Optical metrology devices for high-power laser large optics

Daurios, Jérôme; Bouillet, Stéphane; Gaborit, Gael; Poncetta, Jean-Christophe

doi:10.1117/12.726071

Cited by 8 publications

(7 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Even if our laboratory disposes of a high performance photometer [9], it is not suited for scattering components. Indeed, the measured transmission may change regarding to the solid angle of the detector.…”

Section: Photometry -Energy Lossmentioning

confidence: 99%

“…Many experiments cannot stand too significant energy in the "wings" (outside the disk) so their intensity levels has to be controlled. Our laboratory being equipped with a wide and complete set of instruments for large optical component measurements [9], we measured the wavefront distortion introduced by the CPP with a Fizeau interferometer. We were then able to calculate the diffracted focal spot profile with the Caustix software (CEA software).…”

Section: Continuous Phase Plates Qualificationmentioning

confidence: 99%

See 1 more Smart Citation

Measuring a laser focal spot on a large intensity range: effect of optical component laser damages on the focal spot

et al. 2009

View full text Add to dashboard Cite

LIL and LMJ are two French high power lasers dedicated to fusion and plasma experiments. Mastering the characteristics of the focal spots focused on the targets during the experiments is very important. In order to analyze the focal spots in its high power lasers, the CEA has developed an independent set-up that enables to measure energy spatial profiles over a 5 decade dynamic range by the means of several acquisitions taken at different power levels. The different data sets are then stitched to obtain a high dynamic picture of the beam. The experiment can also be used as a photometer enabling to measure the energy transmitted by an optical component. We used this set-up to study the effect of different parameters on the energy spatial profile of the focal spots. We have measured the effect of laser damages (on the optical components of the beam) on the energy scattered around the main focal spot. We also demonstrated that the level of this scattered power can be calculated from a near-field picture of the beam or even with pictures of the damaged components taken with an appropriate lighting.

show abstract

Section: Photometry -Energy Lossmentioning

confidence: 99%

Section: Continuous Phase Plates Qualificationmentioning

confidence: 99%

Measuring a laser focal spot on a large intensity range: effect of optical component laser damages on the focal spot

et al. 2009

View full text Add to dashboard Cite

show abstract

“…In this section, the sets of parameters are sorted with regard to characterization difficulty. Therefore, we first consider the outer radius of the defect only, which can be characterized by photography [30] (Sec. III A).…”

Section: Impact Of Partial Parameter Knowledgementioning

confidence: 99%

Strong Light Intensifications Yielded by Arbitrary Defects: Fresnel Diffraction Theory Applied to a Set of Opaque Disks

et al. 2019

Self Cite

View full text Add to dashboard Cite

Two centuries ago, Fresnel, Poisson, and Arago showed how the wave nature of light induces a bright spot behind an opaque disk. We develop an analytical model based on the Fresnel diffraction theory to show how small perturbations such as digs or scratches can yield intense light enhancements on the downstream axis. The impact of defects with complex morphology on light diffraction is shown to be accurately modeled by the Fresnel theory applied to a set of opaque disks characterized by phase shift and transmittance. This model can be used either to define the geometry of the defects that optimizes the light enhancement or to improve the defect specification on the surface of the optical components. We explain why partial information of the defect morphology can suffice to specify a safety distance beyond which light intensifications are not dangerous. The validity of this analytical approach is studied by measuring the intensifications created by three different microdefects.

show abstract

“…Generally speaking all those optical components are specified regarding their wavefront performance [4] among various other specifications. The Optical Metrology Laboratory (LMO) at CEA is equipped with several instruments to control those specifications [5]. Nevertheless, interferometric testing can be uneasy to achieve for specific components such as multi-dielectric mirrors or gratings because one has to use the exact nominal configuration (wavelength, incidence, geometry of the incident beam) to perform a correct measurement.…”

Section: Introductionmentioning

confidence: 99%

Wavefront measurements through optical diffraction interpretation

et al. 2013

View full text Add to dashboard Cite

The French Laser MégaJoule (LMJ) will include 176 square beams involving hundreds of large optical components. Wavefront performances of all these components are critical to achieve the desired focal spot shape and to limit hot spots that could damage the components. These specifications are usually checked with interferometric setups. This can be uneasy to achieve for specific components such as multi-dielectric mirrors or gratings because one has to use the exact nominal configuration (wavelength, incidence, geometry of the incident beam) to perform the measurement. For the smallest spatial periods, classical techniques like interferometric microscopes fail to measure the wavefront and propose a "surface" measurement that can lead to misinterpretations. We present in this paper measurement methods based on a laser beam diffraction interpretation that can efficiently replace the usual techniques. The first technique consists in measuring intensity level of the dim scattered "corona" around the focal spot. The second one is based upon image processing of near-field acquisitions by the means of Fourier analysis and the Talbot effect theory. Those techniques do not lead to a phase map as classical techniques do but they give access to the Power Spectral Density of wavefront defects over a large spatial frequency bandwidth. For many applications, this is enough information to estimate the component performance. We present results obtained by this way on LMJ components and a comparison with Fizeau interferometer measurement.

show abstract

Optical metrology devices for high-power laser large optics

Cited by 8 publications

References 0 publications

Measuring a laser focal spot on a large intensity range: effect of optical component laser damages on the focal spot

Measuring a laser focal spot on a large intensity range: effect of optical component laser damages on the focal spot

Strong Light Intensifications Yielded by Arbitrary Defects: Fresnel Diffraction Theory Applied to a Set of Opaque Disks

Wavefront measurements through optical diffraction interpretation

Contact Info

Product

Resources

About