Measuring surface slope error on precision aspheres

Kumler, James J.; Caldwell, J. Brian

doi:10.1117/12.753832

Cited by 5 publications

(2 citation statements)

References 2 publications

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“…Often inadequate tolerances are discovered "the hard way"; that is after all the manufactured optical components are assembled but the completed optical system fails to perform to its overall optical performance specifications. Some published examples include a 300x zoom system that needed a tolerance on local slope for key aspheric elements [4], optics for the National Ignition Facility (NIF) laser system that required power-spectral density (PSD) specifications [5], and wide-field aspheric camera lens suffering from localized artifacts in the center of the lens [6]. Surface form errors of the sort shown in figures 5 and 6 are often termed "mid-spatial frequency" (MSF) errors, and PV irregularity will often be…”

Section: Discussion Of Estimator Errormentioning

confidence: 99%

Updating the peak-to-valley (PV) irregularity specification for the modern world

Murphy

2023

Optifab 2023

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Communicating fabrication tolerances is a vital part of the optical manufacturing process. The most common surface form tolerance is peak-to-valley (PV) irregularity, and its specification and evaluation has largely remained unchanged for decades. Fabrication, testing, and computation capabilities, however, have evolved considerably over that time, exposing PV's extreme sensitivity to outlier data points. When everyone was using the same measurement and analysis technique (visual inspection of test plate interferograms), this sensitivity was of secondary concern to ease of computation. Today, however, numerous measurement techniques are viable for evaluating surface form, computation power is cheap, and different measurements of the same surface can easily result in wildly different PV results. This creates confusion as to whether a surface conforms to tolerance or not.To address this issue, we propose standardized methods for evaluating a PV tolerance value that are resistant to outliers. We first provide an example of the problem on an actual surface measurement and demonstrate how trimmed PV estimators can mitigate it. We review two such estimators, robust peak valley (PVr) and clipped peak-to-valley (PV%). We then review the conceptual trade-offs involved with choosing an appropriate estimator and demonstrate estimator behavior on a variety of simulated surface profiles. Finally, we explore the challenges in adopting a more reliable PV metric and outline the plans for updating the ISO 10110-5 surface form standard to achieve this.

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Section: Discussion Of Estimator Errormentioning

confidence: 99%

Updating the peak-to-valley (PV) irregularity specification for the modern world

Murphy

2023

Optifab 2023

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“…These midspatial frequency surface errors can lead to reduced system resolution, stray light, reduced uniformity of the illumination system, and so on [25]. Therefore the influence of midspatial frequency surface errors on the ASPALs needs to be considered besides the surface irregularities characterized by PV and RMS [26][27][28][29][30][31].…”

Section: Consideration Of Mid-spatial Frequency Surface Errors For Aspalmentioning

confidence: 99%

The Current Situation of Family Education and School and Kindergarten Admission of Migrant Children in Zhejiang Province, China: A Survey of Hangzhou, Ningbo and Jiaxing

Gao

Feng

et al. 2020

EJES

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Based on a survey of 322 parents of migrant children aged 3 to 10 in Hangzhou, Ningbo and Jiaxing, Zhejiang Province, China, the study found that nearly 70% of parents have been working in Zhejiang for 5-10 years, and 28% of them have worked for more than 10 years; 94% of them hold agricultural household registration and 6% of them hold non-agricultural household registration. Nearly 70% of these families have 2 to 3 children and 16% of them have 4 children. Those children who can get into the local public kindergartens and primary schools are all study in the local institutions and most school-aged children and the majority of pre-school children who do not meet the admission requirements for local public kindergartens and primary schools return to their hometown due to the pressure of tuition fees. At the same time, family education is not efficient, more than half of the children’s spare time is occupied by television and video games, the proportion of reading and sports activities is only a little more than 10%. Most parents have little time to read, do homework and physical exercise with their children, because of their heavy work or low level of education. This paper puts forward some relevant countermeasures and suggestions, hoping to change this situation. Article visualizations:<img src="/-counters-/edu_01/0629/a.php" alt="Hit counter" />

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