Optical metrology

Optonova has extensive knowledge and experience of optical metrology, the science of measurement using optical methods, above all light in the visible spectrum. This is the dominant technology for non-contact measurement methods, which also include measuring with sound, electrical and magnetic methods and radioactive radiation.

Optical metrology covers numerous areas of knowledge in the measurement technology chain from light source to the finished measurement result. Here are some examples:

Physical optics

For example how light interacts with objects. An accurate physical description of defects and surface properties increases the scope to choose the right methods and geometries. The optical properties of a surface include light scattering, specular reflectance (gloss), polarisation, diffraction, spectral reflectance (colour) and fluorescence. Physical optics are one of the cornerstones of Optonova’s business.

Optical design

Optics and optical methods used include filter techniques, anamorphic optics, telecentric optics and scanning systems. We have software for designing and simulating optical systems.

Photodetectors, image sensors and cameras

We are increasingly using the new smart CMOS cameras in our vision systems. The advantages of the new technology can be summarised as “higher performance at a lower price”, which manifests itself in:

  • Random access to image elements (pixels)
  • High frame rates
  • A/D conversion on chip
  • Smart image sensors with image processing options on chip

Optical measurement geometry and technology

Optonova’s experience includes the following methods:

  • Optical triangulation – methods for measuring distance, position and shape. There are 1D, 2D and 3D methods available.
  • Photometric stereo – a new method for measuring surface topography.
  • Photogrammetry - the traditional method for measuring topography and 3D shape. Automatic 3D sensing is possible using electronic cameras and machine vision.
  • Interferometry – for very accurate measurements of flatness, contours and deviations.
  • Autofocus – initially developed for CD players. Used in metrology for micro-topography measurements.
  • Laser radar – used for scanning systems that measure 3D shapes. Compare with microwave radar.
  • Shadowing and profile projections – laser or vision-based methods for measuring in one or two dimensions.

Lighting technology

I.e. the art of choosing light sources and optics to achieve optimum lighting for an inspection task. Optonova develops complete lighting systems, for example.

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