Wavefront phase measurement of striae in optical glass

Trujillo-Sevilla, Juan M.; Velasco-Ocaña, Miriam; Bonaque-González, Sergio; Belda-Para, Carolina; Ramos, Juan Manuel Sánchez

doi:10.1364/ao.450219

Cited by 15 publications

(6 citation statements)

References 14 publications

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“…The phase camera that we have designed is based on the acquisition of two intensity images at two different focal planes symmetrically shifted from the focal point of the sample, also known as pupil plane. This methodology, named originally as wavefront phase imaging (WFPI), has been applied successfully in other fields such as ophthalmology [8], metrology [9], or microscopy [10], and uses a patented algorithm based on first derivative. Figure 1 depicts the principal differences with other wavefront sensors based on microlenses or gratings Shack Hartmann wavefront sensors.…”

Section: Methodsmentioning

confidence: 99%

A versatile wavefront sensor journey from macroscopic to microscopic applications

Cairós,

Oliva-García,

Pourreza Ghoushchi

et al. 2024

Unconventional Optical Imaging IV

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In this study we have developed a compact and versatile phase camera functioning as a wavefront sensor for macroscopy or microscopy applications. This device records two intensity images at different focal points and, with the integration of an electrically tunable lens (ETL), operates in real time. Working with intensity images allows achieving high resolutions, near the actual CCD/CMOS sensor resolution. Here we show the application of the camera in two very different scenarios, a macroscopic application, where the camera was coupled with a simple lens relay to study the behavior of a deformable mirror (DM); and characterize defocus and astigmatism in optical lenses. On the second example, the camera was attached directly to a microscope using a simple c-mount to follow human blood moving in real time.

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Section: Methodsmentioning

confidence: 99%

A versatile wavefront sensor journey from macroscopic to microscopic applications

Cairós,

Oliva-García,

Pourreza Ghoushchi

et al. 2024

Unconventional Optical Imaging IV

Self Cite

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“…The system consists of a wavefront phase image sensor [ 28 , 33 ], which employs a lens relay to reverse the object space and captures two out-of-focus images on either side of the pupil plane, as depicted in Figure 1 . This approach eliminates the need for mechanical translation or prism stages, by utilizing an ETL.…”

Section: Methodsmentioning

confidence: 99%

Real-Time Wavefront Sensing at High Resolution with an Electrically Tunable Lens

Oliva-García

Cairós

Trujillo-Sevilla

et al. 2023

Sensors

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We have designed, assembled, and evaluated a compact instrument capable of capturing the wavefront phase in real time, across various scenarios. Our approach simplifies the optical setup and configuration, which reduces the conventional capture and computation time when compared to other methods that use two defocused images. We evaluated the feasibility of using an electrically tunable lens in our camera by addressing its issues and optimizing its performance. Additionally, we conducted a comparison study between our approach and a Shack–Hartmann sensor. The camera was tested on multiple targets, such as deformable mirrors, lenses with aberrations, and a liquid lens in movement. Working at the highest resolution of the CMOS sensor with a small effective pixel size enables us to achieve the maximum level of detail in lateral resolution, leading to increased sensitivity to high-spatial-frequency signals.

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“…A special algorithm is used to calculate the phase change based on these two intensity images 9 . The surface phase map is proportional to the relative surface height map 10 .…”

Section: Wave Front Phase Imaging (Wfpi)mentioning

confidence: 99%

New metrology technique for measuring the free shape of a patterned 300mm wafer held vertically

Trujillo-Sevilla

Casanova-González

Roqué-Velasco

et al. 2023

Metrology, Inspection, and Process Control XXXVII

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On product overlay (OPO) is one of the most critical parameters for the continued scaling according to Moore’s law. Without good overlay between the mask and the silicon wafer inside the lithography tool, yield will suffer1. As the OPO budget shrinks, non-lithography process induced stress causing in-plane distortions (IPD) becomes a more dominant contributor to the shrinking overlay budget2. To estimate the process induced in-plane wafer distortion after cucking the wafer onto the scanner board, a high-resolution measurement of the freeform wafer shape of the unclamped wafer with the gravity effect removed is needed. Measuring both intra and inter die wafer distortions, a feed-forward prediction algorithm, as has been published by ASML, minimizes the need for alignment marks on the die and wafer and can be performed at any lithography layer3. Up until now, the semiconductor industry has been using Coherent Gradient Sensing (CGS) interferometry or Fizeau interferometry to generate the wave front phase from the reflecting wafer surface to measure the free form wafer shape3,4,5. In this paper, we present a new method, Wave Front Phase Imaging (WFPI) for generating a very high-resolution wave front phase map of the light reflected off of the patterned silicon wafer surface. The wafer is held vertically to allow for the free wafer shape to be measured without having the wafer shape be impacted by gravity. We show data using a WFPI patterned wafer geometry tool that acquires 16.3 million data points on a 300mm patterned silicon wafer with 65μm spatial resolution using a total data acquisition time of 14 seconds.

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Wavefront phase measurement of striae in optical glass

Cited by 15 publications

References 14 publications

A versatile wavefront sensor journey from macroscopic to microscopic applications

A versatile wavefront sensor journey from macroscopic to microscopic applications

Real-Time Wavefront Sensing at High Resolution with an Electrically Tunable Lens

New metrology technique for measuring the free shape of a patterned 300mm wafer held vertically

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