Metrology for the production process of aspheric lenses

Beutler, Andreas S.

doi:10.1515/aot-2016-0011

Cited by 17 publications

(12 citation statements)

References 33 publications

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“…In this situation, comparisons are a key factor in gaining new insights. Comparisons [6][7][8][9] have shown that, while some progress has been achieved, further improvements are also necessary. Most of the specimens used in these comparison studies were conventional spherical or aspherical surfaces made of glass.…”

Section: Introductionmentioning

confidence: 99%

Round robin comparison study on the form measurement of optical freeform surfaces

Fortmeier¹,

Schachtschneider²,

Lédl³

et al. 2020

J. Eur. Opt. Soc.-Rapid Publ.

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A round robin comparison of freeform form measurements was carried out by the project partners and stakeholders of a European metrology research project. Altogether six measuring instruments were considered: five different (pointwise and areal) optical devices and one tactile device. Three optical freeform surfaces were used for the comparison measurements, where two specimens were measured by five instruments and one specimen by four instruments. In this paper, the evaluation methods and results of this round robin are presented for the three freeform surfaces made from a temperature-stable material, Super Invar ®. The freeforms had diameters of 40 mm, 50 mm and 100 mm and best-fit radii of 39.75 mm (convex), 40.9 mm (convex) and 423.5 mm (concave). For comparison, the bilateral pointwise differences between the available measurements were calculated. The root-mean-square values of these differences ranged from 15 nm to 110 nm (neglecting spherical contributions) and provided an insight into the status of typical freeform measurement capabilities for optical surfaces.

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Section: Introductionmentioning

confidence: 99%

Round robin comparison study on the form measurement of optical freeform surfaces

Fortmeier¹,

Schachtschneider²,

Lédl³

et al. 2020

J. Eur. Opt. Soc.-Rapid Publ.

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“…CMMs have the advantage of providing absolute form information, but this process is slow and gives only pointwise information [17], even though the point density in the scanning direction can be very high. The tactile devices used in the study were the Isara 400 [18]; MarSurf LD260 Aspheric 3D [19]; UA3P 3D Profilometer [20]; and Taylor Hobson PGI [21].…”

Section: Measurement Methods and Devicesmentioning

confidence: 99%

“…On the other hand, the measurement procedure is contact-less, thereby sparing the surface from potential scratches or digs. The optical point sensors used were MarForm MFU200 Aspheric 3D [19,22] and LuphoScan [23,24].…”

Section: Measurement Methods and Devicesmentioning

confidence: 99%

Interlaboratory comparison measurements of aspheres

Schachtschneider

Fortmeier

Stavridis

et al. 2018

Meas. Sci. Technol.

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The need for high-quality aspheres is rapidly growing, necessitating increased accuracy in their measurement. A reliable uncertainty assessment of asphere form measurement techniques is difficult due to their complexity. In order to explore the accuracy of current asphere form measurement techniques, an interlaboratory comparison was carried out in which four aspheres were measured by eight laboratories using tactile measurements, optical point measurements, and optical areal measurements. Altogether, 12 different devices were employed. The measurement results were analysed after subtracting the design topography and subsequently a best-fit sphere from the measurements. The surface reduced in this way was compared to a reference topography that was obtained by taking the pointwise median across the ensemble of reduced topographies on a Cartesian grid. The deviations of the reduced topographies from the reference topography were analysed in terms of several characteristics including peak-to-valley and root-mean-square deviations. Root-mean-square deviations of the reduced topographies from the reference topographies were found to be on the order of some tens of nanometres up to 89 nm, with most of the deviations being smaller than 20 nm. Our results give an indication of the accuracy that can currently be expected in form measurements of aspheres.

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“…RMS deviations were found to be of the order of tens of nanometres, up to 90 nm in the case of the strong asphere. There have been several advances in optical technologies for asphere measurement (see e.g., [13], [129]) and contact CMSs can be employed (e.g., see [26], [288]). Traceability for these instruments is now in place, thanks to developments in the EMPIR project FreeFORM (see [9] for a summary of the project outputs).…”

Section: Spherical and Aspherical Form Measurement Artefactsmentioning

confidence: 99%