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.
References
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TL;DR: This work presents here a technique for direct measurement of the structure function through the use of a Shack-Hartmann wave-front sensor, and confirms that the atmosphere behaves according to Kolmogorov theory most of the time.
Abstract: The phase structure function has been used as a convenient way to characterize aberrations introduced on optical propagation by the atmosphere. It forms the theoretical basis for the calculation of such things as the long- and short-exposure atmospheric transfer function. The structure function is difficult to measure directly and is usually assumed to follow Kolmogorov statistics. We present here a technique for direct measurement of the structure function through the use of a Shack–Hartmann wave-front sensor. Experiments confirm that the atmosphere behaves according to Kolmogorov theory most of the time. However, some instances of non-Kolmogorov behavior have been noted.
130 citations
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01 Aug 1990
TL;DR: The direct control of subaperture wavefront gradients is discussed, in which a single step replaces the multistep process associated with wavefront reconstruction and decoupling.
Abstract: The wavefront sensing and reconstruction algorithms needed for the control signals for the actuators of a deformable mirror when utilizing the Hartmann-Shack wavefront sensing method are discussed. The algorithms determine the actuator's use of the measured data of image displacement to control the mirror. An analysis is presented regarding the limitations inherent in various techniques of wavefront reconstruction. The direct control of subaperture wavefront gradients is discussed, in which a single step replaces the multistep process associated with wavefront reconstruction and decoupling. The single-step process is tested experimentally on a 19-element deformable mirror with subaperture dividing optics and an optical path for purposes of comparison. By increasing the number of fitting terms, coupling can be alleviated, and modal reconstruction is shown to prevent aliasing. Controlling gradients are found to make wavefront correcting more precise by modeling the response function between actuators and subapertures.
122 citations
TL;DR: The overall findings suggest a more prominent role for monochromatic high-order aberrations in degrading the visual image than has hitherto been assumed.
Abstract: We used an apparatus similar to Tscherning's aberroscope, and analyzed subjects' drawings to obtain the wave aberration surfaces of 55 eyes. This analysis permitted a Taylor series representation of the wave aberrations to terms of the fourth order. The results revealed a wide variety in type and severity of high-order aberrations in which "cylindrical" aberrations were prominent and cases of classical spherical aberrations were rare. We computed the monochromatic modulation transfer function curves for the range of observations. The overall findings suggest a more prominent role for monochromatic high-order aberrations in degrading the visual image than has hitherto been assumed.
111 citations
Additional excerpts
...Equations (6) and (7) were reduced into the following matrix equation (8) fSg 1⁄4 fCg1⁄2Z ; (8)...
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TL;DR: The blur on the retina in the horizontal meridian due to monochromatic and chromatic aberrations has been measured using a novel psychophysical technique and in some eyes, coma was present as a result of a displacement of the axis of symmetry from the centre of the pupil, but in three eyes, comma was present without spherical aberration.
Abstract: The blur on the retina in the horizontal meridian due to monochromatic and chromatic aberrations has been measured using a novel psychophysical technique. Longitudinal chromatic aberration gives the dominant blur for pupil sizes of 4-5 mm, followed by monochromatic aberrations, and blur due to optical transverse chromatic aberration. In some eyes, coma was present as a result of a displacement of the axis of symmetry from the centre of the pupil, but in three eyes, coma was present without spherical aberration. The technique also allows a measurement of the effective pupil centre relative to the geometric centre and a partial analysis of the relative positions of the reference axes of the eye.
75 citations
Additional excerpts
...Equations (6) and (7) were reduced into the following matrix equation (8) fSg 1⁄4 fCg1⁄2Z ; (8)...
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...∂∅ðx; yÞ ∂y 1⁄4 Xn k1⁄41 ck ∂Zkðx; yÞ ∂y : (7)...
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...54(7) Optical Engineering 54(7), 075104 (July 2015)...
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TL;DR: A computationally efficient and accurate numerical technique inspired by the slope detection and ranging (SLODAR) method to perform real time turbulence profiling from properly selected Shack-Hartmann wavefront sensor measurements accumulated over a few hundred frames from a pair of laser guide stars, thus eliminating the need for an additional instrument.
Abstract: Real-time turbulence profiling is necessary to tune tomographic wavefront reconstruction algorithms for wide-field adaptive optics (AO) systems on large to extremely large telescopes, and to perform a variety of image post-processing tasks involving point-spread function reconstruction. This paper describes a computationally efficient and accurate numerical technique inspired by the slope detection and ranging (SLODAR) method to perform this task in real time from properly selected Shack–Hartmann wavefront sensor measurements accumulated over a few hundred frames from a pair of laser guide stars, thus eliminating the need for an additional instrument. The algorithm is introduced, followed by a theoretical influence function analysis illustrating its impulse response to high-resolution turbulence profiles. Finally, its performance is assessed in the context of the Thirty Meter Telescope multi-conjugate adaptive optics system via end-to-end wave optics Monte Carlo simulations.
52 citations
Additional excerpts
...>< >: xmþ1 ymþ1 θxmþ1 θymþ1 (9)>= >; 1⁄4 1⁄2ABCD kþ1;mþ1 (8)>< >: xkþ1 ykþ1 θxkþ1 θykþ1 (9)>= >; : (4)...
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...(2)–(4) (8)>< >: xk yk θxk θyk (9)>= >; 1⁄4 1⁄2ABCD i;k (8)>< >: xi yi θxi θyi (9)>= >; ; (2)...
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