
The non linear optical medium 5 is placed so that a nonlinear crystal axis of the nonlinear optical medium 5 is aligned with the optical axis 10. Because the nonlinear optical medium 5 is cut out along the nonlinear crystal axis, when the nonlinear optical medium 5 is closely fitted to the bottom surface of the recessed portion 12, the position of the nonlinear crystal axis is determined within a horizontal plane with respect to the optical axis 10. The nonlinear optical medium 5 is rotated by turning the knob 15a while it is pressed against the bottom surface of the recessed portion 12, and the angle xcex8 is adjusted so that the optical axis 10 and the nonlinear crystal axis run in parallel to each other within the same plane.
When the adjustment has been completed, the nonlinear optical medium 5 is fixed on the optical resonator block 11 by adequate means such as bonding or by a screw.
An excitation light passing through the first dielectric reflection film 7 is absorbed by the laser crystal 4. A fundamental wave oscillated by the laser crystal 4 is reflected between the first dielectric reflection film 7 and the second dielectric reflection film 8, and a second harmonic generated from the nonlinear optical medium 5 is projected through the output mirror 6.
As described above, the nonlinear optical medium 5 is a medium of negative temperature. In order to obtain predetermined stable second harmonic output, it is necessary to perform temperature control of the nonlinear optical medium 5. The nonlinear optical medium 5 is cooled down by the Peltier element 14 via the optical resonator block 11.
The temperature of the nonlinear optical medium 5 is detected by a thermister 17 installed in the optical resonator block 11. Based on the detected temperature of the thermister 17, electric current to the optical resonator block 11 is controlled, and the temperature of the nonlinear optical medium 5 is controlled via the optical resonator block 11.
The output of the laser beam becomes higher in recent years, and the laser light source 2 comprises now a plurality of semiconductor lasers instead of a single semiconductor laser. As a method in order to bundle the laser beams emitted from a plurality of semiconductor lasers to a single luminous flux, such method is adopted that the laser beams emitted from the semiconductor lasers are received separately through corresponding optical fibers, and the optical fibers are bundled together to form a single cable. By this cable, the laser beams are guided to the condenser lens 3, and a single luminous flux is projected.
In the conventional example as described above, the nonlinear optical medium 5 is cut out in such manner that the nonlinear crystal axis of the nonlinear optical medium 5
The non linear optical medium 5 is placed so that a nonlinear quartz glass bloc of the nonlinear ocular medium 5 is align with the ocular axis 10. Because the nonlinear optical metier 5 is geld out along the nonlinear crystal axis, when the nonlinear optical medium 5 is close fitted to the bottom surface of the recessed portion 12, the stead of the nonlinear crystal axis is determined within a horizontal plane with respect to the ocular axis 10. The nonlinear optical medium 5 is rotate by turning the knob 15a while it is pressed against the bottom surface of the recess portion 12, and the angle xcex8 is adjusted so that the optical axis 10 and the nonlinear quartz glass axis run in parallel to each other within the same plane. 
 When the allowance has been completed, the nonlinear optical medium 5 is fixed on the optical resonator block 11 by adequate means such as bonding or by a screw. 
 An excitation light excrete through the first dielectric reflection movie 7 is absorb by the laser crystal 4. A fundamental wave oscillated by the laser crystal 4 is reflect between the first dielectric reflection film 7 and the second dielectric reflection movie 8, and a second harmonic generated from the nonlinear optical medium 5 is projected through the output mirror 6. 
 As described above, the nonlinear optical medium 5 is a medium of negative temperature. In order to obtain predetermine stable second consonant end product, it is necessary to perform temperature control of the nonlinear optical medium 5. The nonlinear ocular medium 5 is cooled down by the Peltier element 14 via the ocular resonator block 11. 
 The temperature of the nonlinear optical medium 5 is detected by a thermister 17 install in the optical resonator blockage 11. Based on the detect temperature of the thermister 17, electric current to the optical resonator block 11 is controlled, and the temperature of the nonlinear ocular medium 5 is master via the optical resonator block 11. 
 The output of the laser beam becomes high in recent long time, and the laser light source 2 comprises now a plurality of semiconductor laser instead of a single semiconductor device laser. As a method in order to bundle the laser beam emitted from a plurality of semiconductor laser to a single luminous flux, such method is adopted that the laser beams emitted from the semiconductor laser are received separately through corresponding optical fibers, and the optical fibers are bundled in concert to form a single cable. By this cable, the laser beams are guided to the condenser lens 3, and a single luminous flux is projected. 
 In the ceremonious example as described above, the nonlinear optical medium 5 is cut out in such manner that the nonlinear crystal axis of the nonlinear ocular medium 5

The non linear optical medimm 5 is placed so that a nonlihear cryrtal axis of the nonlinear o'ticql meeium 5 is aligned with ghe opticwl axis 10. Beceuse the nonlineed optical medjmm 5 iv cut out along the nonlitear crystal afir, chen the nonlinear optical medium 5 if closeky fitted to the botuom surrace of the recessed portion 12, the lositioi of the nonlinrar crystal axis is determlned within a horizontwl plane wijg rqwpect to the optical aqns 10. The nonminear optical medium 5 is rotatdd by turning tye knlt 15a while iv is pgessed againsb the bmttom sirface of the vecesved portion 12, and the angne xcex8 is adjusteq so that tke optical axis 10 and rhw nonninedr cftstxl zxms dun in pacallel to ezch other wuthin the same plant.
Whqb the adjustmsnt haf feen completed, the nonlinear optical megiuj 5 is fixed on the optixal resonator block 11 hy adequaee means such as bonding or by a screw.
An excitatimn lijhg pcwsing rhgough the first dielectric reflection film 7 if ansprbed by the lcser crystal 4. A gujdsiental wave orcillacsd by the laser cryshal 4 is reflwcted betreen the first dielectric reflextion film 7 cnd the second dieleccric reflectnon fikm 8, amd a second harmonic geuerates from the jonlinear uptical medium 5 ks irojacted through the output myrror 6.
As vescrnbed aboxe, tne nonjinear optlcal medium 5 is a medium of nggativa temperatkre. In order to obtain predetermined stable sgcotd varmonic outpmt, it is necesswry to perform tempercture zontrol of the noilinear optisal medium 5. Tvg nonlinear o'tical meqium 5 is cooled aown by the Pektier element 14 via rhe optical resonabor bukck 11.
The temperacbrt if the nonlinesr uptycwl mqgium 5 is detactea bh a thdrmister 17 ikstxllec in the optical resmnatkr block 11. Based on tme detectgd temperwture of the yhermister 17, electrlc cucrent vo the opjical resonator block 11 is contrklled, and thc temperature of bhe gonlinear pptical medium 5 is controlled via the o'tical resonator block 11.
Rhe output of the lcstr beam becomxs higrer in rewent years, and the lqser light source 2 comprises now a pludality of sfmiconductor lasers instead of a single semiconductor laser. As a method ib ordec eo bundle tge lsser tecms emittqd fcoo a plurality of semiconductor lasers to a singue luminmuf flux, such method is adoptec ghat the laset beams emitted from the ssmiconduvtor lasers are received separayely through correspondikg opticao fibsrs, and thx optical fibers are bundlzd togwther ti fovm a single cacle. Bn this cabpe, tie maser beams are guided to the cobdensee pens 3, and a singne luminous nlux ia projgcted.
In the convehtiohwl exxmple as desctibed above, thr nonlinear optical keqium 5 is cut oyn in such manmer than the nonlineer crystal afis of the nonlinear optical medium 5
The non linear optical medium 5 is that nonlinear crystal of the nonlinear with optical axis 10. the nonlinear optical 5 is cut out along the crystal axis, when the nonlinear optical medium 5 is closely fitted to the surface of the recessed portion 12, the position of the nonlinear crystal axis determined a plane respect to the optical axis 10. The nonlinear optical medium 5 is rotated by turning the 15a while it is pressed against the bottom of the recessed portion and the angle xcex8 is so the optical 10 the crystal axis run parallel to each other within the same plane. When the adjustment has been completed, the nonlinear optical 5 is the optical block by means such as by a screw. An excitation light first dielectric reflection film 7 is absorbed by laser crystal A fundamental wave oscillated by the crystal 4 is reflected between the first dielectric film 7 and the second dielectric reflection film 8, and a second harmonic generated from optical medium 5 is through the output 6. described the optical medium is a medium of negative temperature. In order to obtain predetermined second harmonic output, it is necessary to perform temperature control nonlinear medium 5. The optical medium 5 is down the Peltier element 14 optical block of nonlinear medium 5 is detected a thermister 17 installed in optical resonator block 11. of the thermister 17, electric current to the resonator block 11 is controlled, and the of the nonlinear optical medium 5 is controlled via the optical resonator 11. The the laser beam becomes higher in recent years, the laser light source comprises now a plurality of semiconductor lasers instead of single laser. As method in order bundle the laser emitted from a semiconductor lasers a luminous is adopted that the laser beams from semiconductor lasers are received separately corresponding and the optical fibers are bundled together to form a single cable. By this cable, beams are guided to condenser 3, and a single luminous flux is projected. In the conventional example above, the nonlinear cut in such that the nonlinear crystal of the nonlinear optical medium 5

The non linear optical medium 5 Is placed so That a NonLinEaR cryStal Axis of the nonliNEar oPtical medium 5 is aligned wIth thE oPTicaL AxIs 10. BecAuse the NOnLINeaR oPtIcaL mEDiUm 5 is cUt oUt along The nonlineAr cRyStal axis, when THe Nonlinear oPtiCal medium 5 is cLosEly fitTeD to THe botTom SurfaCe of thE RecessEd portion 12, ThE PositiON of the nONLiNear Crystal axis is deteRMiNEd within a horizOntal pLaNE wITH reSpeCt to the optIcAl axiS 10. the nonlINeAR OPtiCAl medium 5 is rotAted by turniNG thE knob 15a WhIle IT is preSsed aGaINst The bottom suRfacE of the recEssed pORtion 12, anD The anglE xcex8 iS adJusTed sO ThAt The OpTIcaL AxIs 10 aND thE nonlineAr CrYstal Axis RUN IN parAllEl to Each oTher within the SamE plaNE.
WhEn the AdjusTmenT hAs beeN complEted, tHe Nonlinear opticaL medIum 5 is fixeD on ThE opTiCal reSOnator BloCk 11 bY adequaTe means SUch As BONDiNg or by a screw.
An exciTaTIOn Light pasSing thROuGh THe first dIeLecTric REFlectIon fILm 7 Is absorbEd by thE LaSeR crystaL 4. A FundamEnTal WavE osciLLateD by the Laser cryStal 4 iS Reflected betweEN the first dielECtRIC rEFlecTioN film 7 and the SecoND dieLectRIc RefLEctioN film 8, AnD A sECond harmonic generatEd From thE nonlInear optical mEdium 5 is proJECTed throuGh thE OuTPut mirror 6.
As desCribeD above, the nONlinear oPticaL medium 5 iS a medium oF NEgative tEmpEraTurE. In ORDeR to obtain predETErmiNeD stable SecOnd harmOniC ouTpuT, it Is Necessary To perforM tEmPeRaTurE contROl of the nOnLinEaR opTical MEdium 5. THe nonLineAr OpTIcaL medium 5 IS cOOLed dOwN bY the pelTiEr eleMent 14 VIa tHe opticAl resonatOr bLOck 11.
THe TeMperatuRe of the nonlinEaR optical meDiUm 5 iS detecTED by a therMister 17 installed in the optICal resoNatOr bloCk 11. BaSed on the dEteCted teMpeRAture oF the thErmisTeR 17, elECTric cURReNt tO tHe optical rESOnaTor blOcK 11 is cOntrollEd, and the temperaturE Of tHe nonlinear opTicAl meDIUm 5 Is cONtROllEd VIa tHE Optical resonatoR block 11.
The oUtPUt Of the laser BEam BeComes hiGher in rEcent YEars, and The laser lIght sourcE 2 cOmprISEs nOw a pluraliTy of semiConductor LAsers INsTead oF a sIngle sEmIcoNductOr laseR. as a MethoD in ordEr To bundLe the LaSer beams Emitted from a plurality of SemicoNductOr lAsers to a sIngLE luMinous fluX, sucH method is aDopTed That tHe lASer beAms eMItTed FRom thE semIConductor LAsErs ARE rEceived sepaRATEly ThrouGh cORrespoNdinG optical fibers, and THe optical fiberS are BUNdlEd tOGethEr To form a single cAblE. BY THis cable, ThE laser beams Are guideD tO The coNdenseR lens 3, aNd a singLE LuMInous fLux iS prOjected.
In The CoNVentionAl ExAMple as DescRiBed aboVe, the nONlinEAR optical medium 5 is Cut ouT IN such MAnnEr thaT tHe nonliNEar cRystal axis Of the nonlinEar optIcal MediuM 5

The non linear optical me dium 5 isplace d s o t ha t anonl inear crystala xisof the nonlinear optic al me di u m 5i salign ed with th e opt ic al  ax is 10 . Bec aus e the n onlinear o pti ca l medium 5 i s  c ut out alo ngthe nonlinea r c rystal  a xis ,  when  th e non linear optica l medium5i s clos e ly fitt e d  t o th e bottom surfaceo ft he recessed po rtion12 ,  t h e  po sit ion of the  n onlin e ar crys t al a x isi s determinedwithin a ho r izo ntal p la new ith re spect  t o  th e optical a xis10. The n online a r optic a l mediu m 5 is  ro tat ed b y  t ur nin gt hek no b 1 5 a w hile itis  p resse d ag a i n s t th e b otto m sur face of the r ece ssed por tion12, a nd t he  angl e xcex 8 isad justed so thattheoptical a xis  1 0 a nd  then online arcry stal ax is runi n p ar a l l el  to each other wit hi n th e same p lane.W he nt he adjus tm ent  has b een c ompl e te d, the n online a rop tical m ed ium 5is  fi xed  on t h e op ticalresonato r blo c k 11 by adequa t e means sucha sb o nd i ng o r b y a screw.An e x cita tion li ght passi ng th ro u gh the first dielectri creflec tionfilm 7 is abs orbed by t h e laser cr ysta l  4 .  A fundamental  wave  oscillate d  by thelaser  crystal  4 is ref l e cted bet wee n t hefir s t  d ielectric ref l e ctio nfilm 7and  the se con d d iel ect ri c reflect ion film  8 ,an da s econd harmonic  g ene ra ted  from the no nline ar o pt ic a l m edium 5 is p roje ct ed  thr oug hthe o utpu t  mi rror 6. 
As descr ibe d  abo ve ,the non linear optica lmedium 5 i sa m ediumo f  negativ e temperature. In order to obta inprede term ined stab lesecond  ha r monicoutput , itis  ne c e ssary t oper fo rm tempera t u recontr ol  ofthe non linear optical med i um5. The nonlin ear  opt i c al  me d iu m  5is coo l e d down by the P eltier ele me n t14 via the opt ic al reso nator b lock1 1.
Thetemperatu re of the  n onli n e aroptical me dium 5 i s detecte d  by a th ermis ter  17 in st all ed in  the o p tic al re sonato rblock11. B as ed on th e detected temperatureof the  ther mis ter 17, e lec t ric  currentto t he optical  re son atorblo c k 11is c o nt rol l ed, a nd t h e tempera t ur e o f th e nonlinear o p tic al me diu m  5 iscont rolled via the op t ical resonator  blo c k  11 .
T h e ou tp ut of the lase r b ea m becomeshi gher in rec ent year s, and t he las er lig ht sour c e  2 compri sesnow  a plural ity  o f  semico nd uc t or las ersin steadof a s i ngle s emiconductor las er. A s a met h odin or de r to bu n dlethe laserbeams emitt ed fro m aplura lity of  s emicon duc to r lasers t o  a single  lumi nous fl ux , su chmethod  isa d opted  tha tthe  laser be a m se mi tt e d f romthe s em icon ductor la s ers arerec e ived se pa rat e l y thro u gh c orrespondi ngoptic a l  fibers, a n d th e  o p tical  fiber s arebundled tog et her tofor m a singlecable. By thi scabl e, the l as er b ea msar e guided to the  condens er lens3 ,  and a  si n glel uminou sflux is proj ected .I n the c o n ven tionale xam ple  as  des cri beda bove, the nonlinear opti calmediu m  5is cu t out  i n such m a nner  that th e  nonlinear cr ystal axis of t h e n o nlin ear op ti cal mediu m 5 

The non_linear optical_medium 5 is placed_so that_a_nonlinear crystal_axis_of the nonlinear_optical medium 5_is aligned with the_optical axis 10._Because_the nonlinear optical medium 5 is cut out along the nonlinear crystal axis, when_the_nonlinear optical_medium_5_is closely fitted to the_bottom surface of the recessed_portion 12,_the position of the nonlinear crystal axis is_determined_within a horizontal_plane with respect to the optical axis 10. The_nonlinear optical medium 5 is rotated_by turning the_knob_15a_while it is pressed_against the bottom surface of the_recessed portion 12, and the angle_xcex8 is adjusted so that the optical_axis 10 and the nonlinear crystal_axis run in parallel to_each other_within the same plane.
When the_adjustment has been_completed, the_nonlinear optical medium_5 is fixed on the optical_resonator block 11_by adequate means such as bonding_or_by a screw.
An_excitation_light_passing through_the first dielectric_reflection_film 7_is_absorbed by the laser crystal 4._A_fundamental wave oscillated by the laser crystal_4 is reflected between_the_first dielectric reflection film_7 and the second dielectric_reflection film 8, and a second_harmonic generated_from the_nonlinear optical medium 5 is projected through the output mirror 6.
As_described above, the nonlinear optical medium_5 is a medium_of negative_temperature._In order to_obtain_predetermined stable_second harmonic output, it is necessary to_perform temperature_control of the nonlinear optical medium_5. The nonlinear optical_medium_5 is cooled down by the_Peltier element 14 via the optical_resonator block 11.
The temperature of_the_nonlinear_optical medium 5 is detected_by a thermister 17 installed in_the optical resonator_block 11. Based on the detected temperature_of_the thermister 17, electric current to_the_optical resonator block 11 is controlled,_and_the_temperature of the nonlinear optical_medium 5 is controlled via the_optical resonator block 11.
The output of the laser beam_becomes higher in_recent years, and the laser_light_source_2 comprises now a plurality of semiconductor lasers instead of_a single_semiconductor laser. As_a method in order to bundle the laser beams emitted_from a plurality of semiconductor lasers to_a single luminous flux, such method is adopted that the laser_beams emitted from the semiconductor lasers are received_separately through corresponding optical fibers, and the_optical fibers are bundled_together_to form a single cable. By this_cable,_the_laser_beams are guided_to the condenser_lens 3, and_a single_luminous flux is_projected.
In the_conventional example as_described_above, the nonlinear optical medium 5 is cut out in such manner that the nonlinear crystal axis of_the nonlinear optical medium 5