Hard Lessons in Optical Design


GettyImages-1033277722 (1)In the fast-moving industry of optics, there are often problems that arise and need to be dealt with immediately in order to keep production running smoothly and on schedule. Whether they occur in the design, manufacturing, or assembly stage, problems can prove to be catastrophic if not handled properly. Below, we touch upon a few real issues in all three of these stages of optics and give some advice on how to keep your operation running efficiently.


Design and Manufacturing:

During the design and manufacturing stages of optical assemblies, it is important to understand the reality of lead times. In the optics industry it may take weeks or even months to receive a custom component. The process by which optical-grade glasses and crystals are created can be time-consuming. Keeping a project on schedule and establishing a consistent supply chain both depend on having the optical elements you need.

Not having reliable inventory management can extend your lead times and cause you to miss target dates. It is generally not difficult to fulfill standard, off-the-shelf components, but it can be difficult to find complicated components if your orders continuously change. Even standard off-the-shelf items can experience a spike in demand causing an unexpected delay. It is key to build a reliable relationship with your supplier and have enough stock of the parts you continuously use. Having good communication with your vendor (through monthly or quarterly forecasts) will help prevent surplus or shortages of your parts, saving you time and money. To protect your optics supply chain, Ross offers inventory management solutions such as blanket purchase orders and vendor-managed inventory.


Understand the Application:

When designing an optical system, it is important to gather as much information as possible about where and how the system will be used. When a customer asks for a system to be created, they often ask for something they do not need. Understanding how the system will be used will allow you to design a system that works ideally in their application, rather than building something that meets every performance specification, but doesn’t work as intended. This will save you time in the long run when designing and manufacturing the final product.

Many less experienced designers will simply modify an existing design or drawing without understanding the real implications of unnecessary specifications. Specifications such as surface roughness add to the cost and delivery schedule. Not only can it be over-specified, but if there is a specification, then it must be measured and not every manufacturer has every piece of metrology equipment. Specifying an overly tight wavefront requirement also adds to the cost and schedule because it takes longer to polish to smaller specifications and yield factors decrease.

Additionally, applying a wavefront spec from a 25 mm diameter optic to a 100 mm or larger optic can create many production issues. This is where having some experience or knowledge of mechanical structures is helpful. There are mechanical forces impinged on an optic during polishing and if the part flexes, this will cause wavefront and surface quality issues and drastically increase production time and cost.



When creating an optical design, the assembly process often takes a back seat in the design process. This can pose a big problem when it becomes time to assemble your product due to the dominating cost of the assembly process. It is important to consult with your assembly technicians about the design before it begins being built. They have the knowledge to identify any possible alignment or assembly issues that may arise down the road. Very rarely are optics manufactured so they can simply be put into an assembly and be aligned. There are issues of tilt/decenter and focus which, at a minimum, need to be addressed. Retaining rings seem like a great answer, but there can be issues with those as well when it comes to tightening the ring against the optic. Sometimes the optic can be rotated or tilted unexpectedly which may cause performance degradation. This is where serious thought must be given to adhesives, especially cure type, outgassing, Knoop hardness, etc., and the environment the assembly will experience.

Having good communication between your technicians and engineers is crucial in the assembly process. A lot of times, once a preliminary design is created, opto-mechanical engineers aren’t consulted about positioning and performance tolerances. Without their expertise, the cost or size of mounts may fall outside of the system’s specifications or budget.

At the end of the day, the only metric of success that matters is whether the optical system you have designed works as intended once it is completely built. Ross Optical is much more than an optical supplier, we help guide you through every step, from concept to assembly, to help you create the optimal optical system with minimal issues along the way.

Interested in more tips? Download our tip sheet: 

Optical Design Secrets: A Ten Point Checklist for Expert Optical Design

Our checklist outlines a design process that ensures that every optical system you create meets performance specifications and is delivered on time and under budget.

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