Use Cases

Developing a 200 mm Glass Encoder Disc for a High-Resolution Rotary Encoder System.

A European manufacturer of precision rotary encoders approached Selba with a requirement that fell outside the capabilities of their existing supply chain: a glass encoder disc with a diameter of 200 mm, combining the optical graduation accuracy of a standard photolithographic process with the mechanical rigidity needed to survive integration into a large-format industrial encoder assembly.
At 200 mm diameter, conventional flat glass substrates of the thickness required for the graduation process presented an unacceptable risk of flexure and fracture during handling, assembly, and operation — compromising both the integrity of the graduation pattern and the long-term reliability of the assembled encoder. Standard edge profiles were insufficient to address the stiffness requirement without increasing substrate thickness to a point that conflicted with the customer’s mechanical envelope.
Selba’s R&D and glass machining teams developed a dedicated machining process incorporating a chamfered edge profile around the full disc perimeter. The chamfer geometry was designed to redistribute mechanical stress at the disc boundary, significantly increasing resistance to flexure and impact without adding substrate mass or altering the optical graduation area. The process required the development of custom tooling parameters within Selba’s in-house glass machining department to maintain precise concentricity between the chamfered profile and the photolithographic pattern — ensuring that mechanical processing introduced no positional error into the graduation.
The resulting disc met the customer’s resolution, signal quality, and dimensional requirements while delivering the structural robustness necessary for reliable operation in an industrial environment. The chamfered glass process developed for this programme has since been integrated into Selba’s standard capability offering for large-format encoder disc applications.

Supporting Doctoral Research Across Multiple Disciplines — A Leading European Research Institute.

Selba has established a long-running supply relationship with a prominent European research institute, providing film photomask production support to doctoral researchers working across a broad spectrum of advanced scientific disciplines. The collaboration spans multiple research groups and applications — including photonics, microfluidics, bioelectronics, and precision optics — reflecting the versatility of Selba’s film photomask capability and its ability to respond to the highly varied and often rapidly evolving requirements that characterise academic research environments.
Doctoral researchers present a distinctive set of supply challenges. Project timelines are tight, design iterations are frequent, and the range of pattern geometries, feature scales, and substrate formats requested varies significantly from one research group to the next. Standard catalogue products are rarely adequate — each film typically corresponds to a unique experimental design, produced in small quantities and often revised as the research progresses. At the same time, the scientific validity of experimental results depends directly on the accuracy and consistency of the photomasks used to fabricate the test structures and devices under investigation.
Selba’s R&D team reviews every submitted artwork file before production, regardless of volume or application — assessing feature geometries and critical dimensions against the photolithographic process the researcher intends to use. This review has proven particularly valuable in an academic context, where researchers are frequently operating at the limits of their exposure equipment’s capability and benefit from the input of an experienced process engineering team before committing a design to film. In several instances, the pre-production review has identified feature geometries that would not have resolved correctly under the researcher’s exposure conditions, allowing the design to be adjusted before production — avoiding wasted experimental cycles.
Films are produced at up to 50,800 dpi and shipped within 24 hours of artwork approval, a turnaround that accommodates the time-sensitive nature of experimental programmes operating within academic project schedules. The breadth and consistency of Selba’s support across research groups has made it a trusted production partner embedded in the institute’s research workflow — relied upon not only for film supply, but for the process expertise that comes with it.

Fast-Turnaround Optical Wafer Machining for a Global Photonics Manufacturer.

A globally active photonics company specialising in high-performance laser and illumination solutions required a machining partner capable of processing optical glass wafers at the turnaround speeds demanded by its production programme. Standard suppliers were unable to meet the combined requirements of geometric precision, edge quality, and delivery speed — wafers needed to be cut and profiled to tight dimensional tolerances while preserving the surface integrity essential for subsequent optical processing steps.
Selba developed dedicated tooling parameters for the customer’s wafer geometry and substrate material, with particular attention to edge condition and surface finish throughout the machining sequence. First-article validation was completed rapidly thanks to Selba’s integrated engineering and production environment. Machined wafers were dimensionally inspected before each shipment, with turnaround consistently meeting the customer’s production schedule.
Selba continues to supply machined wafers to the customer as an ongoing production partner, providing the precision and delivery reliability that photonic component manufacturing demands.