Testing lenses with Optino: measure stress due to lens mounting

SpotOptics Shack-Hartmann wavefront sensor Optino and  Sensoft software were used to test an ophthalmic lens held in a 3-point clamp.

Output results from Sensoft analysis are the table with the Zernike coefficients  (at left in the figure below) and several graphs.

An important feature in Sensoft is the wavefront map reconstruction. This means that the user can select and see in the map the effect of any aberration(s).

  • In the example given above (see figure above, wavefront at left), Defocus, Tilt and Astigmatism were mathematically removed in the map. The typical 3-point structure of Triangular Coma (213 nm) is quite evident in the wavefront . The conclusion is that the 3-point clamp generates stress in the lens. The relevant amount of Astigmatism and Triangular Coma is the consequence of this.
  • When removing the 3-point clamp Astigmatism is much smaller and Triangular Coma is negligible (see figure below).

 

Test of the same lens after removing the 3-point clamp

By removing the 3-point clamp, Astigmatism decreases from 875nm to 93nm and Triangular Coma from 213nm to 8.5nm. Compare the new wavefront (with Defocus, Tilt and Astigmatism mathematically removed) with the graphs above.

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