Microscope Optics

Groß, Herbert; and, Fritz Blechinger; Achtner, Bertram

doi:10.1002/9783527699247.ch7

Cited by 3 publications

(3 citation statements)

References 57 publications

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“…This ratio typically limits the applicable numerical aperture (NA) of the imaging system and thus controls the maximal achievable lateral and/or depth resolution. In classical imaging systems, the resolution is directly related to the NA or f -number (f#) of the optical system which are related by [4][5][6][7][8]:…”

Section: General Aspects About Optical Measurementsmentioning

confidence: 99%

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3D optical measurement techniques

Engel

2022

Meas. Sci. Technol.

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The field of optical 3D metrology is gaining significant interest in the past years. Optical sensors can probe the geometry of workpieces and biological samples very fast, highly accurate and without any tactile physical contact to the object’s surface. In this respect, optical sensors are a pre-requisite for many applications in the big trends like Industrial Internet of Things (IIoT), Industry 4.0 or Medicine 4.0. The interest for optical 3D metrology is shifting from a metrology for quality assurance in industrial production to “digitize the real world“ to facilitate a precise digital representation of an object or an environment for documentation or as input data for virtual applications like digital fab or augmented reality. The aspiration to digitize the world necessitates fast and efficient contact free sensing principles of appropriate accuracy for solid and even soft objects with a variety of colour, surface texture and lighting conditions. This review article tries to give a concise conceptual overview about the evolution of a broad variety of optical measurement principles that evolved and gained some importance in the field of 3D metrology for industrial 3D applications and their related technological enablers.

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Section: General Aspects About Optical Measurementsmentioning

confidence: 99%

“…The depth of field concept (DoF) describes the depth resolution of an optical system. The DoF is a function of the respective wavelength lambda and the NA of the optics and often referred to as Rayleigh length [5,8]:…”

Section: General Aspects About Optical Measurementsmentioning

confidence: 99%

3D optical measurement techniques

Engel

2022

Meas. Sci. Technol.

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“…Some works have already been published, notably by taking a linear filtering operation approach [10,14]. However, the assumption that the point spread function (PSF) of the imaging system is identical throughout the FOV (shift invariance) is required which is not necessarily valid, especially for high NA MO or when the Petzval field curvature is not corrected [15]. Moreover, image distortion in the imaging system is not considered even though it is clear that distortion also produces a surface error.…”

Section: Surface Error Investigationmentioning

confidence: 99%

Correction of spherical surface measurements by confocal microscopy

Béguelin

Scharf

Noell

et al. 2020

Meas. Sci. Technol.

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Refractive microlenses are nowadays widely used in optical systems. Characterizing their surface is essential to ensure their quality and to optimize their fabrication process. This is realized by optical surface profilers thanks to their vertical resolution, short measurement time and areal information. However, when measuring non-flat surfaces, errors appear caused by aberrations of the microscope objective used in such systems, which significantly limit the achievable quality of the manufactured spherical surfaces. Approaches have been proposed to tackle these errors, but none of them demonstrated its validity for measurements of high quality microlenses. In this work, we demonstrate that the surface error depends on the surface position within the field of view of the microscope objective and on the surface slope. We then explain how to record the value of this error experimentally: this can be done by measuring a reference ball placed at different positions in the field of view. We finally use a machine learning algorithm to fit the experimental data in order to correct subsequent measurements. We apply this approach to measurements performed by a 20× numerical aperture 0.6 microscope objective of a confocal microscope. The effectiveness of the proposed method is demonstrated by showing that the surface error corresponds to a RMS wavefront error of λ/7 before correction and of λ/50 after correction for glass microlenses used in the visible range. This method thus allows the use of high numerical aperture microscope objectives for an accurate characterization of microlenses. Likewise, the fabrication capability of microlenses in terms of slope and quality is greatly extended, which is especially important for aspheres or freeforms.

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Corr objective: historical development and some theory

Zhang,

Hanft

2024

International Optical Design Conference 2023

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Microscope Optics

Cited by 3 publications

References 57 publications

3D optical measurement techniques

3D optical measurement techniques

Correction of spherical surface measurements by confocal microscopy

Corr objective: historical development and some theory

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