Current Technology of Beam Profile Measurements

Kirkham, Kevin; Roundy, Carlos B.

doi:10.1201/9780824741631.ch9

Cited by 16 publications

(19 citation statements)

References 12 publications

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“…DART has improved lidar modeling in realistic acquisition geometry and power distribution. For an emitted laser pulse, two Gaussian profiles are defined: the temporal convolution of the transmitted pulse and receiver response function, S(t) =Ŝe − t 2 2s 2 s ; and the 2-D power profile P l (β) within the footprint cone such that the ratio of P l (β t ) at the boundary (half-divergence β t ) to the central maximumP l,β can be 0.5 (i.e., full width at half maximum (FWHM)), 1/e 2 , or 1/e [60]. The distribution follows: P l (β) =P l,β e − β 2 2s 2 β , where β represents the angular offset from the pulse direction and s β is the standard deviation of the angular divergence.…”

Section: Lidar Pulsementioning

confidence: 99%

Modeling Small-Footprint Airborne Lidar-Derived Estimates of Gap Probability and Leaf Area Index

Yin

Cook

et al. 2019

Remote Sensing

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Airborne lidar point clouds of vegetation capture the 3-D distribution of its scattering elements, including leaves, branches, and ground features. Assessing the contribution from vegetation to the lidar point clouds requires an understanding of the physical interactions between the emitted laser pulses and their targets. Most of the current methods to estimate the gap probability (P gap ) or leaf area index (LAI) from small-footprint airborne laser scan (ALS) point clouds rely on either point-number-based (PNB) or intensity-based (IB) approaches, with additional empirical correlations with field measurements. However, site-specific parameterizations can limit the application of certain methods to other landscapes. The universality evaluation of these methods requires a physically based radiative transfer model that accounts for various lidar instrument specifications and environmental conditions. We conducted an extensive study to compare these approaches for various 3-D forest scenes using a point-cloud simulator developed for the latest version of the discrete anisotropic radiative transfer (DART) model. We investigated a range of variables for possible lidar point intensity, including radiometric quantities derived from Gaussian Decomposition (GD), such as the peak amplitude, standard deviation, integral of Gaussian profiles, and reflectance. The results disclosed that the PNB methods fail to capture the exact P gap as footprint size increases. By contrast, we verified that physical methods using lidar point intensity defined by either the distance-weighted integral of Gaussian profiles or reflectance can estimate P gap and LAI with higher accuracy and reliability. Additionally, the removal of certain additional empirical correlation coefficients is feasible. Routine use of small-footprint point-cloud radiometric measures to estimate P gap and the LAI potentially confirms a departure from previous empirical studies, but this depends on additional parameters from lidar instrument vendors.

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Section: Lidar Pulsementioning

confidence: 99%

Modeling Small-Footprint Airborne Lidar-Derived Estimates of Gap Probability and Leaf Area Index

Yin

Cook

et al. 2019

Remote Sensing

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“…Also the propagation of the beam through space is significantly affected on the beam profile [12] . We calculated M 2 , or the factor k= 1/M 2 [13] , which is important in describing the quality of laser beam in many applications, especially those in which a Gaussian beam is the desired profile.…”

Section: Materials and Methodologymentioning

confidence: 99%

The modern use of optics design techniques to production visual Art works

Ahmedien¹

2012

IOSRJHSS

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“…Some industrial laser applications require periodic beam profile monitoring to eliminate scrap produced when the laser degrades. In other applications, such as some medical uses of laser, the practitioner has no capability to tune the laser, and the manufacturers measure the beam profile in design to ensure that the laser provides reliable performance at all times [1]. In general, the analysis of laser beam is based on energy measurement, the intensity distribution of the laser beam, beam divergence, waist parameter, number of modes …, etc.…”

Section: Introductionmentioning

confidence: 99%

Design and Construct A beam Profile of Near IR Laser Based on CCD Camera

Al-Ani¹,

Ahmed²,

Yousif³

2012

JNUS

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One of many applications of Lasers is the beam profile. For some Lasers and applications this may only be necessary during the design and fabrication phase of the Laser. The aim of the research is to design and construct a Laser beam profile based on CCD camera. The system have been constructed on analyzing in the near infrared (NIR) Laser beams as the CCD silicon chip can be exploited in this region of the electromagnetic spectrum. The results show the successfulness of the profile in displaying proper Laser images. Also, care must be taken to avoid over exposing the CCD camera. Finally, stability of the imaging system is of great important.

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Current Technology of Beam Profile Measurements

Cited by 16 publications

References 12 publications

Modeling Small-Footprint Airborne Lidar-Derived Estimates of Gap Probability and Leaf Area Index

Modeling Small-Footprint Airborne Lidar-Derived Estimates of Gap Probability and Leaf Area Index

The modern use of optics design techniques to production visual Art works

Design and Construct A beam Profile of Near IR Laser Based on CCD Camera

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