Aspheres

Aspheres offer the great advantage to accomplish imaging tasks with one optical element where lens systems were needed otherwise.

 

Main advantages of aspheres are:

 

  • less spherical aberrations
  • less weight
  • increased transmission
  • no internal ghosts

 

The combination of high purity fused silica and low absorption coatings decreases the thermal induced shift of focal length and working distance.

 

Another application of an asphere is beam shaping with respect to the intensity distribution or the phase. A typical conversion is the change of a Gaussian profile into a top-hat profile. For material processing, this form has the advantage of a more homogeneous removal of surface material, steeper borders between removal zone and surrounding material and a resulting smaller heat affected zone (HAZ).

 

The capability of Sill Optics MRF machines allows production of aspheres up to diameter 200 mm. Measurement setup (interferometric wavefront test, tactile and optical 3D profi lometry) enables us to
ensure a surface quality of 0.15 μm PV(fWD) and RMSi < 0.025 μm depending on geometry. Even sagittal heights z(r) up to 21 mm are measurable enabling the production and test of very steep radii at certain diameters.

 

Our range of products covers unmounted and mounted precision aspheres out of fused silica with focal lengths from 20 mm to 400 mm, which are usable for focusing and collimation.

 

Special forms and customized versions are available on request.  Our technological possibilites are listed below. Further information (e.g. design guidelines for apsheres) can be found in our Technicon.