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Our top-selected telecentric and non-telecentric lens solutions optimised for dimensional measurement and surface inspection of aerospace fasteners and precision components.
Understanding the optical science behind modern aerospace quality assurance.
The aerospace industry operates under some of the most demanding quality standards on the planet. Every bolt, rivet, screw, and threaded insert installed on a commercial aircraft or spacecraft must meet exacting dimensional tolerances — often measured in microns. A single non-conforming fastener can compromise structural integrity, trigger costly maintenance events, or in worst-case scenarios, contribute to catastrophic failure. This reality has made automated optical inspection an indispensable pillar of aerospace manufacturing quality assurance.
While telecentric lenses are widely recognised for their distortion-free, parallel-ray imaging ideal for metrology, non telecentric lenses occupy a critical and often underappreciated role in aerospace fastener testing. These lenses offer a perspective projection model — meaning the field of view expands with working distance — making them exceptionally versatile for applications that require larger depth of field, longer working distances, or cost-effective integration into high-throughput inspection lines.
Modern non telecentric machine vision lenses, when paired with high-resolution CMOS sensors and advanced image processing software, can reliably detect dimensional deviations, surface defects, thread anomalies, and head geometry non-conformances at production speeds exceeding thousands of parts per minute. This capability is transforming how aerospace tier-1 and tier-2 suppliers approach fastener quality control.
Aerospace fastener inspection demands sub-micron measurement accuracy, 100% inline throughput, and zero tolerance for false negatives. Advanced non telecentric lens systems deliver the optical performance and flexibility to meet these requirements across diverse fastener geometries and production environments.
The global aerospace fastener market was valued at over USD 8 billion in 2023 and is projected to grow at a CAGR exceeding 5% through 2030, driven by rising aircraft production rates, fleet expansion in Asia-Pacific, and increasing adoption of lightweight composite structures requiring specialised fastening solutions. Every one of these fasteners — whether titanium Hi-Lok bolts, stainless steel rivets, or aluminium blind fasteners — must undergo rigorous dimensional and cosmetic inspection before assembly.
Historically, aerospace fastener inspection relied on manual gauging, optical comparators, and contact measurement instruments. These methods are slow, operator-dependent, and ill-suited to the 100% inspection mandates increasingly demanded by OEMs such as Boeing, Airbus, and their supply chains. The shift toward automated machine vision systems using non telecentric and telecentric lenses has accelerated dramatically since 2018, with adoption rates in tier-1 aerospace suppliers now exceeding 70% for critical fastener families.
Non telecentric lenses are particularly favoured in applications where the fastener presentation geometry varies, working distances are longer, or the system must accommodate multiple fastener sizes on a single inspection platform. Their cost-effectiveness compared to high-precision bi-telecentric systems also makes them the preferred choice for suppliers balancing quality mandates with capital equipment budgets.
Non telecentric lenses engineered for the unique demands of aerospace fastener dimensional and surface quality control.
Non telecentric designs provide greater depth of field compared to high-magnification telecentric optics, enabling reliable imaging of fasteners with varying head heights or slight positional variation on conveyor systems.
Optimised for integration with high-speed conveyor and bowl-feeder systems, supporting inspection rates of 1,000+ fasteners per minute without sacrificing image quality or measurement repeatability.
Long and adjustable working distance options allow non telecentric lenses to be deployed in diverse inspection cell configurations, from compact inline stations to large-format gantry inspection systems.
A single lens platform can accommodate bolts, screws, rivets, and inserts of varying head styles (hex, pan, countersunk, dome) by adjusting magnification and working distance parameters.
Advanced multi-element optical designs minimise barrel and pincushion distortion, ensuring dimensional measurement accuracy even at the periphery of the sensor field — critical for edge detection of fastener diameters.
Metal barrel construction with anti-vibration locking rings ensures stable focal length and aperture settings in demanding factory environments subject to vibration, temperature variation, and particulate contamination.
From raw material receiving to final assembly verification — non telecentric lenses serve critical inspection roles across the entire fastener lifecycle.
Non telecentric lenses paired with coaxial or ring illumination enable precise imaging of external thread profiles. Image processing algorithms extract thread pitch, lead angle, crest width, and root radius, comparing against AS9100 and NAS specifications. Defects such as incomplete threads, cross-threading, or surface laps are flagged automatically with sub-pixel edge detection.
Fastener head diameter, height, socket depth, and drive recess geometry are measured using calibrated pixel-to-millimetre mapping. Non telecentric lenses with low distortion coefficients deliver measurement repeatability of ±2–5µm, meeting the requirements of aerospace drawing tolerances for critical structural fasteners.
Cosmetic defects including seams, laps, folds, tool marks, corrosion pits, and plating voids are detected using high-contrast darkfield or brightfield illumination combined with high-resolution non telecentric imaging. Machine learning-based defect classifiers trained on aerospace fastener datasets achieve detection rates exceeding 99.5% with false positive rates below 0.1%.
Integrated into bowl-feeder or conveyor inspection cells, non telecentric lens systems perform 360° circumferential inspection by rotating fasteners through the field of view. Each accepted part receives a digital quality record linked to its unique identifier, enabling full traceability from raw material to aircraft installation — a requirement of AS9100 Rev D and NADCAP audit programmes.
Aerospace assembly plants use non telecentric lens-based vision systems at goods-receiving stations to perform statistical sampling or 100% inspection of incoming fastener lots from suppliers. This first-article and incoming quality control step prevents non-conforming hardware from entering the assembly flow, reducing rework costs and schedule risk.
After cadmium plating, anodising, dry film lubrication, or hydrogen embrittlement relief heat treatment, fasteners are re-inspected for dimensional stability and coating uniformity. Non telecentric lens systems with colour imaging capability can assess coating colour consistency and detect blistering or delamination that may indicate process deviations.
Selecting the right optical solution depends on inspection requirements, throughput demands, and system integration constraints.
| Parameter | Non Telecentric Lens | Bi-Telecentric Lens |
|---|---|---|
| Working Distance Flexibility | High — adjustable over wide range | Fixed working distance required |
| Depth of Field | Larger, suitable for varying part heights | Narrower, requires precise Z-positioning |
| Measurement Accuracy | High with calibration (±2–5µm typical) | Highest (±1–2µm typical) |
| Field of View | Scalable with working distance | Fixed by magnification |
| Cost | Lower — cost-effective for high-volume lines | Higher — premium metrology applications |
| Throughput Compatibility | Excellent — high-speed conveyor compatible | Good — requires stable presentation |
| Multi-Size Fastener Coverage | Excellent — one lens, multiple sizes | Limited — optimised for specific size range |
| Typical Aerospace Application | Sorting, surface inspection, receiving QC | Critical dimensional metrology, CMM replacement |
The convergence of optics, AI, and Industry 4.0 is reshaping how aerospace manufacturers inspect and certify fasteners.
Deep learning models trained on millions of aerospace fastener images are replacing rule-based inspection algorithms. Non telecentric lens systems feeding high-resolution image data to convolutional neural networks achieve defect detection sensitivities previously only possible with manual expert inspection, while operating at full production speed.
Modern inspection cells integrate 4–8 non telecentric lens and camera assemblies positioned around a rotating fastener presentation axis, capturing complete circumferential coverage in a single pass. This architecture eliminates the need for multiple inspection stations and reduces floor space requirements by up to 60%.
Inspection systems are increasingly connected to Manufacturing Execution Systems (MES) and digital thread platforms, enabling real-time quality data streaming, SPC analysis, and automatic non-conformance reporting. Each inspected fastener's dimensional and cosmetic data is stored against its unique part identifier, supporting full AS9100 traceability.
Emerging hyperspectral imaging systems using non telecentric optics enable detection of subsurface material anomalies, hydrogen embrittlement indicators, and coating chemistry deviations invisible to conventional monochrome or colour cameras — opening new frontiers in aerospace fastener quality assurance.
Compact non telecentric lens assemblies designed for cobot (collaborative robot) end-effector mounting enable flexible, reconfigurable inspection cells that can be redeployed across multiple fastener product families without major capital investment — a key enabler for low-volume, high-mix aerospace production environments.
GPU-accelerated edge computing platforms deployed directly within the inspection cell enable real-time image processing and dimensional measurement at camera frame rates, providing immediate closed-loop feedback to upstream manufacturing processes and eliminating the latency of centralised server-based architectures.
Canrill's ISO 9001:2015 certified quality management system ensures every telecentric and non telecentric lens meets the exacting standards required for aerospace fastener inspection applications.
Canrill Quality Management System conforms to the standard of ISO9001:2015 in the production of industrial telecentric lenses and accessories. Our Quality Dept consists of 13 experienced persons — more than 13% of total personnel — demonstrating the central importance of quality in Canrill's operations. The department has four independent branches: IQC, IPQC, QA, and OQC, each working autonomously to guarantee the excellent optical performance required for aerospace fastener testing applications.
Explore our full portfolio of telecentric and non telecentric lenses — from high-magnification bi-telecentric metrology optics to cost-effective line scan solutions for aerospace and industrial inspection.
Canrill's engineering team works directly with aerospace manufacturers and vision system integrators to specify the optimal non telecentric or telecentric lens solution for your fastener inspection application. Contact us for technical consultation, sample evaluation, and factory-direct pricing.