When designing an optical system, choosing to use stock optics or investing in a custom solution can impact performance, development timelines, manufacturing costs, and long-term scalability.
While most applications can be serviced with stock lenses, leveraging custom options can be beneficial depending on the application. In general, stock optics are ideal for prototyping, proof-of-concept work, and many low-volume production applications, while custom optics are often preferred when performance, packaging constraints, environmental requirements, or production volumes justify a purpose-built design.
Understanding the trade-offs and partnering with an experienced optical manufacturer like Ross Optical can help engineers and product developers choose the right optic based on your project requirements.
Stock vs Custom Optics at a Glance
| Factor | Stock Optics | Custom Optics |
| Lead Time | Typically available immediately or within days | Can require weeks to months depending on complexity |
| Initial Cost | Lower upfront cost | Higher engineering and tooling investments |
| Volume Costs | Usually more economical at lower volumes; fixed pricing per unit | Often becomes more cost-effective per unit as volume increases |
| Design Flexibility | Fixed materials, geometries, and coatings; may require compromises for packaging constraints | Tailored sizes, materials, and tolerances to your project requirements |
| Best Suited Applications | Rapid prototyping, low-to-medium volume manufacturing, standard R&D applications | Advanced applications, including compact medical devices, aerospace & defense, high-power laser systems, etc.; high-volume manufacturing |
What to Use for Prototyping & Proof-of-Concept
Designers and manufacturers can often benefit from stock lenses during the prototyping phase. Because catalog components are already manufactured and available for immediate shipment, engineering teams can begin testing without waiting for custom fabrication.
The two main advantages include:
- Reduced development and production time: Long lead times, often months long, for developing custom optics are eliminated. In some cases, stock lenses can be shipped overnight, enabling testing to start immediately.
- Lower upfront costs: While prototyping quantities are typically less than 10 units each, using standard stock optics provides high-cost savings.
Although in some cases, choosing standard lenses over custom involves making trade-offs in size, focal length, glass type, and available AR coatings. But they frequently provide sufficient performance to validate a concept before committing to a production design.
How Low- and High-Volume Manufacturing Differ
Low-Volume Production
For low-volume production runs, utilizing stock lenses in manufacturing yields greater benefits than custom optics. This, of course, is all contingent on material, profile, and specifications.
Typically, many laboratory instruments, research systems, prototype assemblies, consumer products, and specialized industrial and medical devices can successfully utilize catalog optics throughout the product lifecycle. Because these applications typically require relatively small quantities, the engineering, tooling, and setup costs associated with custom optics may be difficult to justify.
Key advantages of stock optics:
- Lower acquisition costs
- Simplified sourcing
- Faster replenishment
- Shorter development and qualification timelines
- Greater flexibility to modify designs during production
In many applications, stock lenses are used initially to prove concepts and test overall designs, and then some or all of the lenses would be migrated to custom designs to optimize performance or simplify the optical system. For example, aspheres can be used to eliminate a few conventional optical elements, saving weight and complexity.
Looking for a hard-to-find optical component? Explore our online optical catalog and request a quote today.
High-Volume Production
However, in the case of larger volumes of lenses, there is little benefit to using standard optics since manufacturing costs are comparable or sometimes even greater than custom options. Custom components typically require a higher upfront investment in design, tooling, and qualification, but these costs can be scheduled across larger production runs.
For many projects, a custom optical design reduced total system cost while simultaneously improving performance and manufacturability.
Key advantages of using custom optics:
- Lower per-unit costs at scale
- Improved optical performance
- Greater design control and product differentiation
- Optimized coatings and materials for the application
- Improved long-term supply chain stability
- Reduced system size, weight, and complexity
Ultimately, the decision between stock and custom optics is rarely based on volume alone. The right solution depends on a combination of production quantity, performance requirements, development timeline, and overall system cost objectives.
Key Use Case
Ross Optical reduced system complexity and cost on a particle analysis instrument.
Microtrac, an instrumentation manufacturer, approached Ross Optical after struggling to find a supplier capable of meeting the requirements for a two-wavelength optical assembly operating at both 405 nm and 780 nm. The original design required a two-lens configuration, but maintaining coating performance within tolerance proved challenging.
Rather than simply reproducing the existing design, Ross engineers evaluated the application and developed an alternative approach: a single optical element featuring a specialized dual-band coating. The result was an optical assembly that achieved just 0.1% surface reflection at both wavelengths, while reducing the total number of components in the system.
Read About the Ross Advantage Across Industries
Get the Best of Both with Custom Coating on Stock Optics
Not every application requires a fully custom optical component. Uncoated stock optics can be manufactured without a coating and later be coated with a specific custom coating to meet specifications. This approach allows engineers to leverage readily available optics while gaining the performance benefits of a customized solution.
Custom optics require dedicated manufacturing processes, and each production step has associated setup costs, lot sizes, and yield considerations. As a result, manufacturers often produce more parts than the final quantity required to account for process variation and yield losses.
Additionally, because coating chamber setup costs are largely fixed and production yields must be factored into every run, fully custom optics often require additional parts to achieve the desired finished quantity. When using a stock optic, even if the coating run does not go as planned (stuff happens), it is easier to grab another lens and try again than to manufacture new custom optics.
When This Approach Makes Sense:
- A standard lens geometry meets optical requirements
- Performance improvements are primarily coating-related
- Quantities are relatively low
- Development schedules are aggressive
- Prototype and production requirements may evolve over time
Ross has an extensive selection of standard (and hard-to-find) optics and custom capabilities.
Don’t know which one to choose? Our experts can provide input regarding manufacturability, different cost-saving approaches, and which of our partners are best at producing specific types of optics, both domestically and offshore.
Browse our optical catalog, or discuss your application with our team:
