Case Study: High-Precision Optical Domes for Extreme Conditions

Optical domes, also known as dome windows, are specialized components used in a variety of optical detection and imaging systems. These domes, which feature two curved surfaces, allow light to pass through with minimal optical distortion. Typically crafted from robust materials such as sapphire, fused silica, and tempered BK7 glass, optical domes are designed to protect sensitive optical equipment, including cameras, lenses, and sensors.

Due to their shape, optical domes provide a wider field of view compared to flat ports. This makes them ideal for applications in underwater cameras, aircraft navigation systems, surveillance systems, and scientific instruments. In these contexts, optical domes not only protect the equipment but also ensure that it performs optimally.

Project Overview

Shanghai Optics undertook a project to optimize and manufacture a set of three optical domes for a research and development application. The design involved two domes with identical geometries, glued and clamped together using a titanium ring. An additional larger dome covered the smaller ones, also clamped to the titanium ring.

The laboratory environment required the domes to function under high pressure (over 3 bar) and a 60°C temperature difference. Consequently, thermal expansion of the glass was a critical consideration in material selection. Additionally, mechanical shear forces in the small clamping areas needed careful management.

One of the main challenges was ensuring the entire assembly remained intact under high pressure. The titanium ring applied a strong force, with dimensional tolerances as tight as ± 50 μm.

Key Factors in Designing Optical Domes

Coatings: Anti-reflective coatings are used to minimize reflection losses and improve optical transmission, thereby enhancing overall performance.
Material Selection: The performance of an optical dome heavily depends on selecting materials with suitable optical and mechanical properties, such as refractive index, dispersion, strength, and durability.
Curvature: The dome’s curvature impacts optical characteristics like the field of view and image sharpness. Designers must carefully balance these factors to meet the specific requirements of the application.
Mounting and Sealing: Proper mounting and sealing are crucial to protect the enclosed optical system from contamination and damage, ensuring the system’s integrity.
Environmental Resilience: Optical domes must be designed to withstand harsh environments, such as those found underwater or in aerospace, requiring resistance to pressure, temperature fluctuations, and abrasion.
Mounting and Sealing: Proper mounting and sealing are crucial to protect the enclosed optical system from contamination and damage, ensuring the system’s integrity.

Specifications of the Optical Domes

Dimension: Ø 80mm
Thickness: 4mm
Material: Chalcogenide glass
Coating: Anti-reflection Coating (<0.2%)

Addressing Challenges

Shanghai Optics’s approach to developing these specialized optical domes represents a significant advancement in protective dome technology. The project combined innovative design with rigorous testing to produce a solution that withstands high pressure and temperature extremes.

The use of materials with precise thermal expansion properties, along with a focus on mechanical shear forces and tight dimensional tolerances, highlights Shanghai Optics’ commitment to engineering excellence. Additionally, the anti-reflection coatings enhanced optical performance by reducing image clarity and transmission losses.

Shanghai Optics’ innovative assembly method, involving dual domes clamped together with a titanium ring, showcases their ability to tackle complex engineering challenges while maintaining structural integrity. This design not only improves the protective capabilities of the domes but also paves the way for future advancements in optical enclosure technology.

Through meticulous attention to detail and precision engineering, Shanghai Optics has developed a robust, high-performance optical dome solution. As optical systems continue to face more demanding environments, Shanghai Optics’ expertise ensures they remain at the forefront of providing reliable and advanced solutions for a wide range of applications.

Contact Shanghai Optics today! We’d be more than happy to discuss your projects and how to best bring them to fruition.