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Machine Vision Applications of Line Scan Cameras

Line Scan Camera Applications

Generally, the applications can be grouped into one-dimensional or two-dimensional measuring tasks. For one-dimensional applications, the measured result is extracted from the pixel information of an individual line scan. Measurements of two-dimensional images require moving either the object or the line sensor

Camera Application:

1-dimensional

  • Signal generation: individual line scan
  • Examples: measurement of width, rod diameter, edge positions, glass thickness.

2-dimensional

  • Several line scans are combined to produce a 2D image (frame)
  • Examples: surface inspection, endless webbing inspection, texture analysis, scanning

Applications of Linear Scanner Systems

Using the standard components of translation stage, illumination unit and line scan camera, Schäfter+Kirchhoff have developed scanner systems for the fast and objective measurement of objects of interest consisting of various materials.One example is the Corrosion Inspector for evaluating filiform and other corrosion phenomena on coated test plates.A standardized test plate of 200 mm length is scanned in 0.8 seconds. The resolution is 40 microns/pixel for the monochrome system and 22 microns/pixel for color.

  • High speed translation stage with high positional accuracy.
  • Coaxial LED line light, adjustable angle for bright or dark-field illumination
  • Powerful application software for visualizing and measuring objects consisting of various materials.

Sample Application: Evaluation of Corrosion

More details can be found on the individual pages of the Corrosion Inspector and Robot-guided Corrosion Inspector.

Filament counting

Ranking of filament lengths
Evaluation according to GSB: H= Z / L, F= l*H

Delamination and Corrosion

  • Evaluation according to ISO 4628-8
  • Using true color analysis for red rust detection
  • Total corrosion area minus scribe line (mm²), marked red
  • Separation of delamination area (mm²), marked green

Software Functions SKan-CI

The software SKan-CI is used to analy the corrosion and provides the following:
  • Control of camera, lighting and motor stage
  • Variable scan lengths, measuring in ROI
  • Image processing, contrast enhancement, zoom.
  • Filiform and red rust detection and evaluation
  • Exports: original image, binary result image (png),
  • Data export to ExcelTM, LibreOffice Calc

Sample Application: Measurement of Dimension

Using the linear scanner system from Schäfter+Kirchhoff, the measurement of distances, dimensions and positions of objects is possible.
  • Ø1 - Ø4: measurement of diameters of holes
  • d12 - d34: measurement of distances between the hole

Applications using High-End Imaging and Illumination Optics

  • High resolution scan lenses
  • High resolution telecentric lenses
  • Coaxial directed LED light for bright or dark-field illumination

Resolution: down to 5 μm/pixel (5080 dpi)

Options:

  • Telecentric lens
  •  Direct linear drive
  • Operating temperature down to -30 °C

Sample Application: Ice Core Research

More details can be found on the individual pages for the Large Area Scan Macroscope LASM as well as the Intermediate Layer Core Scanner ILCS. An article on microstructure mapping can be found here.

Scan of an ice core from a depth of 60 m under Antarctica. The light granular structure and dark gas bubbles are clearly discernable.

Scan of an ice core from 1035 m deep.The bubbles have been almost completely transformed into gas hydrates.

Telecentric imaging

An article on telecentric imaging can be found here.

Advantages of a telecentric beam path in distinction from common endocentric imaging

A telecentric lens views all points of the object directly from above. The resultant image is similar to a 2D technical drawing of the object. If variations in object height extend beyond the depth of focus then the image may be locally blurred but the object size remains constant.This makes it possible to determine the width of an indentation without interference by the vertical sidewalls. [more]

Sample Application: Stent Research

Surface quality and dimensions are detected using a telecentric lens and a line scan camera with integrated bright-field illu mination. During stent rotation, the line scan camera rapidly records a planar 2D image of the un wound mesh structure. [more]

Applications using a linear Color Scanner

The variety of color line scan cameras allows the assembling of color scanners for surface inspection of planar objects in a wide range of scan widths and resolutions. Typical applications are the inspection of wood surface, scanning of books and documents, or quality control of printings.The customers requirements decide about the used components of camera, lens, illumination unit, and the linear motor axis. For example, a wood plate of 20 mm width can be scanned with a resolution of 20 microns per pixel, or 1270 dpi.

Sample Application: Wood Surface Inspection

Artwork masters for interior decoration (laminate or tilework floor)

Applications using a rotating color scanner

When scanning cylindrical objects, the line scan camera has a substantial advantage over other imaging methods using a matrix camera, for example. When focused on the zenith of the round object, the line scan camera delivers sharp, distortion-free images of the lateral surface as the cylinder is rotated.Schäfter+Kirchhoff has capitalized on this line scan advantage to develop the Core Plug Scanner. Geological exploration for oil, gas, ores or minerals does generate a large number of drill core plugs for assessment. The lateral surfaces of the cores require visualization in high quality with the subsequent storage of lossless data in digital form. A color line scan camera with 3x 2096 pixels is used to generate the images. Prior color calibration of an IT8-target guarantees the capturing of the core plug surface in true color. The USB 3.0 interface of the camera allows the scanner to be controlled with a notebook and predestines the system for mobile use. The device is also delivered in a sturdy aluminium case for this purpose.The roller drive facilitates the rapid and easy loading of the drill core samples.

Sample Application: Core Plug Scanner

Imaging of a mineral core, scanned using the Core Plug Scanner from Schäfter+Kirchhoff.