What constitutes the "quality" of optics? This term unites a comprehensive package of optic but also mechanic properties which, depending on the application case, are of special interest. Eventually one must always make a compromise between price/performance and optic quality.
- high transmission (and low stray light)
- high image contrasts when depicting the objects
- high resolution
- low vignetting, i.e. uniform image brightness
- low geometric distortion
- low optical imaging errors like spherical or chromatic aberration, coma and astigmatism
- mechanic precision and ruggedness against vibrations
- set screws, filter thread, etc.
Application cases vs. optic quality
High-quality optics must always be adapted to the camera with its image sensor and the intended use. Measuring applications, colour checks, inspections in IR light, robot applications or simple presence checks make different optic quality requirements.
- Measuring applications often require a high resolution and low geometric distortion.
- Camera systems in combination with robots should also have low geometric errors, a robust design and should, if necessary, be very compact and lightweight if they are mounted to the handling system.
- In case of colour inspections it may possibly be especially important that the optics have few colour errors (low chromatic aberration) which result in colour fringes with colour errors on the edges and in blurred images.
- Applications in the IR and UV range of light also require special lenses which are designed for and adapted to these wavelengths. The coating and spectral transmission of the glasses is of special interest here.