned, round, and regular. Stones that are short, small, thick, angular, or irregular in shape are not considered valuable. In terms of design, smaller and elegant pieces are more desirable than large and ordinary ones.
**Workmanship:** Lastly, a top-tier Tian Huang must also showcase skilled craftsmanship. As the saying goes, "Jade is not just a stone; it needs to be shaped." Even the best raw material won't be valuable unless it's properly carved. A beautifully crafted piece adds immense value, making it a true masterpiece rather than just a fine stone.
In summary, Tian Huang is more than just a colored stone—it's a cultural treasure, requiring attention to color, quality, shape, and artistry to be fully appreciated.