Simultaneous measurement of linear and transverse displacements by laser self-mixing

Ottonelli, Simona; Dabbicco, Maurizio; Lucia, Francesco De; Scamarcio, Gaetano

doi:10.1364/ao.48.001784

Cited by 17 publications

(8 citation statements)

References 7 publications

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“…from moderate to weak or vice versa) which may require further signal processing [1], [2]. A look into large displacement SM sensors reported earlier indicates that the use of co-operative targets has allowed avoiding speckle effect [5] and even helped in improving measurements by an order of magnitude [9]. On the other hand, long range SM displacement sensing has also been achieved by electronically keeping the operating point of the SM interferometer fixed at the half-fringe [10] though the sensor still requires additional optical components.…”

Section: Introductionmentioning

confidence: 99%

“…S ELF-MIXING (SM) or optical feedback interferometry [1]- [3] has been regularly used for displacement sensing [4], [5] though the presence of speckle [6] has often reduced the range or even the possibility of correct measurement. Traditionally, efforts have been invested to avoid speckle, mostly by tracking the strong signal by means of electro-mechanical actuators.…”

Section: Introductionmentioning

confidence: 99%

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Self-Mixing Laser Sensor for Large Displacements: Signal Recovery in the Presence of Speckle

2013

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Laser self-mixing (SM) sensors are successfully used to measure displacement in the absence of speckle. However, speckle deforms the SM signal rendering it unusable for standard displacement extraction techniques. This article proposes a new signal-processing technique, based on tracking the signal envelope, to remedy this problem. Algorithm was successfully employed to measure long-range displacements (25 mm), in the presence of speckle and the lateral movement of the target, both causing severe corruption of the SM signal. It therefore enabled the use of the sensor on noncooperative targets without the need for sensor positioning and/or alignment. The results have been obtained for SM signals in which the envelope amplitude is varied by a factor of 28, without the loss of interferometric fringes. The use of this technique effectively removes the need for opto/electromechanical components traditionally used to measure long-range displacement in the presence of speckle.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Self-Mixing Laser Sensor for Large Displacements: Signal Recovery in the Presence of Speckle

2013

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“…In the first case, a diffusive target can be employed to reduce the backscattered radiation re -entering the laser source; however, this solution implies a signal fading over long-distances due to the speckle effect. The alternative choice is represented by the reduction of the distance between the laser diode and the collimating lens, in order to obtain a divergent laser beam whose power losses through the finite aperture optical elements (lens and diode facet) will compensate the linear increase of the feedback parameter C with the target distance with no need of attenuation filter along the optical path [19].…”

Section: Measurement Of Linear Displacementsmentioning

confidence: 99%

A self-mixing laser sensor for the real-time correction of straightness/flatness deviations of a linear slide

Ottonelli¹,

Dabbicco²,

Lucia³

et al. 2009

Optical Sensors 2009

Self Cite

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The development of a contactless sensor based on the Laser-Self-Mixing effect for the simultaneous measurement of linear and transverse degrees-of-freedom (DOFs) of a moving target is described in this paper. The sensor is made of three laser diodes with integrated monitor photodiodes, and a properly designed reflective target attached to the moving object. The proposed technique exploits the differential measurement of linear displacements by two identical self-mixing interferometers (SMIs) and makes the system more compact and easier to align with respect to traditional interferometric systems, thus providing an effective low-cost motion control system. The feasibility of the proposed sensor is experimentally demonstrated over a range of 1 m for linear motion and +/- 6 mm for transverse displacements, with resolutions of 0.7 mu m and 20 mu m, respectively

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“…Even if speckle occurs [11], SM operating regime can be made stable [12]. As each fringe corresponds to half wavelength (λ/2) target displacement so λ/2 sensor resolution can be easily achieved by using classical fringe counting [13].…”

Section: Introductionmentioning

confidence: 99%

Hardware implementation of metric algorithms for a self-mixing laser interferometric sensor

Amin

Zabit

Hussain

et al. 2016

2016 19th International Multi-Topic Conference (INMIC)

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Self-mixing interferometry (SMI) has been widely used for sensing of diverse vibration, velocity, displacement, biomedical and flow applications. The simplicity of the SMI configuration enables the design of a low-cost, self-aligned and compact sensor with a small optical component count. SMI occurs when a small portion of emitted coherent optical beam is backscattered by the remote target and re-enters the laser cavity, causing interference. Under SMI, the employed laser diode simultaneously acts as a laser source, coherent detector, as well as micro-interferometer. This simple sensor design configuration, however, comes at a price of complex signal processing algorithms, because the SMI signals have rich characteristics as a function of optical feedback level. The purpose of this research work is to implement two of these algorithms, time-frequency signal processing (TFSP) and Consecutive samples based Unwrapping (CSU) in hardware so that real-time displacement and vibration measurements with nanometric precision can be retrieved from the SM sensor in an embedded, autonomous manner. We implemented and tested both algorithms on a Xilinx ZYBO Zynq 7000 development board using VHDL. Results show that our design of CSU algorithm is capable of operating at 432 MHZ minimum clock frequency and latency of 3 clock cycles. Our CSU design consumes 159 slice registers and 215 LUT's, and draws 0.70 watts of onboard power. While the design of TFSP algorithm is capable of operating at 363.3 MHZ clock frequency and latency of 570k clock cycles. TFSP design consumes 5056 slice registers and 5192 LUT's, and draws 0.8 watts of onboard power.

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Simultaneous measurement of linear and transverse displacements by laser self-mixing

Cited by 17 publications

References 7 publications

Self-Mixing Laser Sensor for Large Displacements: Signal Recovery in the Presence of Speckle

Self-Mixing Laser Sensor for Large Displacements: Signal Recovery in the Presence of Speckle

A self-mixing laser sensor for the real-time correction of straightness/flatness deviations of a linear slide

Hardware implementation of metric algorithms for a self-mixing laser interferometric sensor

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