Applications of Spatially Resolved Angle Measurement

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Components and optical systems used in the automotive sector must meet particularly high quality requirements. In the case of so-called lidar systems for environment detection, the requirements are even more demanding. Why? Because they must be highly precise, reliable and function flawlessly even under extreme conditions. The inspection system WAVOS from DIOPTIC helps to ensure that this is achieved.

DIOPTIC autonomous driving
Lidar sensors enable greater safety and comfort for the next generation of driver assistance.

Challenges of autonomous driving

Imagine you are driving your car through a wooded area at dusk. It’s drizzling, leaves are being blown across the asphalt by gusts of wind. Your vehicle has a collision warning system that suddenly kicks in. The system has detected a child in a gray hooded jacket approaching the roadway from the right about a hundred meters away. It takes quite a while before you see the child with your own eyes. And it takes even longer for you to understand how this is technically possible.

Technically, this is made possible by a lidar system for environment detection. The system sends out laser pulses and detects the backscattered light. This happens within fractions of a second and with high precision. Such light based ranging systems are usually installed in the radiator grille of cars or trucks and fitted with a protective cover. It is essential that the emission and detection of light through the protective cover is completely free of deflection. The testing of these Lidar windows must be correspondingly accurate and reliable.

DIOPTIC´s WAVOS: Spatially Resolved Angle Measurement
WAVOS cover 200 is used for the quality assurance of lidar windows.

WAVOS cover 200 – spatially resolved angle measurement

DIOPTIC has developed the WAVOS inspection system precisely for this purpose. The design of the system is based on a light source that sends collimated light through the sample and hits the sensor head on the other side. The beam deflection is measured. “This can be used to measure the topography or wavefront quality of a wide variety of optics made of plastic or glass,” explains Niklas Andermahr, “with high precision in combination with high lateral resolution and a large scanning range.”

The type of coating and the parameters of the coating process have an influence on the transmitted angular field – the picture shows different hardcoatings of polycarbonate.
The type of coating and the parameters of the coating process have an influence on the transmitted angular field – the picture shows different hardcoatings of polycarbonate.

Quality assurance for lidar systems

The WAVOS inspection system has impressively demonstrated that it is convincing in application in the quality inspection of protective windows for lidar sensors. The influence of coatings, injection molding processes as well as curved glass panes is measured with WAVOS in series productions. Automated testing is already used for 100% inspection. WAVOS cap is used to measure cylindrical components and hemispheres. WAVOS cover was developed for the inspection of planar and moderately curved specimens. Both systems can be adapted to the highest customer requirements in terms of working wavelength, specimen geometry or automated inspection cycles.

DIOPTIC's WAVOS for angle measurement with large protective sights.
The WAVOS is used to check large protective visors with regard to imaging quality.

Security visors, protective windows, dome inspection, optical crystals.

Wherever man or machine looks through a cover, spatially resolved angle measurement is important. The areas of application range from safety visors to optical doms for surveillance cameras to optical crystals. Depending on the inspection specifications, angular deflection, refractive power and prismatic errors or the wavefront are evaluated. A pass/fail evaluation, for example according to ISO 11010-14 or customer-specific criteria, is also integrated in the WAVOS software.

Refractive index variation
When testing nonlinear crystals, the refractive index variation resulting from crystal growth process is visualized.

…and what is your challenge?

“High-precision wavefront measurement of the protective covers of lidar sensors is anything but trivial,” says Niklas Andermahr. “With WAVOS, we have succeeded in reliably detecting beam deflections in the range of a few µrad with short measurement times.” The combination of large scanning range and high spatial resolution offers application possibilities for both large samples and batch inspection of multiple parts. Our claim is that with the help of WAVOS, our customers can reliably improve the quality of their products and reduce scatter in the series.

Our experts are available to help you with their excellent know-how. Please contact:
Sales Team
phone: +49 6201 960 90-20