Optical domes are crucial in many optical systems, shielding fragile components from hostile environments.
Capturing high-quality photographs of deep-sea organisms requires a delicate underwater camera capable of producing high-resolution imagery. However, the camera also needs protection to withstand the extreme pressure deep beneath the ocean.
Mounting optical components on a rapidly moving dome presents different challenges. Although pressure may not be as much of an issue, a hostile environment is still a concern. Winds, dust, and frozen snow may attack the precision optical system, yet it remains essential to maintain visibility.
An optical dome must ensure a clear, scratch-free surface under demanding conditions.
A protective dome can shield delicate optics on drones. Image Credit: Avantier Inc.
Applications and Types of Optical Domes
Custom domes can be protected in various applications, including aerospace and defense, underwater imaging, and remote sensing.
They can be found on Mars Rovers, solar radiation sensors, and undersea portals. They protect fragile equipment from water, wind, radiation, debris, toxic gases, and pressure.
An optical dome is made of transparent material with a concave internal surface and a convex exterior surface. It is carefully built so that the internal and exterior surfaces are parallel and uniformly spaced. Consider them monocentric shells with a constant thickness between the inside and outside radii.
Optical Dome. Image Credit: Avantier Inc.
Optical Dome. Image Credit: Avantier Inc.
This involves some important optical engineering. Though the optical materials used in a dome are chosen for the optimal index of refraction for a particular application, the index of refraction will not be the same as air.
With a parallel surface, the optical aberration induced by the dome can be minimized, achieving a result like invisible protection.
Durable and high-performance dome-shaped optical components can be made from various substrates, including zinc sulfide, zinc selenide geranium, UV-fused silica, glass, and sapphire. Sapphire is particularly useful for infrared sensors, such as defense applications.
It is also incredibly hard, mechanically stable, and scratch-resistant. UV fused silica is an excellent choice for transmitting or receiving UV light and protecting UV radiometers.
Key Benefits of Optical Domes
Optical domes and flat windows are made of transparent materials. For many purposes, however, an optical dome is a better option. Some reasons include:
- Optical domes give a wide field of vision, allowing sensors to detect radiation from multiple directions.
- Dome-shaped optical components have lower chromatic aberration than flat windows toward the edge of the field of view.
- Dome windows reduce visual aberration in aquatic environments compared to thicker, flat windows.
- Optical domes are better suited for pressure resistance applications than flat windows due to their uniform pressure distribution. This means the dome is substantially thinner than a flat window with the same pressure resistance, and optical aberrations are decreased.
H-K9L Optical Dome (φ60 mm). Image Credit: Avantier Inc.
Sapphire Optical Dome (φ20 mm). Image Credit: Avantier Inc.
JGS1 Optical Dome (φ110 mm). Image Credit: Avantier Inc.
Custom Optical Domes. Image Credit: Avantier Inc.
Additional Advantages of Optical Domes
Other advantages of domes will vary depending on the substrate used. Avantier manufactures custom optical domes from a wide range of substrates. Its clients often want domes that feature the following:
- Scratch resistance
- Chemical resistance
- Thermal and mechanical stability
- Ease of maintenance
An optical glass dome is the optimum option for many purposes. These domes have an excellent cost-performance ratio and are robust and simple to maintain. They are scratch-resistant, chemically resistant, temperature-stable, and easy to clean. Anti-reflection coatings and other protective coatings can be added as needed.
While acrylic optical domes are not as scratch-resistant as glass, they are mechanically stable and resistant to fracture. It will also be lighter and less expensive to manufacture.
This information has been sourced, reviewed and adapted from materials provided by Avantier Inc.
For more information on this source, please visit Avantier Inc.