Surface damage growth mitigation on KDP/DKDP optics using single-crystal diamond micro-machining ball end mill contouring

Geraghty, Paul B.; Carr, W.; Draggoo, Vaughn G.; Hackel, Richard P.; Mailhiot, C.; Norton, Mary A.

doi:10.1117/12.696076

Cited by 26 publications

(21 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1,24,25 Therefore, the LIDTs in this work were measured following a deterministic R-on-1 protocol, in which the laser irradiates each test site with increasingly ramped energy until damage occurs. 7,18,34 The damage fluence is defined as the lowest laser fluence at which damage occurs. A total of 10 sites are involved in each test and the LIDT is determined as the average damage fluence.…”

Section: -3mentioning

confidence: 99%

Determination of ultra-short laser induced damage threshold of KH2PO4 crystal: Numerical calculation and experimental verification

et al. 2016

View full text Add to dashboard Cite

Rapid growth and ultra-precision machining of large-size KDP (KH2PO4) crystals with high laser damage resistance are tough challenges in the development of large laser systems. It is of high interest and practical significance to have theoretical models for scientists and manufacturers to determine the laser-induced damage threshold (LIDT) of actually prepared KDP optics. Here, we numerically and experimentally investigate the laser-induced damage on KDP crystals in ultra-short pulse laser regime. On basis of the rate equation for free electron generation, a model dedicated to predicting the LIDT is developed by considering the synergistic effect of photoionization, impact ionization and decay of electrons. Laser damage tests are performed to measure the single-pulse LIDT with several testing protocols. The testing results combined with previously reported experimental data agree well with those calculated by the model. By taking the light intensification into consideration, the model is successfully applied to quantitatively evaluate the effect of surface flaws inevitably introduced in the preparation processes on the laser damage resistance of KDP crystals. This work can not only contribute to further understanding of the laser damage mechanisms of optical materials, but also provide available models for evaluating the laser damage resistance of exquisitely prepared optical components used in high power laser systems.

show abstract

Section: -3mentioning

confidence: 99%

Determination of ultra-short laser induced damage threshold of KH2PO4 crystal: Numerical calculation and experimental verification

et al. 2016

View full text Add to dashboard Cite

show abstract

“…As is well known, KDP crystal is one of the most difficult optical materials to be fabricated due to the unique properties (extremely soft, fragile, deliquescent and easy to craze), and the defects repairing is a meaningful way to prolong the life of optical components and improve its optical performance. Although several machining methods have been reported to repair the micro-defects on the surface of KDP crystal, which include CO 2 laser processing, femtosecond laser ablation, washed etching and micro machining, micro-milling has been reported as a most promising approach by Lawrence Livermore National Laboratory [5,6].…”

Section: Introductionmentioning

confidence: 99%

The design and optimization of micro polycrystalline diamond ball end mill for repairing micro-defects on the surface of KDP crystal

Chen

et al. 2016

Precision Engineering

View full text Add to dashboard Cite

“…One of the strategies is to first initiate the damage precursors at fluencies below the operational fluence and then replace the initiated damage sites with a pre-designed benign mitigation structure [5] with a much higher damage threshold. These mitigation structures can be created by multiple techniques including femtosecond laser machining, single crystal high-speed diamond machining, and magnetorheological finishing [5][6][7]. In fact, our earlier study of creating rationally designed features utilizing femtosecond laser machining [5] has shown an increase in the laser damage threshold, from 15 J/cm 2 to 40 J/cm 2 for light at 1064 nm, with a 3ns pulse length.…”

Section: Introductionmentioning

confidence: 99%

Searching for optimal mitigation geometries for laser-resistant multilayer high-reflector coatings

et al. 2011

View full text Add to dashboard Cite

Growing laser damage sites on multilayer high reflector coatings can limit mirror performance.One of the strategies to improve laser damage resistance is to replace the growing damage sites with pre-designed benign mitigation structures. By mitigating the weakest site on the optic, the large aperture mirror will have a laser resistance comparable to the intrinsic value of the multilayer coating. To determine the optimal mitigation geometry, the finite difference time domain method (FDTD) was used to quantify the electric-field intensification within the multilayer, at the presence of different conical pits. We find that the field intensification induced by the mitigation pit is strongly dependent on the polarization and the angle of incidence (AOI) of the incoming wave. Therefore the optimal mitigation conical pit geometry is application specific. Furthermore, our simulation also illustrates an alternative means to achieve an optimal 2 mitigation structure by matching the cone angle of the structure with the AOI of the incoming wave, except for the p-polarization wave at a range of incident angles between 30 and 45 .

show abstract

Surface damage growth mitigation on KDP/DKDP optics using single-crystal diamond micro-machining ball end mill contouring

Cited by 26 publications

References 0 publications

Determination of ultra-short laser induced damage threshold of KH2PO4 crystal: Numerical calculation and experimental verification

Determination of ultra-short laser induced damage threshold of KH2PO4 crystal: Numerical calculation and experimental verification

The design and optimization of micro polycrystalline diamond ball end mill for repairing micro-defects on the surface of KDP crystal

Searching for optimal mitigation geometries for laser-resistant multilayer high-reflector coatings

Contact Info

Product

Resources

About