$sound diffraction clear gas$

$sound diffraction clear gas$

#SOUND DIFFRACTION CLEAR GAS FREE#

In this case, we can concentrate the diffracted beam entirely in the 1st order diffraction with almost zero intensity for 0th and −1st order beams 17. In addition, due to this large optical depth, the device can be used as a volume refractive grating to obtain asymmetric diffraction. In this scheme, the modulation amplitude is almost 100% so that we achieve more than a half-wavelength optical path difference with 1 cm thickness of the medium. Instead, we describe here a method to create large density modulations in a neutral gas. Some ideas to increase the optical path length were previously proposed 16. This low value is one of the main barriers to creating a real optical device with neutral gas medium. However, the typical refractive index of neutral gas is only 10 −4 or 10 −5 above unity. To achieve gas-phase diffraction optics, a spatial density modulation of the gas is used. 15), which is two orders of magnitude higher than the operating laser energy flux of conventional solid-state optics. The damage threshold of a gas medium for nanosecond lasers is normally >1 kJ/cm 2 (ref. To solve these problems, we propose an alternative approach to transient diffraction optics using neutral gas with a linear absorption process. The laser power required to produce the index modulation or change in the optics is quite large and sometimes even larger than the power of the diffracted laser beams. This large energy deposition causes a high-energy density condition in the plasma optics and results in a short lifetime.

#SOUND DIFFRACTION CLEAR GAS FREE#

However, the energy needed to produce free electrons is typically several or tens of electronvolts per atom. This number is similar to the conventional optical coating. When a high-density plasma is created in the interaction of an intense pulse laser with a gas or solid surface, the obtainable refractive index change is around 10 −1–10 −3. Normally, these electrons are generated with nonlinear optical interactions. In general, plasma optics use the polarizability of free electrons to modulate the refractive index. To date, plasma gratings 9, 10, 11, 12, 13 and plasma mirrors 14 have been proposed and some are already installed in real laser systems. One candidate is plasma transient optics. This situation can be improved if transient optics are introduced. A typical reduction factor for practical use is from 2 to 10 (ref. Recently, a method for optical damage management idea has been employed, but the usable intensity is not dramatically increased. Once optical damage occurs in conventional solid optics, the damaged spot does not recover and it is not easy to replace the optics in a large-size optics laser system. Due to the probabilistic aspect of the optical damage, the actual useful fluence in the high repetition laser is much smaller than the singe-pulse damage limit. Recently, laser average power has increased significantly and laser pulse repetition rates have grown from 10 Hz to 10 kHz and more. Even well below the nominal optical damage threshold, the damage-risk is not zero. Optical damage is a serious problem not only for energetic giant laser systems but also for high repetition rate lasers. These small values are the main reason why high-energy lasers need meter-size optics. The damage threshold for structured optics such as a grating is lower than for flat mirrors and typical damage thresholds are 0.1–12 J/cm 2 (refs. For the visible and near-infrared region, typical values are 1–200 J/cm 2 for a nanosecond pulse laser 5. The damage threshold of dielectric coated mirrors depends on the pulse duration and laser wavelength. Despite such rapid growth of the output energy, the damage threshold of optical elements has not increased at a similar rate. The output energy of laser pulses has increased from 100 mJ to 2 MJ 4 during the last 50 years. These include new fusion energy sources 1, new acceleration methods for charged particle beams 2, and intense extreme ultraviolet (EUV) sources for semiconductor manufacturing 3. High-energy lasers are opening up new research fields. Since the conception of lasers, a great deal of effort has been invested in order to increase laser power and energy.

$sound diffraction clear gas$

Sound diffraction clear gas