Embedded optical fiber link interferometer sensors for snapshot surface inspection using the synthetic wavelength technique.

Free-space optical measurement systems can have a direct impact on evaluation systems operational in propagation paths. During propagation via optical fibers, light suffers scattering or interference, causing some output signal loss with an uncertainty outcome. Therefore, this study aims to explore the instant decisions related to the use of single- and multi-mode fiber optics and how they affect the gathering of data from high-speed optical measurement instrument links. The study also seeks to address a number of design methodology aspects and the empirical outcomes related to a surface topography measurement sensor based on fiber optics capable of surface roughness or step-height measurement. The study suggests that the Fourier transform profilometry method (FTP) can overcome the disadvantages of optical metrology sensors (e.g., bulkiness, challenging set-up, high costs, and low speed). However, despite eliminating vertical height problems, the Fourier transform profilometry (FTP) did have some shortcomings for every outcome related to core variables, including the dispersive optical fiber link sensor. The synthetic wavelength method enabled the dispersive optical fiber link sensor to calculate the vertical step height of the selected sample (1 µm). There was improved step-height repeatability, with satisfactory from 20 to 18 nm outcome improvement range. Additional investigations are necessary to establish the compatibility of single- or multi-mode optical fiber sensors with particular instruments, especially those currently preferred for embedded metrology applications.

Synthetic wavelength to increase the snapshot optical sensor's elevated vertical measurement ranges.

Screening manufactured products that are conducted faster to enhance the contemporary manufacture processes and quality is possible by implementing enhanced quality control. Such quality control of manufactured products has increased the market for process-focused precision metrology that can execute evaluations faster while providing significant feedback for the manufacturing system. This investigation examines spatial dispersive interferometry's potential for producing accurate surface profile measurements by emphasizing vertical range measurements and identifying a system that can enable them to increase incrementally while maintaining the results' quality. Thus, this investigation selected Fourier transform profilometry (FTP) to assess surface profile measurements, as it provides the most reliable and fastest outcome data regarding this sensor. Exploring new surface scanning methods is important, as crucial weaknesses hinder several common approaches. As optical metrology sensors are bulky, difficult to establish, and expensive, the investigation will prove that FTP can resolve these restrictions. The investigation uses the synthetic wavelength approach for addressing vertical measurement limitation concerning optical systems for extending surface step height's vertical measurement range. Though it was observed that the FTP technique surmounts the vertical height limitations, certain limitations were also noted, with all outcomes considering key variables, including the scanning objective lens, system resolution, the spectrometer resolution, and diffraction grating. Future examinations must examine a wider vertical range to expand the snapshot spatial dispersive interferometry process's scope. Further, the step-height repeatability is enhanced, showing a good outcome range from 22 to 20 nm.

Development of a spatially dispersed short-coherence interferometry sensor using diffraction grating orders: publisher's note.

This publisher's note amends the author listing and the funding and acknowledgment sections in Appl. Opt.57, 6391 (2017)APOPAI0003-693510.1364/AO.56.006391.

Development of a spatially dispersed short-coherence interferometry sensor using diffraction grating orders.

Modern manufacturing processes can achieve good throughput by requiring that manufactured products be screened by better quality control exercised at a quicker rate. This trend in the quality control of manufactured products increases the need for process-oriented precision metrology capable of performing faster inspections and yielding valuable feedback to the manufacturing system. This paper presents a spatially dispersed short-coherence interferometry sensor using diffraction orders of the zeroth and first order for a diffraction grating introduced as a new compact system configuration for surface profile measurement. In this modified design, the diffraction grating acts as the beam splitter/combiner. Diffractions for the zeroth and first orders are represented by the reference and measurement arms, respectively, of a Michelson interferometer, which reduces the optical path length. This innovative design has been proven effective for determining the step-height repeatability in the sensor range from 27 nm to 22 nm for profiles spanning the step heights of the tested specimens.