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Intensity distribution of the X-ray beam redirected through a conventional monolithic poly-capillary quasi-parallel lens is similar to a Gaussian distribution, which will bring about unsatisfactory imaging quality for medical applications and affect the peak-to-background ratio in X-ray diffraction experiments. These disadvantages can be overcome by adopting poly-capillary X-ray lenses structured with three tiers that fabricated from different diameters of capillaries. This paper developed a mathematical model of monolithic poly-capillary quasi-parallel lens composed with different diameter tubes, and experimental data of intensity distribution, transmission efficiency and divergence have been compared with simulation results based on a ray-tracing technique.

Ellipsoidal monocapillary x-ray optics are used as condenser lenses in full-field transmission x-ray microscopy. The numerical aperture (NA) of the ellipsoidal monocapillary is designed to match that of the x-ray zone plate objective. In practice, monocapillaries have inner-surface errors that lead to mismatches between the monocapillary and the zone plate. In this study, mathematical models of monocapillaries with elliptic cross-section deformation and centreline straightness errors were developed, respectively. Furthermore, the optical properties of these monocapillaries were simulated based on a ray-tracing method. The simulation provides a qualitative picture of the NA and illumination angle distributions of the ellipsoidal monocapillary with inner-surface errors, and it is useful for predicting the inner-surface imperfections from the x-ray ring behind the monocapillary.

A folded resonator of vertical cavity surface-emitting (VCSE) stripe array of diode lasers is presented. The upper surfaces of VCSELs (vertical cavity surface emitting lasers) are anti-reflected, and the lower surfaces are Bragg mirrors. A strip plane-convex mirror and the Bragg mirrors are applied to form the folded resonator. This strip plane have some transparent partitions. Every VCSEL is connected by the axis of the resonator, and this axis is formed by linking the correspondent reflective points on the inner spherical surface of the mirror and the reflective points on the Bragg mirrors. One approach could be to fabricate the array directly on a plane of a GaAs (or Si) plano-convex mirror. The resonator is also a spatial filter, and can contain many VCSELs, and therefore can afford a high quality laser beam and high-power output.

Three-dimensional (3D) confocal x-ray fluorescence analysis technology is widely used, but the quantitative analysis of elemental spatial distributions of solid samples is complicated. This paper explores a quantitative analysis method that can be applied to solid samples. Fluorescence spectra of liquid samples are obtained on a 3D confocal x-ray fluorescence spectrometer. Curves are plotted showing the relationships between the fluorescence count intensity and the mass percentage of metal ions, and the respective fitting-curve equations are determined according to the curve morphology. Fluorescence intensity as a function of the mass percentage and depth position is derived from the samples for a particular acquisition time. These data play a potential role in the subsequent quantitative analysis of unknown mass percentages of solid samples.

The properties of standard Laguerre–Gaussian beam (sLGB) and elegant Laguerre–Gaussian beam (eLGB) through the misaligned complex hard edge apertures (MCHEAs) are investigated. Analytical formulae for the far field distributions of sLGBs and eLGBs through the different hard edge apertures are derived based on the generalized Huygens–Fresnel diffraction integral equation. The propagation properties and beam qualities of sLGBs and eLGBs are studied comparatively. It is shown that the divergence angle of sLGBs with the low order modes is less than that of eLGBs. However, the energy distributions of eLGBs with the high order modes after through the multiple hard edged apertures are more convergent in comparison with sLGBs, and eLGBs have the better beam quality than sLGBs. The study results are useful for the propagations and applications of sLGBs and eLGBs through the complex optical systems.

Using misalignment matrix of optical components, the change law of the single-pass diffraction loss with the discharge tube and resonator mirror misalignment of two-dimensional axisymmetric-fold combination cavity CO 2 laser are researched and analyzed. The change curves with misalignment angle are also calculated and simulated numerically in this paper. The results show that when the laser parameters are ascertained, the single-pass diffraction loss is less than 0.1, the misalignment angle range of discharge tube and resonator mirror are obtained, and it is beneficial to the adoption of resonator and instruction for installation.

Despite better reconstruction quality for incomplete or noisy projection data compared to analytic reconstruction, computed tomography iterative techniques are time-consuming, mainly due to high system matrix computation. A polar-coordinate pixel model with concentric annuluses of different radial widths was established and a fast method for computing the system matrix was presented based on characteristics of this model. Compared with the Siddon algorithm and an efficient Cartesian algorithm introduced by Zhang, the proposed algorithm based on the simultaneous algebraic reconstruction technique shows speed advantages for both numerical simulation and experiment, without noticeable loss of image quality.

Non-tradition-employed (NTE) lenses are presented. The characters are proved by the experiment. Multilayer reflection coatings on designated zones on the surfaces of the lens are different in reflectivity(R) because of different NTE aims. Incident light beams paraxially bounce back and forth between two surfaces of the lens, then leave from a zone or multiple zones of the lens. The application schemes involve solid-state multiple-pass cell, combination of light beams or laser beams, and phase-locking of a laser array.

The line deviations and angle deviations of the injected beam at the resonator mirrors in the large area discharge CO2 laser (LADCL) are changed when the output mirror and the phase-locking mirror (PLM) are misaligned. The equiphase surfaces excited by the injected beam are different in the laser resonator and the effect of phase-locking will be influenced. It is shown that the misalignment of PLM is the main cause of phase-locking range reduction. The misalignment of the output mirror will mainly result in the deviation of the output beam, and the misalignment of the PLM will mainly cause decrease of the light intensity. And the maximum misaligned angle should not exceed 20 s in order to obtain the ideal effect of phase-locking. The calculated results can provide references for studying deeply the misalignment of LADCL.

A new stripe-shaped lens laser scheme is proposed. The Nd 3 + : g l a s s concave-convex lens with a diameter of 110 mm and thickness of 10 mm is processed, which the curvature radius of concave surface is 10,000 mm and the curvature radius of convex surface is 9800 mm. The reflectivity at the rest of the two surfaces is 99.9%, except that the transmission is 15% at the central circular area of the concave having a diameter of 8 mm to 1.06 µm light wave. The stripe-shaped area of the lens is pumped with a pulsed Xenon flashlamp which the diameter is 8 mm, and the energy of 521 mJ single transverse mode at 1.06 µm laser is obtained from the central regions of the concave surface, and the feasibility of the lens laser scheme is verified.

A new type of axisymmetric-fold-combination CO2 laser, which is constituted by several axisymmetric four-mirror cavities, is studied theoretically in this paper. The mutual energy coupling occurring within the communal discharge region of the unstable resonator to inject seed signals into each sub-resonator is demonstrated by theoretical deduction. The numerical results have proved that phase-locking could be achieved in this cavity, and the beams with phase-locking have both a higher intensity and a smaller light spot than the ones without phase-locking.

In order to study the thermal optical effect (TOE) resulting from the axisymmetrical sources of thermal energy at the output mirror of CO2 laser, the Heat Conduction Poisson Equation (HCPE) has been solved in the output mirror. Then the temperature distribution is given. The temperature variations will cause the surface distortion and the phase shift at the output mirror. Therefore, the output laser beam will be subject to thermal optical distortion and phase change. The numerical examples are to confirm our calculated results.

The influences of misalignments of an axisymmetrical folded-combined (ASFC) CO2 laser on the output power are studied in detail. The new cavity axes are established by using the misaligned matrixes corresponding to the misalignments of the output mirror and the discharge tube, and the diffraction losses of the cavity and the output powers are calculated. It is shown that the influences of the misalignments on the output power are significant when the misalignment angle of the output mirror exceeds 20 s. These calculated values afford references for the design of ASFC CO2 lasers.

A method of reflection-injection phase-locking used on two-dimensional axisymmetric-fold combination resonator (ASFC) CO2 laser has been proposed. The structure characteristics and the method of phase-locking have been introduced. The expression of output light intensity distribution has been deduced by matrix theory and Collins Formula and the output light intensity distribution has been numerically calculated and simulated. Comparing the output light intensity distribution in the case of phase-locking with that of non-phase-locking. The result shows that this method of phase-locking greatly improve the characteristics of output beam.

Based on the phase-locking principle of Gaussian beam, the phase-locking mechanisms of the spherical wave from axisymmetric concentric cavity (ASCC) CO2 laser are analyzed. And then we study the variety laws of the equiphase surfaces and the light spots of the injected beam. The numerical calculations show that the injected beam could be considered as a spherical wave approximately in the ASCC. The phase-locking of the spherical wave is different from the phase-locking of the Gaussian beam; there are different field distributions between Gaussian beam and spherical wave. And the phase-locking method could improve the maximum value of the light intensity, the encircled energy reflects the degree of phase-locking.

First, the kinetic investigation of UF 6 + HCl reaction and the isotopic selectivity under CO laser irradiation is performed. On this investigation, the kinetics of UF 6 + HCl reaction by using an intracativity CO laser and CO 2 laser irradiation system, and the isotopic selectivity for this process are studied theoretically. It is found that under the resonant CO laser and CO 2 laser irradiations, the laser-catalyzed reaction rate can increase, and a good selectivity can be achieved. The uranium isotope separation factors β calculated are about 2.44 ∼ 4.05 at laser intensity 50 ∼ 100 W cm −2 and temperature 235 K.

The frequency modulation of the two-dimensional (2D) axisymmetrical folded and combined (ASFC) CO2 laser is performed by a blazed grating. Its principle of phase-locking is studied in detail. The properties of the injected mode in ASFC and the mode coupling coefficient, which are analyzed, will be considered to be the main factors of the phase-locking. It is shown that the effect of phase-locking will not be influenced when the blazed grating is adjusted. However, it will influence the distribution of the light intensity to some degree.

A theoretical analysis of phase-locking in a multi-channel radial array CO 2 laser is presented. The concepts are based on the theories of injection phase-locking and matrix optics. The mutual optical coupling occurring within the central region is demonstrated by theoretical deduction. Interrelated graphs of the coupling coefficient and the distance between the coupling position and the cavity mirror are calculated by numerical simulation. The results of the analysis are in accord with experimental results.

An axisymmetric-fold-combination (ASFC) cavity composed of two planar mirrors and spherical mirrors was designed. It is a stable–unstable resonator cavity. The light field of radial direction is Gaussian distribution. And in angular orientation, the distribution keeps invariant. It could generate annular CO 2 laser beam with excellent spatial coherence. And the spatial coherence is commendably realized with its stable–unstable cavity structure. The output light intensity distribution of this special model was discussed and simulated. With exterior lenses group, the output beams can be adjusted and controlled better to meet the manufactural requirements. Some references were provided for further research of the cavity with cylindrical discharge region.

Based on the propagating theory of the laser beam, the propagating characteristics of the Gaussian beam through an aperture team that comprises two apertures and a convergent lens, are studied. The approximate expressions for the field distribution are derived by the diffracted integral equation in detail under the condition of approximations. In comparison with the approximate expression and the precise expression, we know that there are the approximate same results for the two expressions if the radius of the second aperture is not too large. The numerical examples are given to confirm the correctness of our calculated results.

A laboratory micro X-ray fluorescence spectrometer based on polycapillary X-ray optics (PXRO) was used to carry out the quantitative X-ray fluorescence analysis of single aerosol particles with smaller size than that of focal spot of PXRO. The minimum detection limits measured with the thin-film reference standards were in the range from 13.3 to 0.7 ng cm − 2 when the operating current and voltage were 70 mA and 35 kV, respectively. In order to reduce the effects of the inhomogeneous distributions of the X-ray intensity in the focal spot of the PXRO on the analysis results, the sensitivities were corrected by using a Gaussian function for the quantitative analysis of single aerosol particles. The accuracy of the analysis of single standard solution drops was on average 25% depending on the element and concentration. The precision of the analysis was better than 5%.

The principles of self-phase-locking are introduced under the conditions where the output-mirror is optimally aligned, and the photon degeneracy, root-mean-square (rms) phase error and properties of the equiphase surface of the reflected–injected beam are studied. The influences of misalignment of output-mirror on self-phase-locking are analyzed. The main influences include the overlap of the mode volumes and the energy-coupling coefficient. The fringe visibility and the distributions of the light intensity in the far field are numerically simulated. These results show that there is an angular tolerance within which self-phase-locking still occurs.

Based on the principle of the reflection-injection-locking of the external cavity, the self-phase locking mechanisms of the transversal mode and longitudinal mode are studied, respectively. And the excellent coherent beams are obtained. Unfortunately, the misalignment is inevitable, the new cavity axis is established by the 4×4 augmented matrixes when the holophote is in the misaligned state. The overlapping rate, the energy coupling coefficient and the fluctuation of the equiphase surfaces can be considered the main factors of the influence of the misalignment on self-phase locking. And then the distributions of the light intensity are given by the numerical simulation under the condition of the normal and misaligned states, respectively. The results have shown that the effect of the self-phase locking is excellent when the misaligned angle is in a range of tolerance.

A laser resonator with two annular spherical mirrors is studied. The self-reproducing mode of this resonator is established by means of a self-reproducing ray-cluster. Its existence condition and area are analyzed and provided for the first time. The resonator's adjusting accuracy is analyzed in detail and the relevant calculation for typical cases is illuminated. The tolerance of mirror center displacement from the axis of the coaxial discharge chamber is proved to be about 0–0.15 mm, and the tilt tolerance 0–6″, when resonator length L ≈1 m, the radius of curvature of the two mirrors ρ ≈5–10 L , and the loss of applicable radial width of the coaxial discharge chamber for light propagation is smaller than 1 mm. The object–image relation of the resonator and its application in adjustment of the resonator are also discussed.

Under the condition of ideal phase locking, output beams with excellent coherence from improved axisymmetric-fold-combination (ASFC) CO 2 laser can be obtained. Unfortunately, misalignments are inevitable. The influence of the misalignment of holophote of fold cavity on phase locking is analyzed, and the light intensity distributions are given by numerical simulation. The conclusion is demonstrated that the method of phase locking of the CO 2 laser is fully feasible under the conditions of the ideal and the misaligned. The results have shown that the effect of phase locking is still excellent when the misalignment angle is in the range of tolerance.

Based on transformation matrices in meridian plane and sagittal plane, a geometrical lens design method is presented with the aim of obtaining an improved spot. A concave–convex convergent lens (CCCL) is employed as a shaping lens to focus a group of oblique laser beams from a CO 2 laser with axially symmetrical fold combination (ASFC) resonator. The cases including interference, noninterference, different wavelength, and misalignment have been analyzed. Through theoretical analysis and numerical calculation, a smaller beam radius in a specific reference plane and a smaller far-field divergence angle can be obtained.

Rationality and feasibility of axisymmetric folded-combined cavity CO 2 laser which is reported in this paper have been proved by principle experiments. The laser lays a foundation to manufacture higher power CO 2 lasers whose output power can easily reach 1 kW. Faculas at different positions in free space and facula of nine beams which pass through the beam focusing optics have been obtained. Analyses of the experimental results are made. These analyses lay a foundation for beam transformation, transmission and shaping.

A new type of laser resonator that is designed to extract good phase coherence and circular beams from an annular gain region is developed. We also calculated the parameters theoretically by applying the resonator to a CO 2 laser. And the transfer characteristics of the output beam from the phase-locking laser resonator through a lens are also discussed.

Two new methods for phase-locking are used in the axisymmetrical-fold combination CO 2 laser. We demonstrate the feasibility of two methods by theoretical deduction, and give the light intensity distribution of far field by numerical simulation. When phase is locked, the axisymmetrical-fold combination CO 2 laser can provide a high output power with good beam quality. Furthermore, the peak light intensity of output beam with phase-locking is obviously higher than that without phase-locking.

The far-field anomalous spectral behaviours of a space–time-dependent Gaussian pulsed beam passing through a rectangular aperture are studied. By expanding a hard aperture function into a finite sum of complex Gaussian functions and starting from the Fresnel diffraction integral, the approximate analytical expression for the spectral intensity of a space–time-dependent Gaussian pulsed beam passing through a rectangular aperture is derived. Meanwhile, the corresponding closed-forms for the slit and the unapertured cases are also given as special cases of the general results. The red and blue shifts and the spectral intensity distribution are studied and illustrated with numerical calculations. Specifically, it is shown that the spectral switch takes place when the truncation parameter is equal to particular values or the observation position is at the critical diffraction angle. The possibility of tunable spectral switching in the far field with an apertured pulsed beam by varying the size of the rectangul...

Based on the vectorial Rayleigh diffraction integrals, the analytical expression for the spectral intensity of a vectorial nonparaxial ultrashort pulsed Gaussian beam diffracted at a circular hard-aperture is derived. The effect of f -parameter ( f = 1/ k 0 w 0 ) on the spectral anomalies near phase singularities of the vectorial nonparaxial ultrashort pulsed beams is studied. It is shown that the spectral switch near the phase singularity of diffracted vectorial nonparaxial ultrashort pulsed beam still exists beyond paraxial regime, but disappears when the f -parameter is larger than a certain value.

A new confocal three-dimensional micro X-ray fluorescence (3D micro-XRF) facility based on polycapillary X-ray optics in the detection channel and Kirkpatrick- Baez (KB) mirrors in the excitation channel is designed. The lateral resolution (l(x), l(y)) of this confocal three-dimensional micro-X-ray fluorescence facility is 76.3(1(x)) and 53.4(l(y)) mu m respectively, and its depth resolution d(z) is 77.1 mu m at theta = 90 degrees. A plant sample (twig of B. microphylla) and airborne particles are analyzed. (C) 2007 Elsevier B.V. All rights reserved.

A convective flow CO laser composed of polytetrafluoroethylene discharge tubes, nickel–chromium steel components, a cupric heat exchanger and other components is described. Operating in liquid nitrogen condition, output power of 60 W has been obtained from a non-selective cavity.

This article describes a convective-flow CO laser composed of quartz tubes, nickel–chromium steel components, a copper heat exchanger, polytetrafluoroethylene tubes and other components. The method of vacuum sealing between quartz tubes and nickel–chromium steel pipes by polytetrafluoroethylene tubes enables the laser to operate with liquid nitrogen cooling. An output of 120 W has been obtained by adopting a non-selective cavity.

The experimental proof of the light output on the two-cone axisymmetric-folded combination (ASFC) CO 2 laser has been performed. The output power from the centre discharge tube is 26.7 W, and that of one couple of folded discharge tubes is 40.5 W. Seventeen beams can be obtained from the device, which are from the folded cavities with axes placed in the inner and outer cones, respectively. Therefore, the ASFC CO 2 laser with more discharge tubes can be fabricated and much higher output power can be obtained.

A TE CO 2 infrared emission apparatus with a half cavity is described . Via grating-tune the emissions p(12)–p(28), 00°1–10°0 of CO 2 are obtained for gas mixtures of 15%CO 2 :20% N 2 :65%He and 20%CO 2 :15%N 2 :65%He at a total pressure of 60 kPa ; the output energy and pulse width are 20– 850 mJ and 60– 70 ns , respectively.

Propagation properties of partially coherent elegant Laguerre-Gaussian beam (PC-eLGB) and partially coherent standard Laguerre-Gaussian beam (PC-sLGB) through the turbulent atmosphere are studied. Analytical formulas for the intensity and effective beam width (EBW) of the PC-eLGB and PC-sLGB through the turbulent atmosphere are derived based on the extended Huygens-Fresnel principle. The propagation properties of PC-eLGB and PC-sLGB through the turbulent atmosphere are studied numerically and comparatively. It is shown that the intensities of the PC-eLGB and PC-sLGB are less affected by the turbulent atmosphere than the fully coherent Laguerre-Gaussian beam. The spreading (EBW and divergent angle of the far field) of PC-eLGB and PC-sLGB with the different mode orders (m,n) is slower in the free space than in the turbulent atmosphere, and the PC-sLGB spreads more rapidly than the PC-eLGB through the free space and the turbulent atmosphere. The study results will be useful for free space optical communications.

New-structure polycapillary x-ray optics for high pressure x-ray absorption fine structure (XAFS) absorption spectroscopy using the diamond anvil cells (DAC) method are applied in synchrotron radiation analysis. The optics are composed of a solid glass fiber in the center and surrounded by a hollow glass capillary array. They can restrain the higher harmonic of incident synchrotron radiation and obtain smooth and clear XAFS spectra. At the biological macromolecule station in the Beijing Synchrotron Radiation Facility (BSRF), a method of aligning these optics was developed and the transmission efficiency for both fundamental and higher harmonic waves investigated. The XAFS spectra of topological insulator material of Bi2Se3 were obtained by combining the optics.

A polycapillary x-ray optics is developed for high pressure x-ray absorption fine structure spectroscopy (XAFS). Profiting from a large gain of power density and enlarged divergence of x-ray beams transmitted through the polycapillary, the range of x-ray energies accessible for the measurements is expanded considerably. A contrastive experiment with and without this polycapillary was carried out at the Beijing Synchrotron Radiation Facility (BSRF) high pressure XAFS station (1W1B). The disturbing diffraction peaks from the diamond layer were basically eliminated.

The principle of phase-locking of an axisymmetric fold combination cavity CO2 laser, fulfilled by the reflection–injection of the back surface of the output-mirror, has been studied in detail. Variation of the equiphase surface and the influence of some characteristic parameters on phase-locking are analyzed—for example, phase error, changes in the cavity length and curvature radius, line-width and temperature. It is shown that the injected beam can excite a stable mode in the cavities, and the value of the energy coupling coefficient directly reflects the degree of phase-locking. Therefore, the output beams have a fixed phase relation between each other, and good coherent beams can be obtained by using the phase-locking method.

It has been experimentally demonstrated that a three-dimensional axisymmetric-folded combination carbon dioxide laser with five discharge tubes can offer a desired output power and good-quality light beam. The output laser has five sub-beams that start from a mutual point on the inside surface of the output plane lens. The collimation and convergence of the five sub-beams are obtained. In our results, the measured output laser power from a folded resonator was 37 W, and the total output of the laser was 76 W with 10% efficiency.

Based on the injection-locking principle, the phase-locking mechanisms of axisymmetricfold combination CO2 lasers are analyzed. Then influences of parameters-changes on phase-locking are studied in detail, such as changes of cavity length and curvature radius, linewidth, phase error, and coherence time. It is shown that these factors almost do not influence the degree of mode coupling, but they could influence distribution of light intensity to some degree. Phase-locking can improve the value of maximum light intensity significantly; what is more, the numerical calculation indicates that the higher the fringe visibility the better the coherence.

A CO2 laser with a hollow cone-shaped resonator (HCR) for producing a hollow laser beam (HLB) is proposed. The HCR consists of a totally reflective mirror and a partially reflective mirror at the two ends of a hollow cone-shaped discharge tube. In a longitudinal section of the HCR along its axis of symmetry it can be regarded as a folded cavity. Employing an standard optical system, the HLBs can be focused to meet the requirements of various applications. Analysis shows that not only can an HLB be obtained, but also the radius of the dark region of the focused HLB is easy to adjust. The hollow cone-shaped CO2 laser may be used as a new type of optical tweezers.

We have developed a new type of dual-wavelength transversely excited atmospheric pressure (TEA) CO 2 laser that possesses space overlap and time synchronization. Our experiments have proven that the time interval of two output pulses with different frequencies can be adjusted from 1000 ns to 200 ns. In this way, the requirement of dual-wavelength excitation in a material can be achieved for isotope separation purposes. This TEA CO 2 laser contains a grating-plate cavity formed by one germanium plate and two gratings, where the two gratings partially overlap in the space. The gratings, which are placed in tandem, are mutually beneficial via the germanium plate and establish double-frequency oscillation. The dual-wavelength laser is exported from the germanium plate. It is a changing of the effective area of two gratings that enables us to adjust the space overlap of the two output pulses. By simultaneously adjusting the quantity of misalignment in the gratings angle to vary the spectral line geometry loss, which can be used to reduce the time interval of the two output pulses, a time synchronization can be achieved.

The far-field spectral characteristics of a space-time-dependent Gaussian pulsed beam passing through an annular aperture are studied. Based on the expansion of a hard aperture function into a finite sum of complex Gaussian functions and starting from the Fresnel diffraction integral, some analytical expressions for the spectral distribution of the diffraction field are derived. The expressions for a circular black screen and a circular aperture are given as special cases of the general results. The red and blue shifts of the spectral intensity maximum and the spectral intensity shape distortion and distribution are studied and illustrated with numerical calculations.

The near-field-intensity distributions of diffusion-cooled axisymmetric folded-combined CO 2 lasers are investigated. Formulas representing the near-field distributions for some typical kinds of folded-combined CO 2 lasers are suggested, and the near-field-intensity profiles are calculated numerically and simulated. For several centimeters from the output mirror along the direction of the symmetric axis, the intensity in the output beam is very high and its radius (or width) is very small (approximately double waist radius). The frequency differences between different cavities would induce fluctuations of the intensity distribution, but the fluctuations are not distinctive. The near-field beam can be used directly in some industrial material processing.

We present an axisymmetric-fold combination laser resonator. For a laser with the resonator, it can give a strong output, a good light beam, and a small device volume. The energy flux of the beam is high and the diameter is small in the near field; it diverges with a small angle, but transforming the beam from a divergent beam into a parallel or convergent beam is convenient. The resonator is suitable for various kinds of lasers.

Good quality AgGaSe2 single crystal 22 mm in diameter and 80 mm in length is grown by an improved technique, i.e., descending ampoule with rotation. Although the crystals grow with optical defects, postgrowth heat treatment procedures are used to successfully eliminate the defects and produce material of 62.4% IR transmission at 10.6?m. The frequency-doubling device is cut from a cylindrical crystal boule using a new orientation cut method according to the type-1 phase-matched condition. A high optical quality, orientated AgGaSe2 single crystal of 10x 10x 12 mm size is used for second harmonic generation (SHG) of the pulsed output of a 10.6?m CO2 miniature transversely excited atmospheric laser. A relatively high energy conversion efficiency of 12% is obtained. It is found that the optical surface damage threshold of the crystal is larger than 12 MW/cm2.