| Test Configuration Overview |
|
SpotOptics wavefront sensors and wavefront sensor based systems based on Shack-Hartmann principle are simple to use. The Shack-Hartmann test is simple to perform: First, we use the wavefront sensor based on Shack-Hartmann principle with Sensoft to capture the Shack-Hartmann frame of the optical element under test. Next, the wavefront sensor with Sensoft captures the reference Shack-Hartmann frame, using an internal calibration source. Sensoft, the software which has acquired the Shack-Hartmann frames analyzes the
wavefront, on-line or off-line and provides the results immediately.
All our wavefront sensor based instruments come complete with the calibration source.
Choose from the following list the element you would like to test
|
|
|
| Lenses |
|
| Single lens |
|
| Shack-Hartmann wavefront sensors test of single lens |
|
 |
|
Setup:
In this configuration, aberration free parallel light falls on the lens L being tested, and comes to a focus before being fed to the Shack-Hartmann wavefront sensor Puntino.
The aberrations of the SH system itself are removed taking a calibration frame, with an in-built calibration source placed at the focus of Puntino. The calibration source is controlled from the PC.
It is not necessary to use parallel light for the test. The measured aberrations will then no longer refer to those for parallel light, but to one particular optical configuration that is used for the test.
|
|
|
|
|
|
|
| Multiple lens system |
|
| Shack-Hartmann wavefront sensors test of a multiple-component lens |
|
 |
|
Setup:
In this configuration, aberration free parallel light falls on a multiple-lens system L being tested, and comes to a focus before being fed to the Shack-Hartmann wavefront sensor Puntino. The aberrations of the Shack-Hartmann system itself are removed taking a calibration frame, with an in-built calibration source placed at the focus of Puntino. The calibration source is controlled from the PC.
It is not necessary to use parallel light for the test. The measured aberrations will then no longer refer to those for parallel light, but to one particular optical configuration that is used for the test.
|
|
|
|
|
|
|
| Single lens with flat mirror |
|
| Shack-Hartmann wavefront sensors test of single lens |
 |
|
Setup:
In the above configuration, diverging light from Optino wavefront sensor based on Shack-Hartmann principle falls on the lens L under test. It is made parallel by it, and falls on a flat mirror M (which should be of a high quality, say λ/4, λ/10 or λ/20, depending on the accuracy required for testing the lens L). The light from the mirror M returns to Optino, wavefront sensor based on Shack-Hartmann principle, and passed to the SH system.
The aberrations of the Shack-Hartmann system itself are removed taking a calibration frame of a small high quality (like for the flat mirror above) spherical mirror instead of the lens L.
The mirror should have a minimum diameter equal to that of the lens L, and the focal ratio of the lens C2 should match that of the lens L.
|
|
|
|
|
|
|
| Multiple lens system with flat mirror |
|
| Shack-Hartmann wavefront sensors test of Multi-component lens |
 |
|
Setup :
In the above configuration, diverging light from Optino wavefront sensor based on Shack-Hartmann principle falls on the lens L under test. It is made parallel by it, and falls on a flat mirror M (which should be of a high quality, say l /4, l /10 or l /20, depending on the accuracy required for testing the lens L). The light from the mirror M returns to Optino, and passed to the Shack-Hartmann system.
The aberrations of the Shack-Hartmann system itself are removed taking a calibration frame of a small high quality (like for the flat mirror above) spherical mirror instead of the lens L.
|
|
|
|
|
|
| Single lens with spherical mirror |
|
| Shack-Hartmann wavefront sensor test of single lens |
 |
|
Setup:
In the above configuration, parallel light is falls on the lens L being tested, and comes to focus at F. It is then reflected back into the system by the spherical mirror S.
The aberrations of the Shack-Hartmann system are removed by taking a calibration CCD frame with a good quality flat mirror in parallel light, before it falls on the lens L.
This setup is evidently limited to testing small lenses, the limitation being imposed by the beam-size that the CCD can accept.
The accuracy of the tests depends on the quality of the spherical mirror S and the flat mirror used for the calibration.
|
|
|
| Multiple lens system with spherical mirror |
|
| Shack-Hartmann wavefront sensor test of multi-component lens |
 |
|
Setup:
In the above configuration, parallel light from Optino wavefront sensor based on the Shack-Hartmann principle falls on the element L being tested, and comes to focus at F. It is then reflected back into Optino wavefront sensor by the spherical mirror S.
The aberrations of the Shack-Hartmann system are removed by taking a calibration CCD frame by using a good quality flat mirror in the parallel light, before it falls on the lens L.
This setup is evidently limited to testing small lenses, the limitation being imposed by the beam-size that the CCD can accept.
The accuracy of the tests depends on the quality of the spherical mirror S and the flat mirror used for the calibration.
|
|
|
|
|
|
| Mirrors |
|
| Spherical mirror |
|
| Shack-Hartmann wavefront sensors test of multi-component lens with a flat mirror internal illumination |
 |
|
Setup:
In the above configuration, light from Optino, wavefront sensor, it comes to a focus at F (which is also the radius of curvature of the spherical mirror). It falls on the spherical mirror, and retraces its path, passing though Optino wavefront sensor again, going through the Shack-Hartmann system.
The aberrations of the SH system itself are removed taking a calibration frame of a small high quality spherical mirror instead of the lens L. This determines the accuracy of the test.
The spherical aberration of a mirror at its center of curvature is given by:
Here ASA is the angular spherical aberration (diameter of image at best focus – in radians), K the conic coefficient of the mirror, r the ray height on the mirror, and R the radius of curvature. Spherical mirrors have zero ASA (K =0), while parabolic (K =-1) and hyperbolic (K <-1) mirrors have large positive spherical aberration. However, Sensoft is capable of testing mirrors with hundreds of wavelengths of aberrations.
|
|
|
| Flat mirror |
|
| Shack-Hartmann wavefront sensor test of a flat mirror |
 |
|
Setup:
The Ritchey-Common configuration is used for testing a flat mirror, in conjunction with a spherical.
First the Shack-Hartmann frame of the spherical mirror is obtained directly: this becomes the calibration frame. Then the Shack-Hartmann frame of the flat + spherical mirror is obtained, using the configuration shown above. Then the analysis proceeds in the usual way, thus giving the optical quality of the flat mirror alone.
Clearly, since the aberrations of the spherical mirror are removed by the calibration process, it does not need to be of a very high quality.
In the above configuration, the spherical mirror has been placed at an angle of 90 degrees. Other angles can be also used.
|
|
|
|
|
|
| Ophthalmic lenses |
|
| Ophthalmic lenses |
|
| Test of an ophthalmic lens with Optino wavefront sensors |
|
|
An ophthalmic lens was tested using Optino wavefront sensor based on Shack-Hartmann principle and SensoftOptino, the wavefront sensor control and analysis software of Optino.
See how sensitive is our system to detect the effect of a jaw clamp support on the ophthalmic lens.
|
|
|
Lens with a metal ring around mounted in a jaw clamp: no distortion is seen.
|
|
|
|
|
Lens with no metal ring around it held in a jaw clamp: presence of triangular coma is seen.
|
|
|
|
Information given by Optino and SensoftOptino.
Optino gives you the all the information you would expect from a wavefront analyzer:
- the aberrations in terms of Zernike coefficients (more than 50 polynomial terms and 4 different sets of polynomials can be fit to the data).
- Strehl ratio, P-V, EE, MTF, PSF, wavefront, spot diagram and more...
With a simple modification of the light source and/or the use of our optional Beam-expander unit, optical elements of practically any diameter and nature (diverging or converging) can be tested from f/0.5 to f/500.
See section on
See section on configurations for the various test setup.
We supply standard solutions, but can also work on custom solutions, if you have any special needs.
|
|
|
|
|
|
| Human eye |
|
| Human eye |
|
| Shack-Hartmann analysis of the human eye |
 |
|
|
The map of the wavefront of the human eye as found by our Shack-Hartmann software package Sensoft, only for astigmatism. The coefficient as computed from Sensoft had an angle of -10 degrees, which is consistent with the angle from the figures (the angle of the peak, or the red area). These are just the initial results. More results will follow soon.
|
|
|
|
|
|
| Astronomical telescopes |
|
| Telescope at
Cassegrain focus |
|
| Shack-Hartmann wavefront sensors test of a telescope at Cassegrain focus |
|
|
Setup:
A telescope tested at the Cassegrain focus using external parallel light. The aberrations of the Shack-Hartmann system itself are removed by taking a calibration frame, with a calibration source placed at the focus of Puntino. Puntino wavefront sensor based on the Shack-Hartmann principle. The incident light illuminating the system should be aberration free. In the case of an astronomical telescope, a natural star is used.
It is not necessary to use parallel light for the test. The measured aberrations will then no longer refer to those for parallel light, but to one particular optical configuration that is used for the test.
|
|
|
|
|
|
| Telescope at Newtonian/Prime focus |
|
| Shack-Hartmann wavefront sensor test of a telescope at Newtonian focus |
|
|
Setup :
A telescope tested at the Newtonian focus using parallel light. The aberrations of the Shack-Hartmann system itself are removed by taking a calibration frame, with a calibration source placed at the focus of Puntino. wavefront sensor based on Shack-Hartmann principle. The incident light illuminating the system should be aberration free. In the case of an astronomical telescope, a natural star is used.
It is not necessary to use parallel light for the test. The measured aberrations will then no longer refer to those for parallel light, but to one particular optical configuration that is used for the test.
|
|
|
|
|
|
|
 overview |
|
| Lenses |
|
|
|
|
|
|
|
| Mirrors |
|
|
|
| Opthalmic lenses |
|
|
| Human eye |
|
|
| Astronomical Telescopes |
|
|
|
