The technique for measuring wave front distortions in optical elements by the shadow method is developed. Shadow pictures obtained for mutually perpendicular orientations of the Foucault knife-edge are the distributions of components of the gradient of the function describing the wave front relief, so that its shape can be restored by means of integration. An example of measurements of wave front distortions in large-scale optical KDP crystal elements employing the IAB 451 device is given.
We have experimentally demonstrated the existence of super-broadband non-degenerated phase matching for a signal with a wavelength of 911 nm in KD*P crystal pumped with wavelength of 527nm. Parametric amplification coefficient of more than 10<sup>7</sup> in three cascades is achieved. This resulted in pulse energy 10mJ at the output of third cascade. It is shown that in the KD*P crystal chirped pulses of conventional femtosecond sources (a Ti:Sa laser at 911 nm and a Cr:forsterite laser at 1250 nm) can be amplified up to the level that ensures multipetawatt power after compression.
Optical elements made of KDP, DKDP crystals are up to now among the most expensive and significant ones in high-power laser systems with frequency conversion into higher harmonics. Only some companies have mastered such production technology of optical elements with the aperture size up to 40 by 40 cm. The production is characterized by very long cycles of crystal growth and large waste at manufacturing optical elements, which leads to an extremely high price of the products. An alternative technology based on rapid technology of profiled growth of crystal products and the technology of optical diamond micromilling by means of ISM- 600 machines are developed now at the Institute of Applied Physics RAS. The cycle duration of the crystal product growth reduces tens times, cutting of te grown product into optical elements proves to be practically wasteless. This leads to reduction of product growth reduces tens times, cutting of the grown product into optical elements proves to be practically wasteless. This leads to reduction of product cost and significant shortening of product cycle duration. The quality of crystal growth and optical processing is consistent with the requirements of optical systems. This together with the described applied technologies has permitted to manufacture optical elements for a series of high-power lasers.
Problems of creating high-efficiency technology of crystal KDP, DKDP blanks production for high-power lasers using the elaborated laboratory rapid-growth technology are considered. The laboratory technology enables one to grow crystal samples of the sizes and quality close to the requirements of the ICF laser drivers. The improved technology will provide samples completely satisfying the ICF demands. It is expected that the productivity of the developed technology will exceed the traditional one by an order, while the cost of samples will be essentially lower than in other technologies.
Principal parameters of KH<SUB>2(1-x</SUB>)D<SUB>2x</SUB>PO<SUB>4</SUB>: the optical absorption and the refractive indices dispersion in a wide range, important for frequency conversion of iodine laser radiation are investigated. The use of 'skew' FC elements is proposed. Tuning curves have been calculated for 'normal' and 'skew' FC elements. The doubling and tripling 'skew' FC elements are used in large iodine laser installations: 'Iskra-IV' (Russia) and 'Perun' (Czech).
The two types of high rate growth technology of KDP-type crystal are observed. This technology will be used for effective producing of crystal elements for high-energy laser systems. The recent achievements (in particular the obtaining of 380 by 230 by 50 mm Z-plate from KDP crystal) are reported.
The problem of creating highly effective technology to fabricate crystal elements for high- energy laser systems is observed. The principal technology is developed which permits us to grow crystal blanks with given shapes, dimensions, and orientations. The growth rates exceed the conventional ones by more than 10 times. The (101) orientation KDP crystal with dimensions 380 by 450 by 50 mm has been obtained. The possibility of use 'skewed' elements is considered.