A Method Toeliminate the Backlash Error of Tunable Laser

Chengzhi, 相成志 Xiang; Wei, 龚威 Gong; Xin, 马昕 Ma; Xuewu, 程学武 Cheng

doi:10.3788/aos201434.0912003

“…The laser of the target wavelength is generated via difference frequency mixing between the fundamentals of the Nd:YAG laser (1064 nm) and the dye laser (634 nm), which is pumped by the second harmonic of the Nd:YAG (532 nm). As a consequence, the wavelength of the output laser can be changed by tuning the dye laser whose wavelength is changed by a stepper motor [18] . The fluctuation of laser emission system which takes dye laser as the source of tunable laser is high, about 10% at around 1.6 um region.…”

Section: Resultsmentioning

confidence: 99%

ON-LINE WAVELENGTH CALIBRATION OF PULSED LASER FOR CO<sub>2</sub> DIFFERENTIAL ABSORPTION LIDAR

Xiang¹,

Ma²,

Han³

et al. 2016

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

0

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Commission I, WG I/2KEY WORDS: On-line wavelength calibration, Pulsed laser, Multi-wavelength scanning, Energy matching ABSTRACT:Differential absorption lidar (DIAL) remote sensing is a promising technology for atmospheric CO 2 detection. However, stringent wavelength accuracy and stability are required in DIAL system. Accurate on-line wavelength calibration is a crucial procedure for retrieving atmospheric CO 2 concentration using the DIAL, particularly when pulsed lasers are adopted in the system. Large fluctuations in the intensities of a pulsed laser pose a great challenge for accurate on-line wavelength calibration. In this paper, a wavelength calibration strategy based on multiwavelength scanning (MWS) was proposed for accurate on-line wavelength calibration of a pulsed laser for CO 2 detection. The MWS conducted segmented sampling across the CO 2 absorption line with appropriate number of points and range of widths by using a tunable laser. Complete absorption line of CO 2 can be obtained through a curve fitting. Then, the on-line wavelength can be easily found at the peak of the absorption line. Furthermore, another algorithm called the energy matching was introduced in the MWS to eliminate the backlash error of tunable lasers during the process of on-line wavelength calibration. Finally, a series of tests was conducted to elevate the calibration precision of MWS. Analysis of tests demonstrated that the MWS proposed in this paper could calibrate the on-line wavelength of pulsed laser accurately and steadily.

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“…Nevertheless, the influences of other parameters, such as the noise of an infrared detector, will also cause some errors in the calibration of an on-line wavelength. The on-line wavelength calibration of dye laser emission system is also affected by the backlash error of the tunable laser, and this condition generates large errors as it conducts the wavelength adjustment through mechanical rotation [22]. The calibration of on-line wavelength should be more stringent to achieve accurate detection of atmospheric CO 2 by the DIAL of pulsed laser; otherwise, huge influences will be encountered and cause an incorrect inversion result.…”

Section: Introductionmentioning

confidence: 99%

Wavelet modulus maxima method for on-line wavelength location of pulsed lidar in CO_2 differential absorption lidar detection

Gong

¹

,

Xiang

²

,

Mao

³

et al. 2016

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Differential absorption lidar (DIAL) is an excellent technology for atmospheric CO 2 detection. However, the accuracy and stability of a transmitted on-line wavelength are strictly required in a DIAL system. The fluctuation of a tunable pulsed laser system is relatively more serious than that of other laser sources, and this condition leads to a large measurement error for the lidar signal. These concerns pose a significant challenge in on-line wavelength calibration. This study proposes an alternative method based on wavelet modulus maxima for the accurate on-line wavelength calibration of a pulsed laser. Because of the different propagation characteristics of the wavelet transform modulus maxima between signal and noise, the singularities of a signal can be obtained by detection of the local modulus maxima in the wavelet transform maximum at fine scales. Simulated analysis shows that the method is more accurate than the general method such as quintic polynomial fitting and can steadily maintain high calibration precision at different signal-to-noise ratios (SNRs). Last, 16 groups of real experiments were conducted to verify the simulated analysis, which shows that the proposed method is an alternative for accurately calibrating an on-line wavelength. In addition, the proposed method is able to suppress noises in the process of wavelength calibration, which gives it an advantage in accurate on-line wavelength calibration with a low SNR.

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ON-LINE WAVELENGTH CALIBRATION OF PULSED LASER FOR CO₂ DIFFERENTIAL ABSORPTION LIDAR

Xiang

¹

,

Ma

²

,

Han

³

et al. 2016

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

0

View full text Add to dashboard Cite

Commission I, WG I/2KEY WORDS: On-line wavelength calibration, Pulsed laser, Multi-wavelength scanning, Energy matching ABSTRACT:Differential absorption lidar (DIAL) remote sensing is a promising technology for atmospheric CO 2 detection. However, stringent wavelength accuracy and stability are required in DIAL system. Accurate on-line wavelength calibration is a crucial procedure for retrieving atmospheric CO 2 concentration using the DIAL, particularly when pulsed lasers are adopted in the system. Large fluctuations in the intensities of a pulsed laser pose a great challenge for accurate on-line wavelength calibration. In this paper, a wavelength calibration strategy based on multiwavelength scanning (MWS) was proposed for accurate on-line wavelength calibration of a pulsed laser for CO 2 detection. The MWS conducted segmented sampling across the CO 2 absorption line with appropriate number of points and range of widths by using a tunable laser. Complete absorption line of CO 2 can be obtained through a curve fitting. Then, the on-line wavelength can be easily found at the peak of the absorption line. Furthermore, another algorithm called the energy matching was introduced in the MWS to eliminate the backlash error of tunable lasers during the process of on-line wavelength calibration. Finally, a series of tests was conducted to elevate the calibration precision of MWS. Analysis of tests demonstrated that the MWS proposed in this paper could calibrate the on-line wavelength of pulsed laser accurately and steadily.

show abstract

A Method Toeliminate the Backlash Error of Tunable Laser

Cited by 3 publications

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ON-LINE WAVELENGTH CALIBRATION OF PULSED LASER FOR CO<sub>2</sub> DIFFERENTIAL ABSORPTION LIDAR

ON-LINE WAVELENGTH CALIBRATION OF PULSED LASER FOR CO<sub>2</sub> DIFFERENTIAL ABSORPTION LIDAR

Wavelet modulus maxima method for on-line wavelength location of pulsed lidar in CO_2 differential absorption lidar detection

ON-LINE WAVELENGTH CALIBRATION OF PULSED LASER FOR CO₂ DIFFERENTIAL ABSORPTION LIDAR

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A Method Toeliminate the Backlash Error of Tunable Laser

Cited by 3 publications

References 0 publications

ON-LINE WAVELENGTH CALIBRATION OF PULSED LASER FOR CO&lt;sub&gt;2&lt;/sub&gt; DIFFERENTIAL ABSORPTION LIDAR

ON-LINE WAVELENGTH CALIBRATION OF PULSED LASER FOR CO&lt;sub&gt;2&lt;/sub&gt; DIFFERENTIAL ABSORPTION LIDAR

Wavelet modulus maxima method for on-line wavelength location of pulsed lidar in CO_2 differential absorption lidar detection

ON-LINE WAVELENGTH CALIBRATION OF PULSED LASER FOR CO2 DIFFERENTIAL ABSORPTION LIDAR

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ON-LINE WAVELENGTH CALIBRATION OF PULSED LASER FOR CO<sub>2</sub> DIFFERENTIAL ABSORPTION LIDAR

ON-LINE WAVELENGTH CALIBRATION OF PULSED LASER FOR CO<sub>2</sub> DIFFERENTIAL ABSORPTION LIDAR

ON-LINE WAVELENGTH CALIBRATION OF PULSED LASER FOR CO₂ DIFFERENTIAL ABSORPTION LIDAR