skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Wavefront error measurement of high-numerical-aperture optics with a Shack-Hartmann sensor and a point source

Abstract

We developed a new, to the best of our knowledge, test method to measure the wavefront error of the high-NA optics that is used to read the information on the high-capacity optical data storage devices. The main components are a pinhole point source and a Shack-Hartmann sensor. A pinhole generates the high-NA reference spherical wave, and a Shack-Hartmann sensor constructs the wavefront error of the target optics. Due to simplicity of the setup, it is easy to use several different wavelengths without significant changes of the optical elements in the test setup. To reduce the systematic errors in the system, a simple calibration method was developed. In this manner, we could measure the wavefront error of the NA 0.9 objective with the repeatability of 0.003{lambda} rms ({lambda}=632.8 nm) and the accuracy of 0.01{lambda} rms.

Authors:
; ;
Publication Date:
OSTI Identifier:
20929650
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Optics; Journal Volume: 46; Journal Issue: 9; Other Information: DOI: 10.1364/AO.46.001411; (c) 2007 Optical Society of America; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ACCURACY; APERTURES; CALIBRATION; CAPACITY; ERRORS; MEMORY DEVICES; OPTICS; POINT SOURCES; REMOTE SENSING; TESTING; WAVELENGTHS

Citation Formats

Lee, Jin-Seok, Yang, Ho-Soon, and Hahn, Jae-Won. Wavefront error measurement of high-numerical-aperture optics with a Shack-Hartmann sensor and a point source. United States: N. p., 2007. Web. doi:10.1364/AO.46.001411.
Lee, Jin-Seok, Yang, Ho-Soon, & Hahn, Jae-Won. Wavefront error measurement of high-numerical-aperture optics with a Shack-Hartmann sensor and a point source. United States. doi:10.1364/AO.46.001411.
Lee, Jin-Seok, Yang, Ho-Soon, and Hahn, Jae-Won. Tue . "Wavefront error measurement of high-numerical-aperture optics with a Shack-Hartmann sensor and a point source". United States. doi:10.1364/AO.46.001411.
@article{osti_20929650,
title = {Wavefront error measurement of high-numerical-aperture optics with a Shack-Hartmann sensor and a point source},
author = {Lee, Jin-Seok and Yang, Ho-Soon and Hahn, Jae-Won},
abstractNote = {We developed a new, to the best of our knowledge, test method to measure the wavefront error of the high-NA optics that is used to read the information on the high-capacity optical data storage devices. The main components are a pinhole point source and a Shack-Hartmann sensor. A pinhole generates the high-NA reference spherical wave, and a Shack-Hartmann sensor constructs the wavefront error of the target optics. Due to simplicity of the setup, it is easy to use several different wavelengths without significant changes of the optical elements in the test setup. To reduce the systematic errors in the system, a simple calibration method was developed. In this manner, we could measure the wavefront error of the NA 0.9 objective with the repeatability of 0.003{lambda} rms ({lambda}=632.8 nm) and the accuracy of 0.01{lambda} rms.},
doi = {10.1364/AO.46.001411},
journal = {Applied Optics},
number = 9,
volume = 46,
place = {United States},
year = {Tue Mar 20 00:00:00 EDT 2007},
month = {Tue Mar 20 00:00:00 EDT 2007}
}
  • A Shack-Hartmann sensor nonintrusive measurement for the temperature profile in a heat-capacity neodymium-doped glass rod is proposed. This technique is possible because the optical path length of the rod changes with temperature linearly over a wide range. The temperature change of the solid-state laser rod is often recorded by using a thermocouple, thermal camera, or phase-shifting interferometer. Based on an analysis of temperature-induced changes in length and index of refraction, we can get the temperature profiles from the wavefront reconstructions in real time. The results suggest the Shack-Hartmann sensors could replace microbolometer-based thermal cameras and phase-shifting interferometers for dynamic temperaturemore » profiles in heat-capacity laser rods with particular advantages. A strange temperature chaos of the Nd:glass rod just after the pump cycle is discovered.« less
  • The wavefront of the radiation of two types from high-power solid-state (Ti:sapphire and Nd:glass) lasers is experimentally studied. The measurements are performed using a Shack - Hartmann wavefront sensor. The technical and functional potential of this sensor in measuring laser-based schemes is demonstrated. The results of measuring both static and dynamic wavefront aberrations are discussed. The estimated dynamics of defocus aberration is in agreement with the experimental data. (measurement of laser radiation parameters)
  • A Shack-Hartmann wavefront sensor (SWHS) splits the incident wavefront into many subsections and transfers the distorted wavefront detection into the centroid measurement. The accuracy of the centroid measurement determines the accuracy of the SWHS. Many methods have been presented to improve the accuracy of the wavefront centroid measurement. However, most of these methods are discussed from the point of view of optics, based on the assumption that the spot intensity of the SHWS has a Gaussian distribution, which is not applicable to the digital SHWS. In this paper, we present a centroid measurement algorithm based on the adaptive thresholding andmore » dynamic windowing method by utilizing image processing techniques for practical application of the digital SHWS in surface profile measurement. The method can detect the centroid of each focal spot precisely and robustly by eliminating the influence of various noises, such as diffraction of the digital SHWS, unevenness and instability of the light source, as well as deviation between the centroid of the focal spot and the center of the detection area. The experimental results demonstrate that the algorithm has better precision, repeatability, and stability compared with other commonly used centroid methods, such as the statistical averaging, thresholding, and windowing algorithms.« less
  • Shack-Hartmann based Adaptive Optics system with a point-source reference normally use a wave-front sensing algorithm that estimates the centroid (center of mass) of the point-source image 'spot' to determine the wave-front slope. The centroiding algorithm suffers for several weaknesses. For a small number of pixels, the algorithm gain is dependent on spot size. The use of many pixels on the detector leads to significant propagation of read noise. Finally, background light or spot halo aberrations can skew results. In this paper an alternative algorithm that suffers from none of these problems is proposed: correlation of the spot with a idealmore » reference spot. The correlation method is derived and a theoretical analysis evaluates its performance in comparison with centroiding. Both simulation and data from real AO systems are used to illustrate the results. The correlation algorithm is more robust than centroiding, but requires more computation.« less
  • The analytic frequency responses of the traditional wavefront reconstructors of Hudgin, Fried, and Southwell are presented, which exhibit amplification or attenuation of the original signal at high spatial frequencies. To overcome this problem, a reconstructor with unity frequency response is developed based on a band-limited derivative calculation. The algorithm is both numerically and experimentally confirmed.