High Index Glass Ball – Smaller the Element, Bigger the Stability
Precision balls are used in the industrial sectors and optical sectors to run optoelectronic devices. These glass balls have a smooth surface and hence present a low surface to volume ratio. It weighs much less when compared to the previous iron ball bearings. It is resistant to many chemicals and abrasion. High index glass balls provide better focal length for effective coupling. They are thinner and have higher UV protection. These balls distribute stress equally and hence have a high durability. Due to its size and spherical shape, alignment and positioning of the lens can be more accurate than the conventional lens. There are many types of glass balls available.
Ruby Balls are developed from aluminum oxide and are available in the diameter sizes of 0.15mm to 8.0mm. They are resistant to all acidic chemicals. Sapphire Balls are also created from aluminum oxide and are 99.9% pure. The hardness of these glass balls is very high, which helps in transmitting ultraviolet and infrared light. They are in demand for the aeronautical and aerospace industry. Medical equipments use synthetic saphire balls, since it has high thermal stability. Sapphire and ruby balls are similar in their properties and are highly recommended for mechanical and optical applications. Some of the applications that use these glass balls are flow meters and bar code readers.
Ceramic balls are made from either aluminum oxide or zircon oxide. They contain the properties of both aluminum and zircon and hence are resistant to both acids and bases. Ceramic balls are used in electrical insulators and spacers. Spinel balls are made from magnesium oxide and aluminum oxide and are highly resistant to chemicals and weather conditions. They are used in precision devices, due to their high temperature and heat withstanding properties.
Half balls or hemispheres are made for smaller devices where there is a space constraint. Sapphire hemispheres with a refractive index of 1.76 and spinel hemispheres with a refractive index of 1.726 are the commonly used half balls.
Precision molding is a new advancement in manufacturing the glass balls. This method does not involve grinding and polishing. A mold is used to press the glass blank in a thermal chamber to the desired low Tg ball lens. The low glass transformation temperature property is essential during the precision molding for reducing the interaction with the mold materials.
The size of the lens requires precise equipment and a steady hand to place the lenses in the exact position in the device else it shall be lost forever!
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