Tolerance analysis of misalignment in an optical system using Shack–Hartmann wavefront sensor: experimental study
01 Jul 2015-Optical Engineering (International Society for Optics and Photonics)-Vol. 54, Iss: 7, pp 075104-075104
TL;DR: In this article, the wavefront aberrations induced by misalignments due to decentration and tilt of an optical component in an optical measurement system are presented and the results are compared with experimental values.
Abstract: The wavefront aberrations induced by misalignments due to decentration and tilt of an optical component in an optical measurement system are presented. A Shack–Hartmann wavefront sensor is used to measure various aberrations caused due to the shifting of the axis and tilt of a lens in the path of an optical wavefront. One of the lenses in an optical system is decentered in the transverse direction and is tilted by using a rotational stage. For each step, wavefront data have been taken and data were analyzed up to the fourth order consisting of 14 Zernike terms along with peak-to-valley and root mean square values. Theoretical simulations using ray tracing have been carried out and compared with experimental values. The results are presented along with the discussion on tolerance limits for both decentration and tilt.
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01 Sep 2002
TL;DR: An OSA taskforce was formed at the 1999 topical meeting on vision science and its applications and charged with developing consensus recommendations on definitions, conventions, and standards for reporting of optical aberrations of human eyes.
Abstract: In response to a perceived need in the vision community, an OSA taskforce was formed at the 1999 topical meeting on vision science and its applications (VSIA-99) and charged with developing consensus recommendations on definitions, conventions, and standards for reporting of optical aberrations of human eyes. Progress reports were presented at the 1999 OSA annual meeting and at VSIA-2000 by the chairs of three taskforce subcommittees on (1) reference axes, (2) describing functions, and (3) model eyes.
85 citations
TL;DR: This paper uses a hybrid optical simulation model that comprises virtual and identified component positions that enables prediction of the future wavefront at the detector plane and therefore allows for taking corrective measures accordingly during the assembly process if a user-defined tolerance on the wavefront error is violated.
Abstract: Alignment of optical components is crucial for the assembly of optical systems to ensure their full functionality. In this paper we present a novel predictor-corrector framework for the sequential assembly of serial optical systems. Therein, we use a hybrid optical simulation model that comprises virtual and identified component positions. The hybrid model is constantly adapted throughout the assembly process with the help of nonlinear identification techniques and wavefront measurements. This enables prediction of the future wavefront at the detector plane and therefore allows for taking corrective measures accordingly during the assembly process if a user-defined tolerance on the wavefront error is violated. We present a novel notation for the so-called hybrid model and outline the work flow of the presented predictor-corrector framework. A beam expander is assembled as demonstrator for experimental verification of the framework. The optical setup consists of a laser, two bi-convex spherical lenses each mounted to a five degree-of-freedom stage to misalign and correct components, and a Shack-Hartmann sensor for wavefront measurements.
10 citations
TL;DR: The proposed sensitivity optimization method can homogenize image performance for the same field under different tolerance values and improves the product yield rate by 15 to 17% compared with a traditional optimization method.
Abstract: During the production of a lens system, the assembling and manufacturing tolerances must be accurately controlled to ensure production efficiency. Thus, it is important to analyze and optimize the tolerance sensitivity of the lens system during the optical design phase to reduce optical performance degradation. We proposed an approach for appropriately controlling the tolerance sensitivity of a lens system. The proposed sensitivity optimization method can homogenize image performance for the same field under different tolerance values. Based on the results, we show that the implementation of the proposed method sharply reduces sensitivity and, consequently, improves the product yield rate by 15 to 17% compared with a traditional optimization method. As a practical example, a 40-megapixel f1.8 mobile phone camera lens design and optimization process was performed in our study. Our preliminary experimental results confirm that the proposed method is effective to reduce the optical sensitivity of the camera lens.
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TL;DR: In this paper, the authors measured the refractive errors of normal, healthy eyes using an indigenously developed Shack-Hartmann aberrometer, which was used to represent the sphero-cylindrical errors.
Abstract: The refractive errors of normal, healthy eyes were measured using an indigenously developed Shack–Hartmann aberrometer. Measurement was made in both right and left eyes after dilation for a 6 mm pupil size. The power vector method was used to represent the sphero-cylindrical errors. Analysis was done for astigmatism with the rule, oblique astigmatism and defocus between the right and left eyes of the subjects, which showed a negative, positive and zero correlation respectively. No correlation could be detected for RMS values between right and left eyes, though Zernike between right and left showed bilateral symmetry in our subjects. It was found that with an increase of spherical aberration, defocus decreased slightly. The validity and repeatability of our Shack–Hartmann aberrometry in measuring the refractive error was analysed and repeatability coefficient calculated. Optimal correction for greater retinal image quality has been discussed and far-point vergence for detecting the point of maximum retinal...
3 citations
TL;DR: In this paper, the influence of decentration of an optical component on the wavefront in an optical system was analyzed using a Shack Hartmann Wavefront Sensor and the experimental results and analyses were presented.
Abstract: Alignment of optical components is one of the important requirements in any optical system. Decentration of a component, like a lens, in the path of the beam, would introduce aberrations of various types. This would affect the measurement accuracy in the optical system such as an interferometer. In this work, we have analyzed the influence of decentration of an optical component on the wavefront in an optical system. The various aberrations caused due to the shifting of the axis of a lens in the path of an optical wavefront have been measured using a Shack Hartmann Wavefront Sensor and their influence studied. One of the lenses in the optical system is moved or decentered in transverse direction by 500 μm in steps of 50 μm. Decentration was done for all four quadrants. For each step, wavefront data is been taken and data was analyzed. Defocus, horizontal coma, vertical coma and spherical aberration were analyzed, apart from peak-to-valley and RMS values. Results showed that the error introduced is minimal up to 300 μm decentration, above which the aberrations were quite large. The experimental results and analyses are presented.
2 citations