What is an opto-mechanical sub-system?
Opto-mechanical sub-systems combine optical components like lenses, mirrors and prisms with mechanical elements. They are often used in complex environments in markets like defence and life sciences. They can be static (mounted) or integrated in a moving mechanical system where micro-positioning is required. A good example of this would be in an imaging or laser system where light needs to be manipulated with high accuracy and repeatability.
Why is process control so important in the production of opto-mechanical systems?
Opto-mechanical sub-systems are highly complex and sensitive to a range of environmental factors. They typically have incredibly tight micron-level tolerances and being able to achieve repeatable precision is of paramount importance. Even small errors can magnify and have a big impact on the performance of the wider system or instrument.
Opto-mechanical systems are highly sensitive to temperature, humidity and vibration as well as contamination. Their components are easily damaged, and they typically use more expensive, specialised materials which adds a layer of complexity when it comes to handling.
The complicated nature of opto-mechanical systems means that access to skilled engineers as well as specialist manufacturing, assembly and test facilities is required. Overlaying all of this is the need for effective process control which is central to ensuring that technical, operation and commercial requirements can be consistently met. The ability to combine the skills and knowledge of people, advanced manufacturing equipment and effective process control can become a real source of competitive advantage for a supplier.
What measures can be put in place for process control?
Process control refers to the methods, systems and technologies used to regulate and monitor production so that operations run predictably and deliver products that consistently meet specification. This ensures that the sub-system and the wider system or instrument perform as expected. There are a number of process control measures that can be implemented to achieve this:
Early Involvement and New Product Development and Introduction
Ensuring that all companies within an instrument’s supply chain have a deep understanding of the final application is key to making sure that suitable sub-systems, components and processes are developed. For example, we find that by fully appreciating the interaction of optical and mechanical elements, we can ensure the accurate positioning and robust performance of the optics in the mechanical environment. This approach is particularly effective if we are involved early on in development as it allows us to create bespoke processes, tooling, custom test equipment and helps us to anticipate and mitigate challenges that may be faced during assembly. This development work takes place in our specialist NPDI facility, Gemini Works, where technology is fully developed and proved out before it is transitioned into production.
Precision Cleanroom Assembly
Opto-mechanical sub-systems are assembled in a cleanroom environment which has been specifically designed to help avoid contamination. There are different classifications of cleanroom. The most commonly used standards in the UK and EU are ISO 14644-1 and ISO 14698, where ISO 1 is the cleanest environment. Our Optical Cleanroom is certified to ISO 7 and is supplemented by laminar flow cabinets to ISO 4. The rooms also hold certification to BS EN 61340 ensuring effective protection for sensitive electronic devices against electro-static discharge. The engineers who physically assemble the systems are equally as important as the environment they operate in. They must assemble to micron-level tolerances whilst protecting the cleanliness of the room by adhering to the necessary disciplines and processes for working with precision optics. All of our engineers follow standard processes and can suggest improvements which are reviewed by the owner of the process.
Effective Optics Handling and Inspection
Optics must be handled carefully and should be inspected before they are integrated into the wider mechanical assembly. Upon receipt of optics, we perform inspection to customer requirements. In some cases, we perform sampled inspection but for other customers, we inspect 100% of received components. Our disciplines, procedures and equipment are also pre-approved by the customer to ensure the optical components are not subject to latent failure during their working operation. Non-contact handling and measurement devices are used, including vacuum pens and optical CMM equipment. Bespoke tooling is designed and manufactured in-house, ensuring accurate positioning of optics to +/- 0.05mm, and assembly disciplines are carefully controlled in order to protect the optic coatings. Vacuum de-gassing ovens are also used to protect the assemblies from out-gassing when in use, which may cause performance degradation in laser-based systems.
Training
Continuous training is important for the skilled engineers and technicians who are handling delicate optical components. Training helps to maintain a highly skilled workforce who can adapt to new technologies, follow processes correctly, suggest process improvements and understand the importance of maintaining a quality culture.
Testing and Inspection
Testing, whether that is in-process or validation testing, is an important part of the production process. At Reliance, testing is undertaken to customer specification, often using bespoke test equipment designed and built in house. This allows us to check the movement of the optic as part of the overall mechanical assembly, including verification of optic positioning and optic movement.
Cleanroom to Cleanroom Delivery
All sub-systems eventually need to be combined into a wider system or instrument. It’s important that they can be seamlessly integrated and that no damage or contamination occurs in transit. At Reliance, opto-mechanical assemblies are packed within the cleanroom in high integrity packaging and delivered directly to the point of use – from cleanroom to cleanroom – straight into the next stage of the customer’s assembly process.
Conclusion
Process control is the foundation on which reliable, high-performance opto-mechanical systems are built. With the cost of non‑conformance potentially high, combining the world class expertise, infrastructure and process control is essential to safeguarding system integrity and ensuring that every component performs as expected. In an industry where high performance is non‑negotiable, process control becomes more than just an operational requirement; it is the key to unlocking customer success and competitive advantage.
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Reliance Precision has decades of experience in the assembly of defence, space and life science sub-systems. Please contact us to discuss how we can support your mission or process critical goals.
