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Applications

Quality Control

Scan macroscope for the quality control of medical implants

In Germany several 100,000 stents (for the prevention of disabilities in blood flow) are implanted every year. Contrary to popular opinion, however, stents are used not only for elderly but for people of all ages, from small children to old age.

The tubular stent is constructed of a mesh structure. With the quality control the geometry of the stent, the ridge width and the surface texture are reviewed in order to ensure an immaculate product. Schäfter+Kirchhoff has developed a scan macroscope, which for this purpose produces high-resolution 2D images of stents

Large Area Scan Macroscope

For automated grid finger inspection.

Improvements in solar cell efficiency are an important part of the effort to develop a sustainable energy supply in the modern world. Each processing step is monitored during production to ensure the highest quality. An important performance feature is the regularity of the grid fingers and the bus bars (the conductor strips collecting the charge carriers). Defects such as gaps and tapers reduce the efficiency and must be avoided. The Schäfter+Kirchhoff large area scan macroscope provides a 100%-level of quality control.

Components

  • Line Scan Camera SK7500GTO-XL
  • Scan Lens Apo-Rodagon-N4.0/80
  • Software SK91GigE-WIN
  • Illumination:
    2 × Excimer lamps LINEX-A4-10W24
    2 × HF inverters LINEX-RT-1x24/24

Quality Control

Corrosion Inspector

Measurement and evaluation of corrosion phenomena on coated test plates

  • Filiform - Evaluation according ISO 21227-4
  • Delamination and Corrosion - Evaluation according to ISO 4628-8
  • Corrosion sites - evaluation of multi-impact acc. ISO 20567-1
    - degree of blistering acc. ISO 4628-2
  • Test plate size max. 100 mm x 200 mm
  • Scan velocity 250 mm/s
  • Resolution 0.04 mm

Further information

Dark-field illumination for Wafer inspection

In industrial image processing, dark-field illumination is particularly useful for the examination of highly reflecting surfaces. The light beam is directed at the surface of the test object at a low angle of incidence,so that the light is undetected by the camera when reflected from a perfect surface. With an immaculate surface, therefore, a scanned object appears completely dark.

When there are surface irregularities caused by some damage, such as a scratch or a crack, or contamination,such as dust, lint or grease, then a small part of the incident light is scattered diffusely, captured by the lens and directed onto the sensor.

Tiny irregularities can be detected that are even under the resolution limit of the lens. The image may not always be completely in focus anymore, just like viewing a star in the night sky, but the increase in reflected light at the sensor is still detectable.

Application fields

  • Surface examination of highly reflective materials, e.g. chips, wafers or mirrored surfaces.
  • Highlighting of contours, scratches, cracks, dust particles and dirt.

O-Ring Groove Surface Analysis: Inspection of sealing areas

Inspections system with three CCD line scan cameras - endocentric and Scheimpflug optical configuration

The imaging system developed by Schäfter+Kirchhoff for inspecting the base and sides of a machined groove, for the acceptance of an O-ring, uses three CCD line scan cameras, SK512ZPD. Two cameras are positioned to utilize the Scheimpflug principle for monitoring the internal sides of the groove. A third camera monitors the base of the groove and its surrounding surface details.

This particular configuration allows complicated surface features to be resolved at signal intensities with 60-times higher amplitude and at 3-times better resolution, when compared with a conventional system.

Line Scan Camera SK8160GKO-XL with Telecentric Lens

Line Scan Camera SK8160GKO-XL with telecentric lens and integrated brightfield illumination

A standard camera lens as well as the human eye provide an endocentric perspective. An object appears to be larger when viewed from close up and smaller when it is further away. This means that when an object with vertical indentations is viewed from above then not only the indentation but also a portion of the vertical sidewalls can be seen, as well. This confuses the precise determination of an object width, a cavity size, or a ridge width in machine vision and severely compromises the measurement results. The solution to this problem is to use a lens with a telecentric perspective.

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.

Variations in object distance may still result in localized blurring of the image (especially if these extend beyond the depth of focus) but the apparent object size remains constant. It is now possible to determine the width of the indentation without any distraction from the vertical sidewalls.

In telecentric imagery, the front lens must be larger than the size of the object. This is a challenging requirement with larger objects, especially if a high optical resolution is needed. The present system maintains a resolution of 10 μm/pixel (2540 DPI) over a field of view of more than 80 mm. Sub-pixel algorithms can push down the measurement accuracies even further, to only a few microns.

Line Scan Cameras

Bore Plug Inspection: High Resolution Color Scanner for Cilindric Objects

The bore plug scanner SK-4080-GigE Color is a fully mobile surface-scanning macroscope that was specially developed by Schäfter+Kirchhoff for the investigation of smooth and cylindrical objects, such as bore plugs.

Features

  • Rapid and precise exchange of test objects by using two rotating supports
  • Simple adjustment of focus for objects with different diameters
  • A surface scan by simply pressing a switch or a mouse button
  • Automatic white balance
  • One-click zooming for 1:1 depictions
  • Printing and saving of complete or zoomed sections
  • USB 2.0 interface makes the positioning of the scanner highly flexible so that it can be used almost anywhere

Polar Ice Cores: Large Area Scan Macroscope (LASM)

Innovative development in glaciology for the investigation of the microstructure of polar ice cores

The large area scan macroscope from Schäfter+Kirchhoff was developed for the Alfred Wegener Institute for Polar and Maritime Research in Bremerhaven for use at temperatures down to -30°C (and ultimately -60°C).

This ice scanner is a vast improvement over traditional methods in terms of quality, reproducibility and speed.

Large Measuring Span: Stratigraphy Scanner using Dark-Field Illumination

Innovative developments in glaciology for the inspection of polar ice core laminar structure at 50 µm resolution across a measured span of 105 mm and scan length of over 1 m.

The ILCS Scanner was developed by Schäfter+Kirchhoff for expeditions into the polar regions and all of the mechanical, electronic and optical components were designed for use at temperatures down to -40°C.

The ILCS Scanner is used to image the  laminar structure of up to 1.7 m long ice core sections.

Geometry Evaluation with Laser Diffraction

One of the most popular applications in laser measurement is the evaluation of the shadow thrown by an illuminated object.

A line sensor is set up to receive a collimated laser beam so that an object crossing the beam produces a shadow. The overlapping shadows are captured on the line sensor as Fresnel interference patterns.

For measurements of diameters, geometries and edge detection with high precision and speed.

  • Evaluation of shadow edges
  • Evaluation of Fresnel diffraction patterns

Line scan cameras with integrated bright field illumination

High-contrast image acquisition of structured objects; making the invisible visible. Illumination and image acquisition techniques that are well adapted to the object properties emphasize the object features of interest. Elaborate image processing algorithms are avoided.

Line scan sensor heads by Schäfter+Kirchhoff combine the line scan camera, the measuring object and a LED-based directed bright field illumination in a ruggedized unit, highly suited for industrial applications. The LED illumination is aligned with the camera lens and has a long service life of several years.

Quantum Optics

Fiber Port Clusters for Magneto Optical Trap (MOT)

Fiber-coupled beam delivery system, postcard size, replaces 1 m² breadboard constructions

The cooling of an atomic cloud down to a very few micro-Kelvin in an atomic trap brings thermal motion to a virtual standstill. To reach micro-Kelvin temperatures, a magneto-optical trap produced from magnetic fields and laser radiation is used.

A magneto-optical trap (MOT) is often used for the initial cooling phase before other super-cooling mechanisms bring the temperature down for Bose-Einstein condensation.

Experimental reproducibility when using cold atoms requires an extremely stable setup. This is achieved most effectively by using polarization-maintaining fiber optics to mechanically decouple the vibration and temperature sensitive optics from the trap.

Laser

Measuring and Process Control in 3D using Laser Lines, Laser Spots and Laser Patterns

Laser light sectioning is a 3D method for determining a profile at a predefined incident section using laser triangulation. The imaging camera is mounted directly perpendicular to the scanned object and it measures the lateral displacement and distortion of the incident laser line projected at an angle a onto the object.

The recorded camera image contains all of the height information obtained from the section defined by the incident laser beam, which is then decoded to provide the 3D height profile as the object passes through the laser line camera detection system.

Further information…

Precision Grid Projektor SK 5732

Structured Illumination for 3D Measurements

Multi-line light-sectioning is a technique to measure small height differences in structured objects by using a grid projected onto the object surface at a low angle. A matrix camera perpendicular to the object is used to record the image of the projected grid lines.

A structured object distorts or displaces the grid image and this is recorded by the camera for evaluation of the line displacement and calculation of the object height, contour or profile.

Further information…

Schäfter + Kirchhoff GmbH - specialists for optical sensors and measurement technology
Kieler Str. 212, D-22525 Hamburg, Germany, Tel. +49(0)40 85 39 97-0, Fax +49(0)40 85 39 97-79
E-Mail info~at~SuKHamburg.de