In the world of modern imaging technologies, spectral imaging opens up completely new possibilities for identifying and analyzing a wide variety of materials. Thanks to customized optics and illumination for hyper- and multispectral imaging, specific properties and structures of materials can be made visible that would not be visible to the naked eye or with conventional imaging techniques.
Hyper- and multispectral imaging uses light in specific wavelength ranges to obtain detailed information about the chemical composition and physical structure of materials. This is because each material has a unique reflectance intensity in the spectrum that can be used for identification. This property is crucial for applications such as quality assurance in industry, medical imaging or environmental monitoring.
Optical requirements for spectral imaging
Special requirements for the optics are necessary for optimum spectral imaging:
- Minimal adjustment of the working distance (WD): lateral chromatic aberration should be kept to a minimum to ensure sharp and accurate images.
- Chromatic correction/optimization: The optics must be matched to the specific spectral range of the application. Specialized characteristics are more important here than broadband coverage.
- Uniform light transmission: The light transmission of the lens must not decrease too much, especially at wavelengths above 1400 nm.
- Specific adjustments: These include primary magnification (PMAG), working distance (WD), space limitations and depth of field (DoF). These requirements apply to telecentric as well as entocentric and epicentric lenses.
Optical solutions: APOchromatic correction
A key aspect of the optical solutions is apochromatic correction. The chromatic dispersion caused by different focal lengths at different wavelengths is corrected by systematically combining different types of glass. An example of this is the combination of short flint (KzF) glass. The Abbe number (ν) is a measure of this dispersion, whereby Δf (lateral chromatic aberration) is inversely proportional to the Abbe number. Developments in apochromatic correction and innovative lighting technology are helping to ensure that this technology continues to advance and open up new possibilities in a wide range of applications.
TO66/11.0-120-V-VSWIR for 2/3-inch sensors
For the vicotar® BLUE Vision lens TO66/11, apochromatic correction was used to optimize the optics for the VIS to SWIR range. The “Focal Shift over Wavelength” diagram shows the results of this correction.
The low adjustment of the working distance (WD) and the diffraction MTF at aperture F14 underline the high precision of these optics.
Vision & Control's bi-telecentric objectives, originally designed for VIS+NIR, are versatile and offer outstanding performance in the SWIR range.
The combination of innovative technology and precise adaptation to the respective requirements makes Vision & Control a leading supplier in this pioneering field.