Optical Fabrication

Glyndŵr Innovations offers a full turnkey package for the fabrication of large optics, from procurement to integration. The team at Glyndwr has the experience and knowledge to deliver modern optical components and subassemblies to specification, within budget and on time.

Our optical fabrication process starts with the procurement of the optical substrate material, the optical blank. We have good relationships with all the main suppliers of optical glass worldwide and can provide guidance on the specification of the optical blank on request. For larger or more challenging optics, some of our customers choose to procure and provide us with an optical blank to an agreed specification. This can shorten delivery times for the finished optic and may also be more cost-effective.  Alternatively, we can include the specification and procurement of an optical blank in the scope of any project.

Light-weighting of mirror substrates can also be provided. Light-weighting is a process whereby material is machined out of the rear face of the optics without affecting the strength, rigidity or surface form of the mirror. This technique is often used for removing mass from systems that will be airborne or to reduce thermal inertia. Light-weighting can remove greater than 80% of the optical substrate material for some applications. We have the capability to design light-weighting patterns for specific applications. We can light-weight up to 380 mm diameter in-house and can work with optical glass suppliers to produce larger light-weighted optical blanks.

read more about lightweighting

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Lightweighted optic

Modern optical blanks are most often supplied with the optical surfaces ground to a spherical or planar form. Some suppliers of optical glass have the capability to supply aspherical ground surfaces, which can lower the total cost of fabricating the finished optic. This surface will require further treatment before corrective polishing, or figuring, can occur. We have the capability to produce a range of surfaces including convex, concave, flat (planar), spherical, aspherical or freeform for most optical materials. We can verify this fine-ground optical surface to an accuracy of better than 5 µm using one or more contact measurement methods we have in-house.

For corrective polishing, an optical measurement method is needed for each of the  optical surfaces required. This test will be used to verify if the optic is finished and, if not, what error remains to be corrected on the optical surface before the piece is finished. Different  tests are required for different prescriptions of optical surface being fabricated. The verification test is interferometric and the optical test design can be as bespoke as the optical surface being fabricated. Our proposed test design for each optical surface is normally submitted to the customer as part of the bid process.

 

For the fabrication of bespoke precision optics, fabrication tooling needs to be designed and manufactured for

  • Handling the optic
  • Supporting the optic during polishing
  • Supporting the optic during final testing
  • Integration of the optic into its final cell assembly

This tooling is a specialised area of engineering and can constitute a significant portion of a fabrication project. The team at Glyndŵr has a lot of experience in the design of how to support and handle large optics. If required, our engineering team can also design the final mounting arrangement for the optic into your system.  ( link).

For small smaller optics, we usually have appropriate tooling already available. However, for larger of more complex optics, the design and manufacture of this tooling needs to be factored into the fabrication programme and project timescales.

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The optical measurement (metrology) concept, the fabrication tooling and light-weighting design are all part of the pre-production process and are best done in conjunction with each other. Much of this work can take place while the blank is being processed and delivered. The design of the support system is a natural follow-on to this work, as the team will already be familiar with the system.

Whilst we have conventional lap polishing machines in-house, polishing normally takes place on one of our CNC machines for larger optics. The fabrication process can take many weeks, depending upon the size and required accuracy of the optical surface. The fabrication process comprises one or more polishing runs interspersed with interferometric measurements in our metrology laboratory. For optics of 1m or larger, interferometric measurements are performed in-situ on the polishing machine, with the optic placed on a suitable metrology support.  read more about integration services 

Polishing   polishing

When we polished the optical surface to the desired accuracy, which can be anything down to 4nm RMS surface error, the optic is cleaned and removed from the polishing process. At this stage, a final verification report for the optic is issued to the customer. If required, we can have the optic coated to your specifications and also integrated it into its final cell or mount. This final stage can be completed in a clean room environment if necessary.

JP CAM Integration

Once complete, the optic is packed in a specialized shipping container, and delivered to the customer with a final project report .