How to use manufacturing statistics when tolerancing a lens system

Kaufman, Morris I.; Malone, Robert M.; Frayer, Daniel K.; Griffin, Gavin O.; Light, Brandon

doi:10.1117/12.2632109

Cited by 3 publications

(5 citation statements)

References 3 publications

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“…In the middle row "Monte Carlo default" are provided the statistics from a Zemax MC analysis with default settings, used in the initial analysis; and in the bottom rows of (a-c) are statistics from an MC analysis where a user-defined distribution was written to estimate the manufacturing data in the improved tolerance model, as the default distribution differed visibly from the measured values. Surface irregularity and wedge are inherently bimodal with no probability of having zero error [3], so a normal distribution incorrectly describes these parameters. A Gaussian fit of the thickness manufacturing data was visually similar and had a standard deviation and mean each with <5% difference from the MC default, so its statistics were left unchanged from the initial analysis.…”

Section: Tolerancing Manufacturing Statisticsmentioning

confidence: 99%

“…It remains a debated topic what level of detail is needed in the tolerance model; although more detail may mean more time spent on the analysis, an overly optimistic model may lead to development of an uncompliant system that will incur costs and delays, whereas an overly pessimistic model may also incur costs of unnecessarily precise manufacturing and mounting strategy, or the rejection of actually compliant designs [2,3]. These trade-offs are considered in an investigation of the tolerance model of an optical system whose initial prediction of wavefront error (WFE) was overly pessimistic; and by means of this investigation, to understand which aspects of the manufacturing and assembly need to be added to the tolerance model to agree with the as-built data, and which might be generalizable to tolerance analyses of other systems.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of tolerancing simulations and as-built optical performance in a precision optical system

Calvano,

Matia-Hernando,

Parwez

et al. 2024

Optical Design and Engineering IX

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To properly account for imperfections in fabrication of lenses and mechanics as well as optics alignment limitations, it is necessary to run a tolerance analysis during the optical design process. But it is often unclear what level of detail the tolerance model necessitates to accurately predict the variation in performance, and there are consequences of time and money for both overly optimistic and overly pessimistic designs. In this work, we compare the assembly results of a precision microscope objective with an initially overly pessimistic tolerance analysis and develop an improved tolerance model in agreement with the performance of as-built systems. The system is analyzed in two industry-standard optical design software packages, Zemax and CODE V, and the results are compared with each other and with assembly data. The Zemax Monte Carlo analysis agrees with as-built data by including manufacturing and assembly tolerance statistics as well as by modelling compensation procedures used in the lab. Analyses in CODE V's TOR and Monte Carlo yield consistently similar results to each other but are more pessimistic than the Zemax analysis. All three methods are found in agreement by reducing the irregularity tolerance on CODE V analyses to reflect the software's differing tolerance definitions. Although much faster, CODE V's TOR is unable to model complex compensation procedures, suggesting that a preliminary analysis in TOR should be followed by a more thorough Monte Carlo analysis to avoid overspecification of components. Several aspects of the tolerance model developed here are generalizable to other systems.

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Section: Tolerancing Manufacturing Statisticsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Comparison of tolerancing simulations and as-built optical performance in a precision optical system

Calvano,

Matia-Hernando,

Parwez

et al. 2024

Optical Design and Engineering IX

View full text Add to dashboard Cite

show abstract

“…Material tolerances consist of the refractive index and Abbe number of glasses but can also include the coefficients of thermal expansion of the glass and metal components in athermalized designs [1]. Manufacturing tolerances are comprised of the radii of curvature and irregularity of optical surfaces [2], the sags and center thicknesses of lenses, the lengths of mechanical spacers and cells, and the wedge between the optical and mechanical axes of lenses [3]. Lastly, assembly tolerances pertain to the decenters, tilts, and rolls of the optical and mechanical components.…”

Section: Introductionmentioning

confidence: 99%

“…Upon request, they can also produce inspection reports of the refractive index of their glasses at a discrete set of wavelengths [4]. Meanwhile, manufacturers of optical components and companies with large inspection data sets often share their insights on the probability distributions of the manufacturing tolerances of the components they make and procure [2,3].…”

Section: Introductionmentioning

confidence: 99%

Optomechanical analysis of the alignment tolerance of threaded lens mounts

Tangari Larrategui,

Camacho,

Tulungen

et al. 2023

Optomechanical Engineering 2023

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Threaded mounts are one of the most common interfaces between optical systems and commercial-off-the-shelf cameras. Popular examples include the established C-mount, as well as the newer TFL-mount which accommodates for larger sensor formats such as the APS-C detector. In all cases, the thread is used to adjust for focus by clocking the optical system with respect to a fixed camera assembly or vice versa. For this reason, the alignment between the datum axis of the optical system and the array detector plane inside the camera depends on both the allowances and tolerances of the thread interface, and on the manufacturing tolerances of the mount components. To highlight how the stack up of these tolerances can affect image quality of an optical system, we first perform an inverse sensitivity analysis to determine the detector alignment specification as a function of system F/#, field of view, and chief ray angle. We then calculate the misalignment contributions of the thread between the optical system and the lock ring that sets the camera axial position for best focus. This optomechanical analysis allows us to determine if thread mounts are appropriate for the specifications of the optical system under consideration and to specify the tolerances of the thread interface when this is the case.

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“…In order to reduce the depth of the zoom lens to less than 6.5 mm, the circular aperture lens is replaced by a rectangular aperture lens. Finally, the design performance is discussed and a tolerance analysis [ 16 ] is performed to evaluate the manufacturability of the lenses.…”

Section: Introductionmentioning

confidence: 99%

Optical Design of a Miniaturized 10× Periscope Zoom Lens for Smartphones

2023

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The size of the optical zoom system is important in smartphone camera design, especially as it governs the thickness of the smartphone. We present the optical design of a miniaturized 10× periscope zoom lens for smartphones. To achieve the desired level of miniaturization, the conventional zoom lens can be replaced with a periscope zoom lens. In addition to this change in the optical design, the quality of the optical glass, which also affects the performance of the lens, must be considered. With advancements in the optical glass manufacturing process, aspheric lenses are becoming more widely used. In this study, aspheric lenses are incorporated into a design for a 10× optical zoom lens with a lens thickness of less than 6.5 mm and an eight-megapixel image sensor. Furthermore, tolerance analysis is carried out to prove its manufacturability.

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How to use manufacturing statistics when tolerancing a lens system

Cited by 3 publications

References 3 publications

Comparison of tolerancing simulations and as-built optical performance in a precision optical system

Comparison of tolerancing simulations and as-built optical performance in a precision optical system

Optomechanical analysis of the alignment tolerance of threaded lens mounts

Optical Design of a Miniaturized 10× Periscope Zoom Lens for Smartphones

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