Laser induced damage thresholds and laser safety levels. Do the units of measurement matter?

Wood, Roger M.

doi:10.1016/s0030-3992(97)00054-6

Cited by 34 publications

(23 citation statements)

References 1 publication

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“…The distance r i is the outer radius of the damaged area. 21 The relationship of Eq. (4) also applies in the case of the ablation caused by nanosecond pulses.…”

Section: Estimation Of the Damage Threshold Based On Thermal-induced mentioning

confidence: 99%

Laser-induced damage threshold of camera sensors and micro-optoelectromechanical systems

et al. 2017

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, "Laser-induced damage threshold of camera sensors and micro-optoelectromechanical systems," Opt. Eng. 56(3), 034108 (2017), doi: 10.1117/1.OE.56.3.034108. Abstract. The continuous development of laser systems toward more compact and efficient devices constitutes an increasing threat to electro-optical imaging sensors, such as complementary metal-oxide-semiconductors (CMOS) and charge-coupled devices. These types of electronic sensors are used in day-to-day life but also in military or civil security applications. In camera systems dedicated to specific tasks, micro-optoelectromechanical systems, such as a digital micromirror device (DMD), are part of the optical setup. In such systems, the DMD can be located at an intermediate focal plane of the optics and it is also susceptible to laser damage. The goal of our work is to enhance the knowledge of damaging effects on such devices exposed to laser light. The experimental setup for the investigation of laser-induced damage is described in detail. As laser sources, both pulsed lasers and continuous-wave (CW)-lasers are used. The laser-induced damage threshold is determined by the single-shot method by increasing the pulse energy from pulse to pulse or in the case of CW-lasers, by increasing the laser power. Furthermore, we investigate the morphology of laser-induced damage patterns and the dependence of the number of destructive device elements on the laser pulse energy or laser power. In addition to the destruction of single pixels, we observe aftereffects, such as persistent dead columns or rows of pixels in the sensor image.

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“…The distance r i is the outer radius of the damaged area. 21 The relationship of Eq. (4) also applies in the case of the ablation caused by nanosecond pulses.…”

Section: Estimation Of the Damage Threshold Based On Thermal-induced mentioning

confidence: 99%

Laser-induced damage threshold of camera sensors and micro-optoelectromechanical systems

et al. 2017

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“…Equation (4) gives a very nice analytical expression for the diffusion of a Gaussian energy pulse but it is not valid for a CW laser where the pulse duration is long enough that the temperature can diffuse while the laser is still on. In the past, the heat equation (1) has been solved for very long duration pulses (t ¼ 1) and very short pulses ðt ( w 2 =2aÞ, [8][9][10][11][12] whereas we provide a solution for all times. A first simplification is that in a small increment of time, the energy can be replaced with a power multiplied by time.…”

Section: Heat Equation Solution With Heat Generation Termmentioning

confidence: 99%

“…In previous research, there have been seeming anomalies in the temperature distributions seen under CW excitation. 5,6,9 In this paper, a model for high power CW heating of very low absorption mirrors is developed and tested that explains these anomalies.…”

Section: Introductionmentioning

confidence: 99%

High power laser heating of low absorption materials

Olson

Ogloza

Thomas

et al. 2014

Journal of Applied Physics

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A model is presented and confirmed experimentally that explains the anomalous behavior observed in continuous wave (CW) excitation of thermally isolated optics. Distributed Bragg Reflector (DBR) high reflective optical thin film coatings of HfO 2 and SiO 2 were prepared with a very low absorption, about 7 ppm, measured by photothermal common-path interferometry. When illuminated with a 17 kW CW laser for 30 s, the coatings survived peak irradiances of 13 MW/cm 2 , on 500 lm diameter spot cross sections. The temperature profile of the optical surfaces was measured using a calibrated thermal imaging camera for illuminated spot sizes ranging from 500 lm to 5 mm; about the same peak temperatures were recorded regardless of spot size. This phenomenon is explained by solving the heat equation for an optic of finite dimensions and taking into account the non-idealities of the experiment. An analytical result is also derived showing the relationship between millisecond pulse to CW laser operation where (1) the heating is proportional to the laser irradiance (W/m 2 ) for millisecond pulses, (2) the heating is proportional to the beam radius (W/m) for CW, and (3) the heating is proportional to W=m Á tan À1 ð ffi ffi t p =mÞ in the transition region between the two. V C 2014 AIP Publishing LLC.

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“…The laser induced damage is a crucial factor in the application of optical thin film, which is related to the robustness of the whole laser system. The damage mechanisms of optical thin film have been extensively studied by researchers in theory and experiment [2][3][4][5][6] . There are two types of mechanisms in the damage of optical thin film: thermal effect and field effect, which are responsible for the high energy laser induced damage and the high power laser induced damage, respectively [2] .…”

Section: Introductionmentioning

confidence: 99%

“…With the heat accumulating, the optical thin film is likely to fuse and even be totally injured. Because of the very low absorptivity, it needs much high power density (several kW/cm 2 ) continuous wave (cw) laser to cause damage [2,[5][6] . Considering the difficulty in obtaining extremely high power cw laser in the lab, it usually focuses a relatively low power laser beam to achieve such high power density in the experimental study of the thermal damage process [7][8] , as shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Theoretical study of laser induced thermal damage on the narrowband filter optical thin film

Han¹

2015

Proceedings of the 2015 4th International Conference on Computer, Mechatronics, Control and Electronic Engineering

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Abstract. In the experimental study of the film's thermal damage, an extremely high power density is needed. In order to achieve such high power density, the incident beam is generally converted. In this situation, the cone's angle of the converted beam is inevitable. A narrowband filter optical film is taken as an example. The influence of the beam cone angle on the thermal damage of the optical film is theoretically studied. Under the irradiation of high energy laser, the film absorbs the laser energy and the heat is accumulated continuously in the film. The cone's angle influences the laser intensity distribution, i.e. the heat source, in the multilayer film. The temperature distribution and the temperature rising process are also related to the cone's angle. Only if the cone's half angle is smaller than 3°, the influence of the cone's angle can be ignored.

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Laser induced damage thresholds and laser safety levels. Do the units of measurement matter?

Cited by 34 publications

References 1 publication

Laser-induced damage threshold of camera sensors and micro-optoelectromechanical systems

Laser-induced damage threshold of camera sensors and micro-optoelectromechanical systems

High power laser heating of low absorption materials

Theoretical study of laser induced thermal damage on the narrowband filter optical thin film

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