New method for lens thickness measurement by the frequency-shifted confocal feedback

Tan, Yidong; Zhu, Konglin; Zhang, Shulian

doi:10.1016/j.optcom.2016.05.087

Cited by 19 publications

(11 citation statements)

References 18 publications

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“…Considering the high sensitivity of the laser feedback effect, it has great potential for the axial positioning, especially the multilayer lenses or the coated lens with the high anti-reflecting film. Tan [93] When the profilometry is conducted, the objective lens is scanned in the longitudinal direction to obtain the defocus response curve, locating the sample surface. After that, scanning the sample in the horizontal direction and simultaneously detecting the feedback light intensity.…”

Section: Lens Thickness Measurementmentioning

confidence: 99%

“…Considering the high sensitivity of the laser feedback effect, it has great potential for the axial positioning, especially the multilayer lenses or the coated lens with the high anti-reflecting film. Tan [93] proposed a new method to realize the lens thickness and air gap measurement, as shown in Figure 22. The annular pupil is inserted into the path before the objective lens to create the annular beam, in order to reduce the axial aberration and decrease the positioning error.…”

Section: Lens Thickness Measurementmentioning

confidence: 99%

“…LD, laser diode; Grin Lenses, graded index lenses; BS, beam splitter; AOM1 and AOM2, acousto-optic modulators; BE, beam expander; AP, annular pupil; Obj, objective lens; L, lenses; PD, photo detector; RF, reference signal generator; St, Stage; LIA, lock-in amplifier; PC, computer. (Figure reproducedfrom Ref [93]…”

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confidence: 99%

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Frequency-Shifted Optical Feedback Measurement Technologies Using a Solid-State Microchip Laser

et al. 2018

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Since its first application toward displacement measurements in the early-1960s, laser feedback interferometry has become a fast-developing precision measurement modality with many kinds of lasers. By employing the frequency-shifted optical feedback, microchip laser feedback interferometry has been widely researched due to its advantages of high sensitivity, simple structure, and easy alignment. More recently, the laser confocal feedback tomography has been proposed, which combines the high sensitivity of laser frequency-shifted feedback effect and the axial positioning ability of confocal microscopy. In this paper, the principles of a laser frequency-shifted optical feedback interferometer and laser confocal feedback tomography are briefly introduced. Then we describe their applications in various kinds of metrology regarding displacement measurement, vibration measurement, physical quantities measurement, imaging, profilometry, microstructure measurement, and so on. Finally, the existing challenges and promising future directions are discussed.

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Section: Lens Thickness Measurementmentioning

confidence: 99%

“…Considering the high sensitivity of the laser feedback effect, it has great potential for the axial positioning, especially the multilayer lenses or the coated lens with the high anti-reflecting film. Tan [93] proposed a new method to realize the lens thickness and air gap measurement, as shown in Figure 22. The annular pupil is inserted into the path before the objective lens to create the annular beam, in order to reduce the axial aberration and decrease the positioning error.…”

Section: Lens Thickness Measurementmentioning

confidence: 99%

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Frequency-Shifted Optical Feedback Measurement Technologies Using a Solid-State Microchip Laser

et al. 2018

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“…Also, the measurement procedure needs to be combined with the rotation of the sample at high precision angles. Another method proposed by Tan et al 101,102 combining the confocal effect and frequency shift feedback, which is noncontact, nondestruction, and highly sensitive, can be applied in measurement not only of the thickness but also between the air gap. The schematic setup of the system is shown in Fig.…”

Section: Thickness Measurementmentioning

confidence: 99%

Laser feedback interferometry and applications: a review

Niu

2017

Opt. Eng

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The progress on laser feedback interferometry technology is reviewed. Laser feedback interferometry is a demonstration of interferometry technology applying a laser reflected from an external surface, which has features including simple structure, easy alignment, and high sensitivity. Theoretical analysis including the Lang-Kobayashi model and three-mirror model are conducted to explain the modulation of the laser output properties under the feedback effect. In particular, the effect of frequency and polarization shift feedback effects are analyzed and discussed. Various applications on various types of lasers are introduced. The application fields range from metrology, to physical quantities, to laser parameters and other applications. The typical applications of laser feedback technology in industrial and research fields are discussed. Laser feedback interferometry has great potential to be further exploited and applied.

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“…Previous researchers have investigated lower surface distance measurement methods for transparent plane-parallel plates and lenses based on the chromatic confocal sensor 16 , 17 . Various novel modified models have also been proposed for precision measurements of the lower surface profile of thin transparent components, e.g., frequency-shifted confocal feedback, 18 adaptive modal decomposition, 19 biaxial optical scheme with inclined illumination, 20 and so on 21 , 22 . But these methods are only applicable to plane-parallel plates, and there is still non-negligible error when it comes to curved components.…”

Section: Introductionmentioning

confidence: 99%

Bilateral form characterization of curved transparent components using chromatic confocal sensor

Wu,

Zhao,

Jiang

et al. 2023

Opt. Eng.

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To accurately characterize the geometric form of key components in industrial products, many profile measuring instruments have been developed to date. However, there are some special components, such as the hemispherical resonators featuring thin curved transparent surfaces, which are difficult to be measured using general instruments. The chromatic confocal technology was introduced in this paper to conduct the bilateral form characterization of this type of surfaces. Based on the assumption of tilted plate approximation, a modified ray tracing model was presented to correct the errors produced by the curved surfaces. The experiment of measurement on tilted, fused silica plates was conducted to demonstrate the effectiveness of the proposed model. Results show that the developed model improves the measurement accuracy of plates with large tilt angle. A three-axis motion stage was built with self-developed chromatic confocal sensor to obtain the bilateral profiles of the resonator. By fitting the spheres with the scanning profiles, the form error between the measurement points and the fitted spheres can be calculated. Partial form errors along the circumferential and axial directions of the resonator are evaluated, and an intuitive assessment of its thickness variation along the circumferential direction was made.

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New method for lens thickness measurement by the frequency-shifted confocal feedback

Cited by 19 publications

References 18 publications

Frequency-Shifted Optical Feedback Measurement Technologies Using a Solid-State Microchip Laser

Frequency-Shifted Optical Feedback Measurement Technologies Using a Solid-State Microchip Laser

Laser feedback interferometry and applications: a review

Bilateral form characterization of curved transparent components using chromatic confocal sensor

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