We have measured the wavefront aberrations of fused silica and silicon microlenses using a Shack-Hartmann wavefront sensor system. The Shack-Hartmann sensor uses a combination of a microlens array and a CCD camera to measure wavefront local tilts with respect to a reference wavefront. Data reduction software then reconstructs the wavefront and expresses it in various forms such as Seidel or Zernike. We measured a series of our custom microlens arrays by placing a fiber source at a distance of one focal length behind the array to create a series of collimated beams from the individual lenslets. We then observed the quality of the collimated beams from single lenslets by using different aperture converters (for different sized lenslets) to expand the individual beams so that they filled a significant portion of the CCD area. For these microlens arrays, the P-V OPD was found to be less than λ/4 and the RMS wavefront error less than λ/20.
We are investigating the use of a Shack-Hartmann wavefront sensor for measuring optical component quality during manufacture and testing. In a variety of fields, an optical component is designed to pass an optical signal with minimal distortion. Quality control during the manufacturing and production process is a significant concern. Changes in beam parameters, such as RMS wavefront deviation, or the beam quality parameter M<SUP>2</SUP>, have been considered as indications of optical component quality. These characteristics can often be quickly determined using relatively simple algorithms and system layouts. A laboratory system has been prepared to investigate the use of a wavefront sensor to measure the quality of an optical component. The instrument provides a simultaneous measure of changes in M<SUP>2</SUP> and induced RMS wavefront error. The results of the investigation are presented.
Scanning mirrors for micro-display systems typically require operation at frequencies over 15 kHz. These mirrors undergo large dynamic stresses and inertia related deformations. We report here on the measurement of these dynamic deformations using a commercially available Shack-Hartmann wavefront sensor with data reduction software. The measured deformations using the Shack-Hartmann wavefront sensor are shown to agree with measurements obtained using a stroboscopic interferometer. Advantages of the Shack- Hartmann wavefront sensor are discussed.