Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/35—Non-linear optics
  • G02F1/3525—Optical damage
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
  • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
  • G02B26/0875—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more refracting elements
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/35—Non-linear optics
  • G02F1/37—Non-linear optics for second-harmonic generation

Definitions

• the present invention relates to a device for extending the life of one or more linear or non-linear optical components subjected to the radiation of an intense laser beam.
• the invention finds applications in particular in optical frequency converters and in particular harmonic optical generators comprising a nonlinear crystal, this crystal being subjected to potentially destructive radiation such as intense and focused UV radiation.
• the invention is also applicable to parametric optical oscillator (OPO) laser sources tunable in frequency.
• OPO parametric optical oscillator
• Solid state lasers are known to produce beams of excellent optical quality and are used in many applications, including micro-machining of semiconductors, marking of plastics, etching of solar cells ... For a large part of these applications it is necessary to convert the generally infrared radiation emitted by the laser into radiation at higher frequencies.
• Pulse solid lasers can produce average powers exceeding 100 watts on pulses of relatively short duration (less than 200 ns).
• laser media such as Nd: YVO4, Nd: YAG, Nd: YLF as well as Nd or Yb doped glass fibers as a laser pulse source that can operate at a very high rate (typically 10 to 500 kHz).
• the production of the third harmonic is now commercial and powers of the order of 2OW have been obtained at 355 nm, from 4W to 266 nm and a growing interest for even shorter wavelengths appears.
• the major difficulty that arises when one wants to produce the harmonics of a laser pulsed at high speed comes from the lifetime of optical components subjected to high power in the UV.
• the classical method consists in focusing an intense beam in a nonlinear crystal.
• the typical crystals are LBO, BBO or CLBO but any other crystal could do the trick.
• the low energy per pulse forces to focus the beam on diameters of the order of 100 microns.
• the power density then reaches several tens of kW per cm 2 and ends up inducing unacceptable defects.
• a known method for limiting crystal degradation is to move the non-linear crystal in a plane transverse to the axis of the laser beam after a period of hours to weeks to find a new area of the crystal that does not still suffered damage.
• the size of the beam being of the order of 100 microns and that of the crystal of typically 3x3 mm, it is easy to decompose the surface of the crystal in more than a hundred elementary zones that the beam will illuminate one after the other during these trips. If we consider that the beam can remain 10Oh on an area without losing more than 10% of its power for example, the life of the crystal is increased by a factor of 100 to reach about 10 00Oh. When all zones have been progressively used, the crystal must be changed. Such a method is described in US Pat. No.
• a nonlinear optical system is understood to mean a set of optical components comprising at least one nonlinear optical component, which may be a nonlinear crystal.
• US Pat. No. 5,546,764 describes a device for continuously rotating the beam of a laser in a circular trajectory on the surface of a crystal in order to avoid local heating of the crystal.
• the device comprises two identical blades with flat and parallel faces, the two blades being arranged on either side of a nonlinear optical frequency conversion crystal.
• the two blades are symmetrically inclined at a fixed angle relative to the axis of the laser beam, and rotated continuously about the axis of the beam.
• This device makes it possible to move quickly (several hertz) in a circle the point of impact of the beam, the crystal remaining fixed.
• the rotation of the two blades must be identical and synchronized to maintain a first approximation of a fixed direction output beam.
• the size of the UV laser beam is of the order of 100 microns.
• This UV laser beam is generally coupled to optics to be precisely focused. The direction and the position of the beam must be kept within a few percent, that is to say within a few microns.
• the object of the present invention is to overcome these drawbacks and more particularly concerns a device for extending the service life of at least one non-linear optical frequency converter system subjected to the radiation of an intense laser beam, the optical system being able to convert a fundamental optical frequency incident beam ⁇ 1 into an optical frequency output beam Co 2 .
• the device comprises a first transmission plate with flat and parallel faces, of thickness e 2 and index n 2 ( ⁇ 1 ) capable of being inserted in the optical path of said incident laser beam and transmitting a beam , the normal ⁇ 2 to a plane face of said first blade forming an inclination angle (Z 2 ) with the propagation axis X of the laser beam.
• the device comprises a second transmission plate with flat and parallel faces, of thickness e 3 and index n 3 ( ⁇ 2 ) capable of being inserted into the optical path of the beam at the output of said optical system and transmitting a beam of optical frequency ⁇ 2 , the normal ⁇ 3 to said second blade forming an inclination angle (Z 3 ) with respect to the axis of propagation X 'of the beam.
• the device of the invention further comprises a means of transverse rotation of said first blade around at least one axis (Y, Z) transverse to the axis of propagation (X) of the laser beam capable of modifying the inclination ( Z 2 ) over an angular range (i 2 0 ⁇ ⁇ i 2 ) for moving the beam relative to the optical system and means for transverse rotation of said second blade about at least one axis (Y ', T) transverse to the propagation axis (X ') of the beam capable of modifying the inclination (Z 3 ) over an angular range (Z 3 0 ⁇ ⁇ i 3 ).
• the two blades and the transverse rotation means of the two blades are capable of minimizing the amplitude of displacement in position and in angular direction of the output beam over the angular inclination range (i 2 0 ⁇ ⁇ i 2 ) of the first blade.
• the device comprises means of mechanical coupling of the two blades adapted to make integral the inclination (Z 2 ) of the first blade and the inclination (Z 3 ) of the second blade over the angular range (i 2 0 ⁇ ⁇ i 2 ) and the thickness e 3 of the 2 nd ⁇ blade is adapted to minimize the amplitude of the residual displacement of the beam of output as a function of the thickness e 2 of the 1 ⁇ r ⁇ lamina, the optical indices n 2 ( ⁇ - ⁇ ) and n 3 (c 2) and the angular range (i 2 ° ⁇ ⁇ i 2 ).
• the coupling means of the two blades comprise a mechanical drive means adapted to cause the simultaneous inclination of the two blades with respective inclination angles Z 2 and Z 3 opposite.
• the coupling means of the two blades comprise a mechanical drive means adapted to cause the simultaneous inclination of the two blades with angles of inclinations respectively Z 2 and Z 3 equal.
• the rotation means is common to the two blades and able to modify the inclination of the two blades by an identical angle and the incident beam and the output beam propagate in a plane between the two blades and the output beam undergoes an odd number of reflections between the blades.
• the diameter of the incident beam on the optical system is less than the amplitude of displacement of the beam induced by the inclination of the first blade on the angular inclination range (i 2 ° ⁇ ⁇ i 2 ).
• the two blades are identical and the device comprises means capable of calculating and applying an angle of inclination (Z 3 ) as a function of the thickness of the blades, their optical indices n 2 ( ⁇ - ⁇ ) and n 3 ( ⁇ 2 ) and the angle of inclination (Z 2 ) so as to compensate for the displacement of the output beam for each angle of inclination of the 1 ⁇ r ⁇ blade over the angular range (i 2 ° ⁇ ⁇ i 2 ).
• the device of the invention comprises an optical system having an optical magnification G placed between the two blades and the angle of inclination (Z 3 ), the thickness (e 3 ), and the index (n 3 ). of the 2 nd ⁇ blade are determined according to the magnification G of said optical system so as to compensate for the displacement of the output beam for each inclination (Z 2 ) over the angular range (i 2 ° ⁇ ⁇ i 2 ).
• the invention also relates to a nonlinear optical source comprising a nonlinear optical system and a device for extending the lifetime of said nonlinear optical system according to one of the preceding embodiments, the blades of which are arranged on either side. another of said nonlinear optical system.
• the nonlinear optical source of the invention comprises a nonlinear optical system comprising two nonlinear crystals situated between the two blades of the device for extending the life of said crystals, the first nonlinear crystal being capable of doubling the frequency of the incident fundamental wave and the second nonlinear crystal being capable of generating the harmonic 3 ⁇ m ⁇ by a sum of frequencies between the fundamental wave and its second harmonic.
• the nonlinear optical source of the invention comprises a nonlinear optical system comprising two nonlinear crystals located between the two blades, the first nonlinear crystal being able to double the frequency of the incident fundamental wave. and the second non-linear crystal being capable of generating 4 harmonic ⁇ m ⁇ by doubling the frequency of the second harmonic.
• the nonlinear optical source of the invention comprises a nonlinear optical system comprising three nonlinear crystals located between the two blades, the first nonlinear crystal being able to double the frequency of the fundamental wave. incident, the second nonlinear crystal being adapted to the generation of 3 harmonic ⁇ m ⁇ by mixing the frequency of the second harmonic and the fundamental wave, and the third nonlinear crystal being suitable for the generation of the harmonic ⁇ m ⁇ by mixing of frequency of the second harmonic and the third harmonic produced by the first and second crystals.
• the invention also relates to a nonlinear optical source comprising at least one crystal located between the two blades capable of producing a coherent radiation by optical parametric generation.
• the invention also relates to a nonlinear optical source comprising means for measuring the transmitted power of the beam after frequency conversion and a drive system capable of driving the transverse rotation of the blades when the transmitted power decreases by a predefined value.
• the invention also relates to a nonlinear optical source comprising a device for extending the lifetime of a nonlinear optical system placed inside a laser cavity.
• the present invention also relates to the features which will emerge in the course of the description which follows and which will have to be considered individually or in all their technically possible combinations.
• FIG. 1 represents a block diagram of a device of the invention
• FIG. 3 diagrammatically represents a generator of harmonic 2 nd ⁇ according to the prior art
• FIG. 4 schematically represents a harmonic 2 nd ⁇ generator according to the invention
• FIG. 5A schematically represents the operation of a system with two blades inclined on either side of a non-linear crystal at a first inclination of the two blades, and FIG. 5B according to a second inclination of the two blades;
• FIG. 6 represents a curve for measuring the compensation error of the output beam as a function over an angular inclination range (i 2 0 ⁇ Si 2 );
• FIG. 7 represents a harmonic 3 ⁇ m ⁇ generator according to the prior art;
• FIG. 8 shows a first embodiment of generator 3 ⁇ m ⁇ harmonic according to the invention
• FIG. 9 represents a second embodiment of a generator of 3 harmonic ⁇ m ⁇ according to the invention.
• - Figure 10 shows schematically a control system of the orientations of the blades in a device of the invention;
• FIG. 1 schematically shows a mechanical coupling means of the two blades of a device of the invention
• FIG. 12 represents an example of scanning of the illumination zone by the laser beam using a device of the invention.
• FIG. 1 schematically represents the operating principle of a device for extending the lifetime of a nonlinear optical system according to the invention.
• a non-linear optical system 19 is located on the propagation axis of an optical beam 7, for example a laser beam.
• the nonlinear optical system is in the considered principle example consisting of a nonlinear optical component 1.
• the optical component 1 receives an incident optical beam 7 of fundamental optical frequency ⁇ 1 propagating along an axis X and transmitting an optical beam output 17 of optical frequency ⁇ 2 propagating along an axis X '.
• the device comprises two blades 2 and 3 with flat and parallel faces of respective thicknesses e 2 , e 3 .
• Both blades are placed in the optical path of the optical beam.
• the first blade 2 is placed in the path of the incident beam 7 and inclined at an angle i 2 with respect to the axis X.
• the angle of inclination i 2 is the angle formed between the normal ⁇ 2 at the surface of the blade 2 and the axis of the beam 7.
• the incident beam 7 passes through the blade 2 and leaves in a transmitted beam 27 of optical frequency ⁇ -i.
• the transmitted beam 27 propagates along an axis parallel to the axis of propagation of the incident beam 7.
• the second plate 3 is placed in the path of the optical frequency beam 17 ⁇ 2 at the output of the optical component 1 and inclined at an angle i 3 with respect to the axis X '.
• the angle of inclination i 3 is the angle formed between the normal ⁇ 3 at the surface of the blade 3 and the axis of the bundle 17.
• the inclination of each blade 2, respectively 3 can be modified by transverse rotations around two axes (Y, Z) respectively (Y ', Z) perpendicular to the axis of propagation X respectively X' of the laser beam.
• the inclination i 2 of the blade 2 is variable over an angular range (i 2 ° ⁇ ⁇ i 2 ) by one or two rotations transverse to the axis X.
• the inclination i 3 of the blade 3 is variable on an angular range (Z 3 0 ⁇ Si 3 ) by one or two rotations transverse to the axis X '.
• the amplitude of the angular variations of i 2 is ⁇ 10 deg.
• the blades 2 and 3 do not rotate axially around the axis of the beam.
• the modification of the inclination i 2 of the first blade 2 induces a displacement (d Y2 , d Z2 ) of the beam 27 transmitted by said blade 2 on the optical component 1.
• This displacement (d Y2 , d Z2 ) makes it possible to modify the zone of the optical element subjected to the optical radiation of the incident beam.
• the second blade 3 makes it possible to better compensate for the lateral offset (d Y2 , d2 ) of the axis of the beam 17 at the output of the optical component 1 over a range of inclination of the blades 2, 3 and to maintain the fixed position.
• propagation axis of the laser beam 37 at the output of the device by adjusting the respective inclinations of the two blades 2 and 3 and / or by optimizing the thickness of the two blades.
• FIG. 2 indicates in more detail the propagation of the laser beam in a plate 2 or 3.
• FIG. 2 represents a projection in a plane comprising the X axis of propagation of the incident beam and the normal ⁇ at a blade with flat and parallel faces.
• a flat and parallel-faced plate of thickness e is inserted on the axis of the incident optical beam 7 in front of the optical component 1.
• the inclination of this plate at an angle / with respect to the axis of the beam 7 induces a deviation of the axis of the beam 27 at the outlet of the blade, which propagates along an axis offset by an amount d.
• the crossing of a plate of thickness e and index n whose normal angle is / with the beam induces a displacement of the beam of a distance d given by:
• the adjustment of the angle / is obtained by the combination of two rotations 0 ⁇ , ⁇ z around two directions (Y, Z) transverse to the axis of propagation X, which makes it possible to deviate the beam at the output of the following blade two directions (d ⁇ ; dz) transverse to the axis of propagation of the beam. It is thus possible to modify the lighting zone of the beam on the optical component 1 over a wide area relative to the size of the beam.
• the axis of the beam 27 emerging from the blade 2 is in construction perfectly parallel to the axis of the input beam 7 regardless of the inclination / blade. A maladjustment of the blade 2 in translation or in rotation can by construction introduce only a translation of the output beam but in no case a variation of its direction.
• Figure 2 shows a deflection of the beam in a plane.
• the deflection can also occur in another direction perpendicular to the axis of propagation.
• the output beam can be made perfectly collinear with the input beam by adding a second blade 3 whose thickness and orientation are optimized to compensate for the offset induced by the first blade 2.
• Offset compensation of the output beam is much more difficult to obtain when the wavelengths are different and the inclination of the blades is variable.
• the output beam generally does not have a constant position depending on a variable inclination.
• the repositioning error of the output beam depends on both the inclination angles of the two blades and the input and output wavelengths. An object of the invention is to minimize this repositioning error for a range of angular variation of inclination of the blades.
• the optical index n of a blade varies as a function of the wavelength due to the dispersion.
• the offset d depends both on the physical properties of the blade (its thickness e, its index n) of its inclination / and the wavelength of the beam passing through it.
• the invention uses these various parameters to obtain the best possible compensation between two blades 2 and 3 over a predefined range of transverse rotations of the blades, that is to say over a range of angles of inclination i 2 ,
• the invention can be used for many applications and will be explained in different special cases that are the production of the second harmonic and the production of the third harmonic of a laser beam.
• a conventional 2 nd ⁇ harmonic generation scheme is shown in FIG. 3.
• a laser source 4 produces source radiation at a frequency ⁇ generally located in the near infrared.
• the source 4 comprises a first nonlinear crystal (not shown) which converts the source radiation to the frequency 2 ⁇ located in the visible.
• the source 4 thus emits a visible radiation 7 directed towards an optical focusing means 5 which is in general a lens.
• the optical means 5 may also be a mirror or a set of mirrors and / or lenses.
• the lens 5 focuses the beam 7 at a point on a nonlinear crystal 1.
• the nonlinear crystal 1 is adapted to the frequency doubling of the beam 7 and generates a beam 17 at the frequency 4 ⁇ .
• An optical system comprising a collimating lens 6 and one or several dichroic mirrors 10 and 1 1 makes it possible to separate the beam 7 at the frequency 2 ⁇ of the beam 17 at the frequency 4 ⁇ .
• the crystal 1 is generally mounted on a displacement system that makes it possible to change the point of impact of the beam 7 on the nonlinear crystal when the conversion efficiency towards the 4 ⁇ m ⁇ harmonic drop.
• two blades 2 and 3 are inserted between the optical means 5, 6 and the crystal 1.
• the non-linear crystal 1 remains fixed and therefore does not require a displacement system.
• the blade 2 is interposed between the lens 5 and the crystal 1 and the blade 3 between the crystal 1 and the lens 6.
• the blades 2 and 3 are adjustable with a variable inclination around two Y axes, Z perpendicular to the laser beam.
• the blades 2, 3 have an antireflection treatment at the wavelengths of use.
• FIG. 5 schematically represents the effect of displacement of the beams on the crystal 1 and at the output of the device produced by a pair of blades 2, 3 inclined on a focused laser beam for different orientations of the pair of blades, respectively represented in FIG. 5A and 5B.
• the blades 2, 3 induce a shift of the optical axes.
• the first blade 2 used alone makes it possible to obtain the effect of displacement of the point of impact of the transmitted beam 27 on the crystal 1, but the position and the direction of the output beam 37 change with the variation of inclination of this blade. 2, which is generally not acceptable.
• the thickness of the second blade 3 and / or its inclination i 3 are optimized to better compensate for the displacement of the first blade 2 over a range of inclinations of the blades.
• the beam 17 which interests us at the output of the nonlinear crystal 1 does not have the same wavelength as the incident beam 27 on this crystal 1. It is therefore necessary to take into account in the calculation of the orientation of blades 2 and 3.
• the formula [I] shows that the offset d depends on the angle of incidence i but also on the index n which varies with the length of wave.
• the offset can be compensated by using two identical blades (same thickness and same material) but oriented with slightly different angles to compensate for the index difference or to use orientations of the same magnitude but of sign opposite with blades of different physical thicknesses calculated so that the optical thickness of the wavelength beam 2 of the blade 2 corresponds to the optical thickness of the wavelength beam 3 of the blade 17.
• this compensation is valid only for constant angles of inclination i 2 and i 3 , and for the wavelengths ⁇ 1 of input and Go 2 of output also fixed.
• FIG. 6 shows an example of the result of the repositioning error made using a 26 mm blade 2 of index 1, 45 at 515 nm and a blade 3 of the same material at 243 nm.
• optimization can be achieved by various conventional methods of minimizing error.
• we can apply the least squares method which amounts to minimizing the distance between the two curves d 2 (i) and d 3 (i). Mathematically this amounts to looking for a set of values of n 3 and e 3 which minimizes the quantity: i
• a second particular implementation of the invention concerns the production of the third harmonic.
• a conventional device for generating 3 harmonic ⁇ m ⁇ is shown schematically in Figure 7.
• a laser source 4 ' is used to produce radiation at the frequency ⁇ generally located in the near infrared.
• the infrared radiation of the laser is focused by optical means 18 on a first nonlinear crystal 1 which converts the radiation to the frequency 2 ⁇ .
• This conversion is not complete, the system then emits a beam comprising both a radiation 7 at the frequency ⁇ and a radiation 17 at the frequency 2 ⁇ .
• These confused beams 7 at ⁇ and 17 at 2 ⁇ are incident on an optical focusing means which is in general a lens 5.
• the lens 5 focuses the two beams 7, 17 at a single point on a second non-linear crystal 16.
• the second Non-linear crystal 16 is adapted to allow the frequency summation of the beams 7 and 17 to produce a beam 47 at the frequency 3 ⁇ .
• An optical system comprising a focusing lens 6 and one or more dichroic mirrors 10 and 1 1 makes it possible to separate the beams 7 and 17 at the frequencies ⁇ and 2 ⁇ respectively of the beam 47 at the frequency 3 ⁇ .
• the orientation of the crystal 1 is chosen so that the "walk-off" direction of the beams 7 and 17 in the crystal 1 is opposite to the walk-off direction of these same beams in the crystal 16 .
• the temperature of the crystals 1 and 16 is stabilized with an accuracy of the order of 0.1 ° C.
• the crystal 16 is generally mounted on a displacement system which makes it possible to change the point d impact of the beams 7 and 17 when the conversion efficiency to the 3 harmonic ⁇ m ⁇ drops, the optical beams 7, 17 and 47 remaining fixed.
• the two blades 2 and 3 are inserted between the optical means 5, 6 and the crystal 16.
• the blade 2 is interposed between the lens 5 and the crystal 16 and the blade 3 between the crystal 16 and the lens 6.
• the blades 2, 3 are adjustable with an inclination i 2 , respectively i 3 variable over an angular range of inclinations by transverse rotations around two Y axes, Z perpendicular to the laser beam.
• the non-linear crystal 16 remains fixed and does not require a displacement system.
• the blades 2, 3 have an antireflection treatment at the wavelengths of use.
• a limitation of the device presented in FIG. 8 comes from the chromatism of the offset introduced by the plate 2. Indeed, the two beams 7 and 47 are not at the same wavelength, and will thus undergo very slightly different offsets that may possibly affect the generation of the 3 ⁇ m ⁇ harmonic.
• the blade 2 is placed in front of the first doubling crystal 1.
• the direction and the amplitude of the movement of the blade 3 must then take into account the magnification introduced by the lens 5 as well as the difference in wavelength between the beams 7 and 47.
• This control of the variation of inclination of the blade 3 can be carried out using an electronic system capable of calculating the orientation of the beam. blade 3 to compensate for the displacement induced by the blade 2.
• the device can be simplified by omitting the lens 5. In this case the size of the beams in the crystals 1 and 16 is approximately equal.
• FIG 10 shows a layout diagram of the device in a simplified embodiment.
• An electronic control system 13 controls the orientation variations of the blades 2 and 3.
• the control system ensures that the respective orientations i 2 , Î 3 blades 2, 3 are perfectly identical but opposite.
• the control system calculates the orientation correction of the blade 3 with respect to the orientation of the blade 2, for each inclination i 2 of the blade 2.
• the thickness of the blades 2 and 3 is calculated so as to minimize the compensation error by taking into account the difference in index seen by the radiations 7 and 47 by using the relation [I] over the range of variation of the angles d inclination of i 2 and i 3 .
• the size of the beams in crystals 1 and 16 is approximately equal. It may be advantageous to have a different beam size in both crystals.
• To do this we introduce an optical system having a magnification G between the crystals 1 and 16. In this case we must take into account the optical system in the calculation of the compensation by the blade 3 of the displacement introduced by the blade 2.
• the sign of magnification between the crystals 1 and 16 is positive. In the case where there is an optical conjugation between the two crystals and where we want to use the simplified mode of compensation to a single mechanism simultaneously moving the plate 2 and 3 the number of reflections to be introduced on the optical path between the blade 2 and the blade 3 must always be odd.
• the systems presented in connection with FIGS. 7 to 11 correspond to the particular case of the third harmonic generation, but they also apply in other cases requiring a variation over time of the position of the beam on an optical element.
• the same device also applies to optical frequency converters, including Optical Parametric Oscillators (or OPOs), which make it possible to produce tunable light sources in wavelength ( ⁇ 2 variable).
• the amplitude of the rotation of the blade 2 (that is to say the range of inclinations i 2 ° ⁇ ⁇ i 2 ) is calculated to introduce a displacement d 2 corresponding to approximately 3 times the diameter of the blade. beam on the crystal.
• the inclination variations of the blades are preferentially discontinuous between two periods of use of the device, the beam remaining fixed between two displacements.
• Transverse rotation of the slides is typically applied every 100 to 500 hours.
• the formula [I] makes it possible to determine the value of the amplitude of this rotation as a function of the absolute value of the angle of inclination. Different strategies of scanning movements of the beam on the crystal can be used.
• the blade may for example be rotated progressively about a horizontal axis until the beam reaches the edge of the crystal.
• the blade is then turned a small angle along the vertical axis and can be reversed in the horizontal axis.
• the movement of the beam in a plane transverse to its axis of propagation then follows a scanning trajectory as shown in FIG. 12.
• the device of the invention makes it possible to locally move a laser beam with respect to an optical component in two independent directions transverse to the axis of the beam, while maintaining the direction of the transmitted beam parallel to the incident direction and the position of the beam in output of the fixed device. Only the beam inside the device thus moves with respect to a fixed nonlinear optical system while guaranteeing a perfect orientation of the laser beam with respect to the optical system whatever its position and ensuring the perfect repositioning (in angle and in position) of the laser beam at the output of the device.
• the nonlinear optical system may be a nonlinear crystal, a group of nonlinear crystals, a set of non-linear optical components or any combination comprising the aforesaid elements.

Landscapes

• Physics & Mathematics (AREA)
• Nonlinear Science (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
• Lasers (AREA)
• Mechanical Light Control Or Optical Switches (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=40809829

Family Applications (1)

Country Status (6)

Cited By (1)

Families Citing this family (19)

Citations (4)

Family Cites Families (15)

• 2008
  • 2008-11-21 FR FR0857915A patent/FR2938935B1/fr not_active Expired - Fee Related
• 2009
  • 2009-11-20 JP JP2011536931A patent/JP5898957B2/ja not_active Expired - Fee Related
  • 2009-11-20 EP EP09795476A patent/EP2359186B1/fr not_active Not-in-force
  • 2009-11-20 US US13/130,307 patent/US8885246B2/en not_active Expired - Fee Related
  • 2009-11-20 CN CN200980154936.7A patent/CN102292671B/zh not_active Expired - Fee Related
  • 2009-11-20 WO PCT/FR2009/052234 patent/WO2010058136A1/fr active Application Filing

Patent Citations (4)

Also Published As

Similar Documents

Legal Events