Wider View

Combining Multiple Contact Image Sensors for Line Scanning

Mitsubishi Electric and Euresys have cooperated to push the limits of the inspection of large object surfaces by contact image sensors (CIS). Two sensors inspect wider surfaces. Each sensor is connected to two Euresys Grablink Full XR frame grabbers. The four frame grabbers are able to stitch the images together, while managing the overlap, in order to produce a single image.

Bild: Euresys SABild: Euresys SA
Image 1| In recent application cases, Mitsubishi Electric and Euresys have cooperated to push the limits of the inspection of large object surfaces. A recent case involves the simultaneous use of two Camera Link CIS, the goal being to inspect wider surfac

Inspection using line-scan sensors is somewhat a niche market within the machine vision market. Line-scan sensors are used when a very high-resolution image is required to inspect the surface of large, moving, flat objects such as paper, laminates, plastic films, textile, foils, glass, steel or PCBs. Building inspection systems using line-scan sensors requires a unique know-how as, contrary to area-scan acquisition, a tight coupling of the sensor acquisition rate (i.e., the line rate) and the object's movement is required. "Contact Image Sensors (CIS) such as offered by Mitsubishi Electric have clear advantages against more traditional line-scan cameras" says Marc Damhaut. They are placed very close to the object to be inspected and are a perfect solution when there is little space available around the object. They offer a telecentric view of the surface to be inspected, with no distortion and no lighting non-uniformities. Hence, they produce a 1:1 image which is an accurate representation of the surface. In addition, CIS are complete solutions that integrate the sensor, its lighting and optics into a single device that can be offered pre-calibrated. This results in a genuine and undistorted image.

Euresys has a lot of experience with line-scan applications. Their Camera Link and CoaXPress frame grabbers offer all the functions required to control line-scan sensors, including CIS. The frame grabbers feature general-purpose I/O lines dedicated to interfacing quadrature motion encoders, with various types of electrical interfaces and programmable noise filters. In addition, features such as the Rate Divider and the Rate Converter tools available in the frame grabbers allow the fine control of the synchronization between the object's motion and the sensor's line rate, and thus the pixel aspect ratio.

Euresys SA

Dieser Artikel erschien in inVISION E-Magazin Kameras & Komponenten 2023 - 17.05.23.
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