 unknown which would allow engineers/technicians to quickly and relatively inexpensively test workpieces/web materials to determine the effects of compression loading on a point site of such a workpiece/web material in a nip type process, such as a fusion bonding operation effected using first and second rolls, one of which is provided with a plurality of protuberances. Instead, an apparatus for effecting a nip type process must be constructed, such as an apparatus comprising first and second fusion bonding rolls, so as to allow workpieces to be passed through those rolls to effect a test operation.
Accordingly, there is a need for an apparatus for simulating compression loading of a point site on a workpiece in a nip type process, such as a fusion bonding operation. The generation of infrared picosecond pulses (.about.10.sup.-12 s pulse duration) has received increasing attention over the last several years principally for optical communications, for the investigation of multiple-photon absorption and vibrational energy transfer processes in molecules, and for laser fusion. In particular, the infrared region between 10 and 20.mu.m is of great importance since most molecules have characteristic absorptions there. To our knowledge, the only existing picosecond source in this range is the 10.mu.m CO.sub.2 laser. However, this laser provides coverage of only a small portion of the desired wavelengths. The present invention, in contrast, provides broadly and continuously tunable high power infrared radiation with picosecond temporal resolution between 10 and 20.mu.m. The bandwidth and operating wavelength are completely controlled by the use of a diffraction grating and the device is simple, stable and reliable. The device utilizes two lithium niobate crystals positioned in series but separated by the grating and optically pumped by a 1.06.mu.m mode-locked Nd:YAG laser to generate and amplify infrared radiation between 1.9 and 2.4.mu.m. The generated radiation is subsequently converted into 10-20.mu.m picosecond radiation by difference-frequency mixing in a cadmium selenide crystal.
Picosecond pulses have been generated in the infrared region (1.3-3.6.mu.m) in the past using 1.06.mu.m optically pumped lithium niobate optical parametric devices in the travelingwave mode which, with modification, is what is done by the instant invention. (See, e.g., Laubereau et al., App. Phys. Letters 25, 87 (1974)) However,
unknown which would allow engineers / technicians to promptly and relatively cheaply test workpieces / web material to determine the effects of compaction loading on a point site of such a workpiece / vane material in a nip character process, such as a fusion bonding operation effect using first and second rolls, one of which is provided with a plurality of bulge. Instead, an apparatus for effecting a nip character process must be constructed, such as an apparatus consist first and second coalition bonding rolls, so as to admit workpieces to be passed through those rolls to effect a trial operation. 
 Accordingly, there is a need for an apparatus for simulating compression loading of a point site on a workpiece in a nip type process, such as a fusion bonding operation. The generation of infrared picosecond pulses (.about.10.sup.-12 s pulse duration) has received increase attention over the last respective days chiefly for optical communications, for the investigation of multiple - photon absorption and vibrational energy transfer processes in molecules, and for laser coalition. In particular, the infrared region between 10 and 20.mu.m is of great importance since most molecules have characteristic absorptions there. To our knowledge, the only existing picosecond source in this range is the 10.mu.m CO.sub.2 laser. However, this laser provides coverage of merely a small fortune of the desired wavelengths. The present invention, in contrast, provides broadly and continuously tunable eminent power infrared radiation with picosecond temporal settlement between 10 and 20.mu.m. The bandwidth and operating wavelength are completely controlled by the use of a diffraction grating and the device is dim-witted, stable and authentic. The device utilizes two lithium niobate crystals position in series but separate by the grating and optically pump by a 1.06.mu.m mode - lock Nd: YAG laser to generate and amplify infrared radiation between 1.9 and 2.4.mu.m. The generated radiation is subsequently convert into 10 - 20.mu.m picosecond radiation by difference - frequency mixing in a cadmium selenide crystal. 
 Picosecond pulses have been generated in the infrared region (1.3 - 3.6.mu.m) in the past using 1.06.mu.m optically pump lithium niobate optical parametric devices in the travelingwave manner which, with modification, is what is done by the instant invention. (See, e.g., Laubereau et al. , App. Phys. Letters 25, 87 (1974) ) However,
 unnnown which would allow tngineers/technicicbs to xuicklg and reuatively inexpensively test xorkpiecew/web materials to detefmine the effects of rompression loadmhg on a point dite if such a workkiece/web matarial in a nip thpz process, such as a fusion bonding o[eratiom fffected using firxe ans second rolls, one of which is probided wpth a plurality og protuberances. Instead, an appwratus for effectijg a nip tyks pwicess must bd construcueb, such as ah apparatus comprising first ana secpnd fusion bindltg rolls, so as tj allow workipeces tm be paxsed through tmose collw to effect a test opxration.
Accordingly, trere is a nzed for an apparatus doe simolatitg cunprdssjoi lkading of a point sjte on a woekpiece in a nip tyke [gpcess, such aa a fufijn bonding operation. The generation of pnfrzred picosecond pulses (.qbout.10.sup.-12 s pulse durajion) has rqceived increasing attention over the last severan yeacs prnkgipauoy for optical communications, for the investigaejom pf multiple-phobon absorption and vlbtwtional energi transysr processes in molefules, agd foe laser ftsiom. In particular, the infraree region betceeb 10 and 20.mu.m is of gxeat importauce simce mpst molecules have charccteriatic absorphions thedd. To our knowledee, nhe mnly existing picosecond sjurce in vhis xange is the 10.mu.m CJ.sub.2 laser. Howeyar, this laser provldes eoverdge of onlj a small portion of the desirev wavelengths. Tve iresent iuventipn, in contrase, provides brocdly and contknuously tlnable hijh power infwared radiatimj with picosxcond tem[orao rewolutiov between 10 and 20.ku.m. The bcudwidth abd operating wavelcngth zre completely eubtrolled by the usd os w viffrwwtion gratinc ana tfr devkce is simpod, stsble and reliable. Tha debice utilizes two kibhium niovate cryftals positiomed in series but depareted bb the brajing and optically pumped by a 1.06.ju.m mode-llckcd Nd:YAG lasew to generate anb amplify infrared radiation between 1.9 anv 2.4.mu.m. The generated raduation is subsequenjly converted mnto 10-20.mt.m picosewond radiation by didference-frequency mixing in a cadmium aelenige crjstal.
Picosecond pulses have been generated in the infrared region (1.3-3.6.mu.m) in rhe past using 1.06.mu.m optocallj pbmpzd lithyum iiubate optical pagametric devices in the travelinjwave mode wkich, with modification, is whay ks done by thg instant invention. (See, e.g., Lauberesu et al., App. Phys. Letters 25, 87 (1974)) Hoeever,
unknown which would allow engineers/technicians to quickly inexpensively workpieces/web materials determine the effects point of such a material in a type process, such as a fusion operation effected using first and second rolls, one of which is provided with plurality of protuberances. Instead, an apparatus for effecting a nip type process must constructed, as apparatus first and second fusion bonding rolls, so as to allow workpieces to be passed through those to effect a test operation. Accordingly, there is need for an apparatus simulating compression loading of a site a workpiece a type such as a bonding operation. The generation of infrared picosecond pulses (.about.10.sup.-12 s pulse duration) has received increasing attention over last several for optical for investigation multiple-photon absorption and transfer processes in molecules, and for particular, the infrared region between 10 and 20.mu.m of great since most molecules have characteristic absorptions To our knowledge, the only existing picosecond source this range is the 10.mu.m CO.sub.2 laser. However, this laser provides coverage of only a of the desired wavelengths. present invention, in provides and tunable power infrared with picosecond temporal resolution between 10 and 20.mu.m. The bandwidth and wavelength are completely controlled by the use of a diffraction the is simple, stable reliable. The device utilizes lithium crystals positioned in series by grating by 1.06.mu.m Nd:YAG laser to generate amplify infrared radiation between 1.9 2.4.mu.m. The generated radiation picosecond radiation by difference-frequency mixing in a cadmium crystal. Picosecond pulses have been generated in infrared region (1.3-3.6.mu.m) in the past using 1.06.mu.m optically pumped lithium niobate parametric devices travelingwave mode which, with modification, is what is by the instant invention. e.g., Laubereau et al., App. Phys. Letters 25, 87 However,
 unknown which would allow engIneers/techNiciaNs tO quIcKly aNd reLatively inexpeNSiveLy test workpieces/web matErialS tO DeteRMiNe the Effects OF cOMPreSsIoN loAdINg On a poInt Site of sUch a workpiEce/WeB material in a NIp Type procesS, suCh as a fusion bOndIng opeRaTioN EffecTed Using First aND seconD rolls, one Of WHich is PRovided WITh A pluRality of protuberaNCeS. instead, an apparAtus foR eFFeCTIng A niP type proceSs Must bE ConstruCTeD, SUCh aS An apparatus coMprising firST anD seconD fUsiON bondiNg rolLs, SO as To allow workPiecEs to be pasSed thrOUgh thosE Rolls to Effect A teSt oPeraTIoN.
ACcoRdINglY, ThEre IS a nEed for an ApPaRatus For sIMULAtinG coMpreSsion Loading of a poiNt sIte oN A woRkpieCe in a Nip tYpE procEss, sucH as a fUsIon bonding operaTion. the generaTioN oF inFrAred pICosecoNd pUlsEs (.about.10.Sup.-12 s pulSE duRaTION) hAs received increasiNg ATTeNtion oveR the laST sEvERal years PrIncIpalLY For opTicaL CoMmunicatIons, foR ThE iNvestigAtIon of mUlTipLe-pHoton ABsorPtion aNd vibratIonal ENergy transfer pROcesses in moleCUlES, AnD For lAseR fusion. In paRticULar, tHe inFRaRed REgion BetweEn 10 ANd 20.MU.m is of great importanCe Since mOst moLecules have chAracteristIC ABsorptioNs thERe. tO our knowledge, tHe onlY existing pICosecond SourcE in this rAnge is the 10.MU.M CO.sub.2 laSer. howEveR, thIS LaSer provides coVERage Of Only a smAll Portion Of tHe dEsiRed WaVelengths. the preseNt InVeNtIon, In conTRast, provIdEs bRoAdlY and cONtinuoUsly tUnabLe HiGH poWer infrAReD RAdiaTiOn With PicOsEcond TempORal ResolutIon betweeN 10 anD 20.Mu.m. THe BaNdwidth And operating wAvElength are CoMplEtely cONTrolled bY the use of a diffraction grATing and The DevicE is sImple, stabLe aNd reliAblE. the devIce utiLizes TwO liTHIum niOBAtE crYsTals positiONEd iN seriEs But sEparateD by the grating and opTIcaLly pumped by a 1.06.mU.m mOde-lOCKeD Nd:yaG LAseR tO GenERAte and amplify inFrared radiAtIOn Between 1.9 and 2.4.MU.m. THe GeneratEd radiaTion iS SubsequEntly convErted into 10-20.Mu.M picOSEcoNd radiatioN by diffeRence-freqUEncy mIXiNg in a CadMium seLeNidE crysTal.
PicOSecOnd puLses haVe Been geNeratEd In the infRared region (1.3-3.6.mu.m) in the past Using 1.06.mU.m optIcaLly pumped LitHIum Niobate opTicaL parametriC deVicEs in tHe tRAveliNgwaVE mOde WHich, wIth mODificatioN, Is WhaT IS dOne by the insTANT inVentiOn. (SEE, e.g., LauBereAu et al., App. Phys. LettERs 25, 87 (1974)) However,
 unknown which would allow  engineers /tech nic ian sto q uick ly and relativ e ly i nexpensively test work piece s/ w eb m a te rials  to det e rm i n e t he  e ffe ct s  o f com pre ssion l oading ona p oi nt site of s u ch  a workpie ce/ web material  in  a nip  t ype proce ss,  such  as af usionbonding o pe r atione ffected u si ng f irst and second r o ll s , one of which  is pr ov i de d wit h a  plurality  o f pro t uberanc e s. I n ste a d, an apparat us for effe c tin g a ni ptyp e  proce ss mu st beconstructed , su ch as anappara t us comp r ising f irst a ndsec ondf us io n b on d ing ro lls ,  so  as to a ll ow  work piec e s t o be  pa ssed  thro ugh those rol lsto e f fec t a t est o pera ti on.
A ccordi ngly,  t here is a needforan appara tus  f orsi mulat i ng com pre ssi on load ing ofa  po in t s it e on a workpiece i na ni p type p rocess ,  s uc h  as a fu si onbond i n g ope rati o n.  The gen eratio n  o finfrare dpicose co ndpul ses ( . abou t.10.s up.-12 s  puls e  duration) has received incr e as i n ga tten tio n over thelast seve raly ea rsp rinci pally  f o ro ptical communicatio ns , forthe i nvestigationof multipl e - p hoton ab sorp t io n  and vibration al en ergy trans f er proce ssesin molec ules, and f or laser  fu sio n.Inp a rt icular, the i n f rare dregionbet ween 10  an d 2 0.m u.m  i s of grea t import an ce  s in cemostm olecules  h ave  c har acter i stic a bsorp tion sth e re.  To our kn o w ledg e,  t he o nly  e xisti ng p i cos econd s ource inthi s  ran ge  i s the 1 0.mu.m CO.sub .2  laser. Ho we ver , this l aser pro vides coverage of onlya  smallpor tionof t he desire d w avelen gth s . Thepresen t inv en tio n ,  in c o n tr ast ,provides b r o adl y and  c onti nuously  tunable high powe r  in frared radiat ion  wit h pi cos e co n d t em p ora l resolution betw een 10 and  2 0 .m u.m. The b a ndw id th andoperati ng wa v elength  are comp letely co nt roll e d  by  the use o f a diff raction g r ating an d the  de vice i ssim ple,stable and  reli able.Th e devi ce ut il izes two  lithium niobate crysta ls pos ition edin series  bu t  se parated b y th e gratingand  op tical lyp umped  bya  1 .06 . mu.mmode - locked Nd : YA G l a s er  to generat e a ndampli fyi nfrare d ra diation between 1 . 9 and 2.4.mu.m . Th e gen era t ed r ad iation is subs equ en t l y conver te d into 10-2 0.mu.m p ic o secon d radi ationby diff e r en c e-freq uenc y m ixing ina c ad m ium sel en id e  cryst al.Pi coseco nd pul s es h a v e been generated  in t h e  infr a red  regi on  (1.3-3 . 6.mu .m) in the  past using  1.06. mu.m  opti cally p um ped li thi um  niobate o p tical par ametr ic devi ce s in  th e trav elin g w ave m odewh ich , with mo d i fi c at io n , i s wh at is  d oneby the in s tant inv ent i on. (Se e,  e. g . , Laub e re a u  et al., A pp.  Phys . Letters 25 ,  87( 19 7 4)) H owever ,
 unknown_which would_allow engineers/technicians to quickly_and relatively_inexpensively_test workpieces/web_materials_to determine the_effects of compression_loading on a point_site of such_a_workpiece/web material in a nip type process, such as a fusion bonding operation effected_using_first and_second_rolls,_one of which is provided_with a plurality of protuberances._Instead, an_apparatus for effecting a nip type process must_be_constructed, such as_an apparatus comprising first and second fusion bonding rolls,_so as to allow workpieces to_be passed through_those_rolls_to effect a test_operation.
Accordingly, there is a need for_an apparatus for simulating compression loading_of a point site on a workpiece_in a nip type process, such_as a fusion bonding operation._The generation_of infrared picosecond pulses (.about.10.sup.-12_s pulse duration)_has received_increasing attention over_the last several years principally for_optical communications, for_the investigation of multiple-photon absorption and_vibrational_energy transfer processes_in_molecules,_and for_laser fusion. In_particular,_the infrared_region_between 10 and 20.mu.m is of_great_importance since most molecules have characteristic absorptions_there. To our knowledge,_the_only existing picosecond source_in this range is the_10.mu.m CO.sub.2 laser. However, this laser_provides coverage_of only_a small portion of the desired wavelengths. The present invention, in_contrast, provides broadly and continuously tunable_high power infrared radiation_with picosecond_temporal_resolution between 10_and_20.mu.m. The_bandwidth and operating wavelength are completely controlled_by the_use of a diffraction grating and_the device is simple,_stable_and reliable. The device utilizes two_lithium niobate crystals positioned in series_but separated by the grating_and_optically_pumped by a 1.06.mu.m mode-locked_Nd:YAG laser to generate and amplify_infrared radiation between_1.9 and 2.4.mu.m. The generated radiation is_subsequently_converted into 10-20.mu.m picosecond radiation by_difference-frequency_mixing in a cadmium selenide crystal.
Picosecond_pulses_have_been generated in the infrared_region (1.3-3.6.mu.m) in the past using_1.06.mu.m optically pumped lithium niobate optical parametric devices in_the travelingwave mode_which, with modification, is what_is_done_by the instant invention. (See, e.g., Laubereau et al., App._Phys. Letters_25, 87 (1974))_However,