An optical dome is a transparent, protective enclosure that is designed to house and protect optical instruments and sensors from environmental conditions while allowing light or electromagnetic waves to pass through with minimal distortion. These domes are typically used in applications such as underwater cameras, surveillance cameras, environmental monitoring instruments, and aerospace or satellite cameras.
The shape of the dome, often hemispherical, helps to minimize optical aberrations and protect the lens or sensor from dust, water, pressure, and other external influences.
The material used for optical domes can vary, including glass, acrylic, and other transparent materials, chosen based on factors like transparency, resistance to pressure, and optical properties to match the specific requirements of the application.
Designing an optical dome involves several critical considerations to ensure it meets the required performance criteria for its specific application. The process integrates materials science, optical engineering, and environmental considerations to optimize the dome’s functionality and durability. Here are key design considerations for an optical dome:
1. Material Selection
– Optical Clarity: Choose materials with high optical transparency in the required wavelength range to minimize light absorption and scattering.
– Material Strength: Consider the mechanical strength and toughness of the material, especially for domes used in high-pressure environments like deep-sea applications.
– Environmental Resistance: The material should resist environmental degradation from UV exposure, chemical corrosion, and temperature extremes.
– Thermal Expansion: Match the thermal expansion coefficient of the dome material with that of the housing to avoid stress and potential cracking under temperature changes.
2. Dome Geometry and Thickness
– Shape Optimization: A hemispherical shape is common for minimizing optical aberrations, but the exact geometry might be adjusted for specific optical performance requirements or to reduce drag in fluid environments.
– Thickness Distribution: Uniform thickness can help in maintaining optical performance, but in some cases, varying the thickness can optimize mechanical strength without significantly impacting optical clarity.
Reduced optical aberrations: Submersible dome windows prevent the defocus and spherical aberrations associated with thick, flat windows when used underwater.
Reduced chromatic aberrations: Underwater domes also have less chromatic aberration at the edge of the FOV, compared to flat windows.
A unique aspect of dome optics is that, ideally, a dome would be “invisible” and have no effect on the light passing through them. Invisibility of glass and acrylic domes is impossible because of the change in refractive index between the dome and the environment, but it is possible to minimize the optical effects of a dome by controlling four parameters:
Thickness: Minimizing the distance between the inner and outer surfaces means that the light passes through less material, and that reduces the effect of the dome.
Refractive index: There will be an optimal index of refraction for the dome to have the least effect on rays traveling from the exterior of the dome to the interior.
Centration: If the surfaces of a dome window are not concentric, the variation in thickness causes the window to begin to act as a lens.
Pupil position: Because the dome does affect the optical performance, it is important to design an optical system so that the entrance pupil is in the best position, which is usually at the center of curvature of the dome surfaces.
3. Optical Coatings
– Anti-reflective Coatings: Apply anti-reflective coatings to reduce reflections and increase the transmission of light through the dome.
– Protective Coatings: Hydrophobic coatings can repel water for clear vision in wet environments, while scratch-resistant coatings protect the surface from damage.
4. Mechanical Integration
– Mounting and Sealing: Design the dome to ensure a secure fit within its housing, with appropriate sealing methods to protect against water ingress and environmental conditions.
– Stress Distribution: Analyze stress distribution under operational conditions, using finite element analysis (FEA) to ensure the dome can withstand expected loads without failure.
5. Thermal and Environmental Considerations
– Temperature Effects:Evaluate the impact of temperature changes on dome material and optical properties, ensuring performance stability across its operational temperature range.
– Pressure Resistance: For underwater or aerospace applications, ensure the dome can withstand the external pressure without significant deformation that could impair optical performance.
6. Manufacturing Process
– Consider the manufacturing process (e.g., molding, machining) in the design phase to ensure the dome can be produced efficiently without compromising quality.
– Address potential manufacturing defects that could affect optical quality, such as inclusions, bubbles, or surface imperfections.
7. Testing and Validation
– Optical Testing: Perform rigorous testing to validate that the dome meets the required optical specifications, including light transmission, distortion, and aberration criteria.
– Environmental and Durability Testing: Test the dome under simulated operational conditions to assess its durability and resistance to environmental stressors.
Shape Optics Specification Of Optical Glass Dome
1, Substrate: Visible material——-Optical glass (Schott N-BK7, N-BK10, WG295,N-K5,etc.)
2, Dimension: 10mm-350mm
3, Thickness: 1mm-10mm
4, Surface Quality: 60/40, 40/20, 20/10
5, Surface fringe: 10(5)-3(0.5)
6, Coating: Antireflection (AR) Coating
7, Strenthened via heat treatment (tempering)
Here’s the updated table with our stock dome lens, please consult our sales team for the detailed specs.
| Series No. | Diameter (mm) | Height (mm) | Thickness (mm) | Convex Radius (mm) | Concave Radius (mm) |
|---|---|---|---|---|---|
| 1 | 10 | 5 | 1 | ||
| 2 | 15 | 8 | 1.5 | ||
| 3 | 24 | 12 | 2 | ||
| 4 | 24 | 13 | 2 | ||
| 5 | 25 | 12.5 | 2 | ||
| 6 | 25 | 12.5 | 4 | ||
| 7 | 25 | 14.5 | 2 | ||
| 8 | 28 | 14 | 1 | ||
| 9 | 28 | 15 | 1 | ||
| 10 | 28 | 16 | 2 | ||
| 11 | 30 | 15 | 2 | ||
| 12 | 30 | 16 | 3 | ||
| 13 | 30 | 18.5 | 2 | ||
| 14 | 32 | 10 | 2 | ||
| 15 | 32 | 10 | 4 | ||
| 16 | 32 | 17 | 2 | ||
| 17 | 32 | 17 | 4 | ||
| 18 | 36 | 18 | 2 | ||
| 19 | 38 | 19 | 3 | ||
| 20 | 40 | 20 | 2 | ||
| 21 | 40 | 21 | 2 | ||
| 22 | 40 | 21.5 | 4 | ||
| 23 | 50 | 22 | 4 | ||
| 24 | 50 | 25 | 2 | ||
| 25 | 50 | 25 | 4 | ||
| 26 | 50 | 28 | 3 | ||
| 27 | 60 | 30.8 | 13.5 | ||
| 28 | 70 | 35 | 4 | ||
| 29 | 70 | 35 | 8 | ||
| 30 | 74 | 27.2 | 6 | ||
| 31 | 75 | 37.5 | 3 | ||
| 32 | 75 | 38 | 3.5 | ||
| 33 | 80 | 40 | 4 | ||
| 34 | 90 | 45 | 12 | ||
| 35 | 100 | 50 | 2 | ||
| 36 | 100 | 50 | 4 | ||
| 37 | 100 | 50 | 5 | ||
| 38 | 110 | 55 | 15 | ||
| 39 | 127 | 30.8 | 4 | ||
| 40 | 150 | 60 | 4 | ||
| 41 | 150 | 70 | 4 | ||
| 42 | 140 | 70 | 12 | ||
| 43 | 149.07 | 70 | 15 | ||
| 44 | 170 | 170 | 6.5 | ||
| 45 | 184 | 61 | 7 | ||
| 46 | 230.00 | 79.00 | 9.00 | 120.20 | 111.20 |
| 47 | 121.00 | 53.766 | 3.50 | 62.50 | 59.00 |
| 48 | 93.50 | 43.5 | 4.00 | 47.50 | 43.50 |
| 49 | 66.24 | 24.26 | 7.00 | 35.00 | 28.00 |
| 50 | 186.60 | 87.3 | 3.50 | 93.50 | 90.00 |
| 51 | 77.00 | 25.0 | 3.00 | 45.00 | 42.00 |
| 52 | 110.40 | 37.60 | 6.00 | 60.00 | 54.00 |
| 53 | 180.00 | 50.0 | 9.00 | 110.00 | 101.00 |
| 54 | 136.9 | 60.5 | 6.00 | 69.00 | 63.00 |
| 55 | 100.70 | 41.2 | 6.00 | 52.00 | 44.45 |
| 56 | 136.00 | 50.0 | 4.00 | 75.00 | 71.00 |
| 57 | 202.00 | 76.43 | 5.08 | 107.00 | 102.00 |
| 58 | 226.00 | 87.45 | 5.08 | 118.18 | 113.10 |
| 59 | 188.00 | 94.0 | 9.83 | 93.98 | 84.15 |
| 60 | 67.92 | 29.15 | 4.00 | 39.50 | 35.50 |
| 61 | 153.50 | 61.8 | 4.00 | 80.00 | 76.00 |
| 62 | 145.80 | 47.53 | 7.00 | 80.00 | 73.00 |
| 63 | 86.00 | 24.0 | 4.00 | 52.00 | 48.00 |
| 64 | 80.00 | 26.0 | 3.00 | 46.00 | 43.00 |
| 65 | 150.00 | 75.0 | 3.00 | 75.00 | 72.00 |
| 66 | 253.80 | 64.63 | 10.00 | 160.00 | 150.00 |
By carefully addressing these considerations, Optical designers can develop optical domes that meet the stringent requirements of their applications, ensuring optimal performance and durability. Optimizing the optical design of a system that includes a dome requires a very clear understanding of the application of the system, the material properties of glasses and acrylics, and the unique optical effects of dome windows. Shape Optics sells glass and acrylic domes with diameters as small as 20 mm and as large as 200mm, and we have the optical and mechanical expertise to ensure our customers choose the best components for the entire optical system based on application and use environment. Give us a call to talk to one of our engineers and learn how.
