MEMS-Boro

Inspections of aircraft components that are difficult to access pose major challenges for aviation technology. The increasing need to be able to efficiently and reliably inspect hard-to-reach and safety-relevant areas of aircraft requires innovative solutions. The high safety standards in particular make it necessary to detect even the smallest damage or deviations at an early stage. Although previous technologies offer approaches, they do not achieve the desired miniaturization and flexibility.

Conventional borescopes illuminate the entire inspection scene, but their maximum illumination intensity is limited by the need to dissipate heat in a very confined space. In addition, their size is too large for some inspections, e.g. on engines.

The technological goal of the project was to develop a high-precision borescope that enables three-dimensional measurements with a previously unattainable measuring depth. Digital data analysis should not only speed up inspection processes, but also significantly improve diagnoses.

MEMS-based 3D scanners can focus laser light on a small spot, increasing local illumination intensity and reducing dependence on surface texture. The combination of MEMS technology and laser light also offers the advantage of miniaturization compared to conventional inspection methods using borescopes, allowing more precise and faster analysis of hard-to-reach areas.

3D MEMS camera Fraunhofer ISIT is pursuing the development of a new type of 3D MEMS camera for use in borescopes as part of the joint project. The aim was to significantly increase the efficiency and safety of inspections through digitalization and miniaturization.

ISIT already has patents and developments in the field of MEMS mirrors and 3D cameras as a basis for this.

The core components of this technology are a two-axis MEMS mirror and a miniaturized laser light source.

In the planned 3D MEMS camera, the two-axis MEMS mirror is used to deflect the laser beam. The continuously emitting laser scanner is used for fast pattern projection, the deformation of which can be used to draw highly accurate conclusions about the object distance and topography via a stereo camera. The use of dynamic structured light for 3D reconstruction, supplemented by phase-modulated LiDAR systems for high-resolution depth measurements, is particularly promising. Technology with potential

This technology enables three-dimensional measurements with high lateral resolution and fast measurement speed. AI-based automated data evaluation, which can detect and classify defects, also significantly increases the degree of automation compared to the engine inspection processes that are currently still carried out manually.

One focus of the ISIT project was to develop the high-performance MEMS mirror, which is suitable as a laser deflection system in the borescope for scanning the surface to be inspected. The aim was to develop a scanner that fits into the final borescope head in a miniaturized size, has the largest possible field-of-view and also enables all other parameters that the borescope should meet, such as pixel resolution and position determination.

Two concepts for laser integration were investigated for the development of the miniaturized laser light source: The first variant places a laser diode and other optical components such as lenses and prisms in the borescope head, while the second variant uses fiber optics.,

The projected pattern can be shifted dynamically, which helps with edge detection and improves measurement accuracy. Time flight or phase shift methods can be integrated into the borescope, which promises improved lateral and depth measurement accuracy.

The planned MEMS scanner-based borescope will ultimately have a diameter of less than 8 mm and cover a field of view of 50° x 30° – dimensions that have hardly been achieved with previous solutions. 

The successful implementation of the project is largely based on the close cooperation between the partners. IT Concepts GmbH, the Hamburg University of Technology (TUHH) - Institute of Aircraft Production Technology, 3D.aero GmbH, Leder Elektronik Design GmbH and the Fraunhofer Institute for Silicon Technology (ISIT) are involved.

The project is funded by the Federal Ministry of Economics and Climate Protection (BMWK), Aviation Research Division (LuFo).