Interferometric radius of curvature measurements: an environmental error treatment

Beisswanger, Rolf; Weckerle, M.; Pruß, Christof; Reichelt, Stephan

doi:10.1364/oe.461972

Cited by 5 publications

(2 citation statements)

References 9 publications

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“…A flexible and fast measurement technique is tilted wave interferometry. [5][6][7][8][9] It uses an array of decentered point sources to illuminate the SUT under different angles and therefore compensate the local gradient of the SUT. Therefore the light of each point source generates an interferogram on the camera, with resolvable fringe patterns.…”

Section: Introductionmentioning

confidence: 99%

Ultimate measurement speed for flexible asphere and freeform metrology: TWISS

Schober,

Pruss,

Herkommer

et al. 2024

Optical Instrument Science, Technology, and Applications III

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Asphere and freeform metrology forms the basis of precision optics fabrication. Stitching or scanning methods provide the necessary flexibility, but require measurement times of several minutes. Using parallel information channels of light (wavelength, polarization, phase) in combination with the model-based tilted wave interferometry approach boosts the measurement possibilities. In this proceeding we show how these information channels can be used to enhance the measurement capabilities regarding reconstruction quality and show how the complete shape information of strong aspheres can be recorded by TWISS (tilted wave interferometry single-shot) within milliseconds.

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Section: Introductionmentioning

confidence: 99%

Ultimate measurement speed for flexible asphere and freeform metrology: TWISS

Schober,

Pruss,

Herkommer

et al. 2024

Optical Instrument Science, Technology, and Applications III

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show abstract

“…Because of their excellent symmetry, high-quality spheres are frequently utilized for various applications, including bearings, optical surfaces, and volume definitions, as in the Avogadro project [1]. Furthermore, the precision spheres are considered calibration standards for dimensional measurement devices such as coordinate measuring machines (CMM) and surface profilometers [2].…”

Section: Introductionmentioning

confidence: 99%

Accurate Measurement of Surface Irregularities for a Standard Sphere Using Fizeau Laser Interferometer

Saleh,

Amer,

Nada

2023

Journal of Scientific Research in Science

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Spherical surfaces are essential components in optical systems for different applications. Also, standard spheres are typically employed to calibrate dimensional and mass-measuring instruments. Therefore, measuring and eliminating the surface irregularities of these spheres represents a challenge for modern industries. Surface irregularities can be measured by either the contact method (as stylus profilometers) or the non-contact method (as interferometers). The Fizeau laser interferometer (GPI-XP, Zygo Co.) is typically used to accurately measure surface irregularities for flat surfaces, lenses, and mirrors of 102 mm diameter, and it is not prepared for testing heavy spheres. This work presents a modification for the interferometric system to expand its capability for testing spheres of diameters up to 145 mm and masses up to 2 kg. Also, the modification provides automatic rotation for the tested surfaces (an electric rotating platform) to avoid the disadvantages of manual rotation (a tweezer). At different rotation angles, the measurements are performed on a mass-standard silicon sphere (SiScKg-02-d, PTB Inst.). The average measured value of the surface irregularities is 43.9 nm, with an improved repeatability of 2.8 nm and a minimized measurement uncertainty of ±6.8 nm. The evaluation of the uncertainty budget is also investigated in this study.

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Error analysis of laser interferometric system for measuring radius of curvature

Ahmed

Amer

Nada

2023

J Opt

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Spherical surfaces are essential components of optical systems and imaging devices. Moreover, precision spheres are calibration standards for many accurate instruments in dimensional and mass metrology. A spherical surface's main property is its radius of curvature, which can be measured using contact or non-contact methods. Interferometry is an accurate non-contact technique, but some error sources impact it. This study investigates seventeen error sources that affect a laser interferometric system for measuring the radius of curvature of a precision sphere. The measurements are obtained using a Fizeau laser interferometer (GPI-XP, Zygo) with phase-shifting capability and a displacement measuring interferometer (ZMI-1000, Zygo). A silicon–nitride precision sphere with a nominal radius of 12.49965 mm is dealt with in this study. One of the main contributions of this study is proposing three additional error sources: focal shift, optical distortion, and y-axis vibration. Besides, deadpath, nulling, and focal shift error sources contributed 70% of the total uncertainty budget. Also, to correlate measurement accuracy with the reference surface, three transmission spheres (f/3.3, f/1.5, and f/0.65) are employed; f/0.65 reported the most accurate radius measurement of 12.49922 ± 0.00089 mm. This study also investigates the dependence of the nulling error on the coverage factor that defines the tested surface area. The analysis of the measurement uncertainty and the optimum conditions that minimize the system's potential error sources are described in this work.

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Interferometric radius of curvature measurements: an environmental error treatment

Cited by 5 publications

References 9 publications

Ultimate measurement speed for flexible asphere and freeform metrology: TWISS

Ultimate measurement speed for flexible asphere and freeform metrology: TWISS

Accurate Measurement of Surface Irregularities for a Standard Sphere Using Fizeau Laser Interferometer

Error analysis of laser interferometric system for measuring radius of curvature

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