Multi-dimensional, non-contact metrology using trilateration and high resolution FMCW ladar

Mateo, Ana Baselga; Barber, Zeb W.

doi:10.1364/ao.54.005911

Cited by 15 publications

(4 citation statements)

References 11 publications

(13 reference statements)

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“…Benefits of the FMCW ladar metrology method include removing the requirement to continuously track a target, as in standard CW interferometry; the ability to range to multiple surfaces (targets) simultaneously such as multiple surfaces in transparent solids or for resolving small stepped features on surfaces; and high coherent sensitivity allowing high resolution, precision, and accuracy measurements to diffuse targets with inherent insensitivity to stray light. Finally, in a separate article, we describe and demonstrate a new concept for extending the FMCW ladar system to multidimensional trilateration-based metrology [4].…”

Section: Resultsmentioning

confidence: 99%

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Precision and accuracy testing of FMCW ladar-based length metrology

Mateo

Barber

2015

Appl. Opt.

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The calibration and traceability of high-resolution frequency modulated continuous wave (FMCW) ladar sources is a requirement for their use in length and volume metrology. We report the calibration of FMCW ladar length measurement systems by use of spectroscopy of molecular frequency references HCN (C-band) or CO (L-band) to calibrate the chirp rate of the FMCW sources. Propagating the stated uncertainties from the molecular calibrations provided by NIST and measurement errors provide an estimated uncertainty of a few ppm for the FMCW system. As a test of this calibration, a displacement measurement interferometer with a laser wavelength close to that of our FMCW system was built to make comparisons of the relative precision and accuracy. The comparisons performed show <10 ppm agreement, which was within the combined estimated uncertainties of the FMCW system and interferometer.

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Section: Resultsmentioning

confidence: 99%

“…Moreover, spreading the pulse in time also lowers the peak optical powers, making it more compatible with fiber optic amplification and delivery. These benefits have made FMCW ladar a promising solution for many ranging systems in addition to noncontact and standoff metrology [3,4].…”

Section: Introductionmentioning

confidence: 99%

Precision and accuracy testing of FMCW ladar-based length metrology

Mateo

Barber

2015

Appl. Opt.

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“…For these noncooperative targets, the farthest detectable stand-off distance is much shorter, and the precision is lower because the weak echo power cannot provide a desirable signal intensity higher than the noise. To strengthen the signal-to-noise ratio (SNR), many efforts have been made [18,[24][25][26]. A direct way is to increase the probe-beam power.…”

Section: Introductionmentioning

confidence: 99%

Frequency-swept feedback interferometry for noncooperative-target ranging with a stand-off distance of several hundred meters

Wang

Dai

et al. 2022

PhotoniX

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Frequency-swept interferometry (FSI) is a powerful ranging method with high precision and immunity to ambient light. However, the stand-off distance of the current FSI-based ranging system for noncooperative targets is relatively short because the weak echo power cannot provide the needed signal-to-noise ratio (SNR). Here, we report a ranging method that combines FSI and the laser feedback technique. Compared with conventional FSI, the interference between the weak echo signal and the local oscillator occurs in the laser cavity, which enhances the signal spontaneously and then provides an improved SNR. In the experiments, the detection limit of the echo power is less than 0.1 fW, with a 1 mW probe beam. Based on the enhancement from the laser feedback technique, the system can detect a noncooperative target that is up to hundreds of meters away in space without extra optical amplifiers. On the other hand, a large stand-off distance makes the system sensitive to environmental disturbance, which degrades the ranging precision. To address this issue, an interferometry-based compensation device, which is also sensitive to weak echoes from noncooperative targets, is proposed to monitor the optical-path-length drifts and ensure accurate beat frequency recognition. Moreover, the device can record distance changes during the integration time of ranging and track a moving target precisely with improved temporal resolution. Owing to the high sensitivity and the validity of the compensation approach, the standard deviation in 10 measurements is better than 0.07 mm when targeting an aluminum sheet at approximately 152 m. Generally, with a large range, high relative precision, and low photon consumption, the novel technical scheme for laser ranging demonstrates new capabilities that promise to enable a wide range of applications, such as large equipment assembly and noncooperative-target tracking.

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“…The inverse problem then is to determine the scene that caused the measurements. Examples include coherent optical holographic lensless imaging [11], [12] using tunable lasers, and tomographic mammography using microwave radio [4]. Holographic ultrasound sonar for underwater applications has a long history [5], [6] where traditional sonar techniques like the so-called A-mode and C-mode (respectively depth and scanned sonar), with continuous frequency modulation and acoustic lenses, were used.…”

Section: Introductionmentioning

confidence: 99%

Design of a pseudo-holographic distributed time-of-flight sonar range-imaging system

Streeter

Scott

Lickfold

et al. 2016

2016 International Conference on Image and Vision Computing New Zealand (IVCNZ)

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The design of an audible sonar distributed sensor time-of-flight range imaging system is investigated, sonar being chosen as a substitute for optical range imaging due to cost and simplicity of implementation. The distributed range imaging system proposed is based on the holographic principle where the sensors detect the self interference of the reflected sound from the scene, and the Fourier analysis computes the reflected object profile. An approximate linearised model used in related holographic imaging techniques is found to be inappropriate for the design, and qualitative assessment of simulations show that removing the linearisation dramatically improves image reconstruction. Quantitatively the nonlinear reconstruction improves the RMSE by a factor of 1.3-2.1 times. The full nonlinear reconstruction is slow, and mathematical development lead to 15 fold reduction in computation time.

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Multi-dimensional, non-contact metrology using trilateration and high resolution FMCW ladar

Cited by 15 publications

References 11 publications

Precision and accuracy testing of FMCW ladar-based length metrology

Precision and accuracy testing of FMCW ladar-based length metrology

Frequency-swept feedback interferometry for noncooperative-target ranging with a stand-off distance of several hundred meters

Design of a pseudo-holographic distributed time-of-flight sonar range-imaging system

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