TY - GEN

T1 - On the development of a flexible borescope fringe projection system

AU - v. Wrangel, Moritz

AU - Kästner, Markus

AU - Reithmeier, Eduard

PY - 2021/6/20

Y1 - 2021/6/20

N2 - The 3D measurement of the interior of hollow technical bodies is still a challenge for state-of-the-art measurement systems. This is especially true for complex industrial free-form objects inside confined spaces. Fringe projection enables accurate and fast 3D measurements of object surfaces. To fulfill the task of geometric inspection of confined spaces, we have developed an endoscopic and flexible fringe projection system. The fringe patterns are generated with a RGB LED projector. Fibre-coupling of the structured light is achieved by using a microscope lens and bundle of coherent image fibres. A compact sensor head can be achieved by using a micro-objective for projecting the fringes and a Chip-on-Tip camera to capture the images. A micro lens with a diameter of 1.7 mm was used as the projector lens and a 2 megapixel 1/6” chip was used as the image sensor. By synchronizing the projector with the camera, the system is capable of capturing up to 10 grayscale patterns per second. The measurement volumes result to approximately 20 × 13 × 4 mm3. Typically, the measurement time is in the range of 1 - 3 s, depending on the number of projected images. Measurements on a 50 µm step standard confirmed that a measurement uncertainty of less than 29.4 ± 3.2 µm is achieved with this system. Mounted on a carrier system, the presented fringe projection system offers the possibility to enter confined areas and perform high-precision 3D measurements.

AB - The 3D measurement of the interior of hollow technical bodies is still a challenge for state-of-the-art measurement systems. This is especially true for complex industrial free-form objects inside confined spaces. Fringe projection enables accurate and fast 3D measurements of object surfaces. To fulfill the task of geometric inspection of confined spaces, we have developed an endoscopic and flexible fringe projection system. The fringe patterns are generated with a RGB LED projector. Fibre-coupling of the structured light is achieved by using a microscope lens and bundle of coherent image fibres. A compact sensor head can be achieved by using a micro-objective for projecting the fringes and a Chip-on-Tip camera to capture the images. A micro lens with a diameter of 1.7 mm was used as the projector lens and a 2 megapixel 1/6” chip was used as the image sensor. By synchronizing the projector with the camera, the system is capable of capturing up to 10 grayscale patterns per second. The measurement volumes result to approximately 20 × 13 × 4 mm3. Typically, the measurement time is in the range of 1 - 3 s, depending on the number of projected images. Measurements on a 50 µm step standard confirmed that a measurement uncertainty of less than 29.4 ± 3.2 µm is achieved with this system. Mounted on a carrier system, the presented fringe projection system offers the possibility to enter confined areas and perform high-precision 3D measurements.

KW - Borescope

KW - Fringe projection

KW - Inspection

KW - Measurement

KW - Optical measurement

KW - Structured light

UR - http://www.scopus.com/inward/record.url?scp=85109361002&partnerID=8YFLogxK

U2 - 10.1117/12.2593019

DO - 10.1117/12.2593019

M3 - Conference contribution

AN - SCOPUS:85109361002

T3 - Proceedings of SPIE - The International Society for Optical Engineering

BT - Optical Measurement Systems for Industrial Inspection XII

A2 - Lehmann, Peter

A2 - Osten, Wolfgang

A2 - Goncalves, Armando Albertazzi

PB - SPIE

T2 - Optical Measurement Systems for Industrial Inspection XII 2021

Y2 - 21 June 2021 through 25 June 2021

ER -