Nd:YAG pumped optical parametric oscillator

Because the irradiating laser beam is pulsed, MALDI is optimally combined with a TOP mass analyzer. The unlimited mass range of TOP and its ability to acquire the entire spectrum from a single laser pulse event are other factors in favor of the MALDI/TOF-MS combination. MALDI-TOF has become a well-known acronym for many researchers. Quadrupole, ion trap, and Fourier transform ion cyclotron resonance (FT-ICR) instruments have also been modified to accommodate MALDI. A schematic diagram of MALDI/TOF-MS is presented in Figure 2.10. A variety of laser systems has found applications in MALDI analysis, and the most common ones use LTV lasers such as the N2 laser (337 nm), the frequency-tripled (355 nm) and frequency-quadrupled (266 nm) Nd YAG laser, and the ArF excimer laser (193 nm). IR lasers have also been used to produce the MALDI effect. The transversely excited atmospheric (TEA) CO2 laser (10.6 p,m), the Q-switched Er YAG laser (2.94 (im), and the CriLiSAF or Nd YAG pumped optical parametric oscillator (OPO) laser (3.28 p,m) are the common IR lasers. UV and IR lasers yield similar spectra for proteins, although better resolution has been obtained for some proteins with an IR laser. 

The dissociation laser light between 230 and 305 nm was produced by frequency doubling the output of an optical parametric oscillator (Spectra-Physics MOPO-730) pumped by an injection-seeded Nd YAG... 

The wavelength region below 720 nm cannot be accessed directly by the titanium-sapphire laser but is covered by another laser system, e.g., the optical parametric oscillator (OPO). The OPO system consists of a birefringent crystal, e.g., BBO (BaB204), placed within an optical cavity irradiated by an intense pump beam such as a Nd YAG laser that is operated at its third harmonic (355 nm). Through nonlinear interaction the pump beam is split into an idler beam and a signal beam, which generate a... 

A variety of other pulsed laser light sources have been incorporated into optical emission spectrometer systems. The two most common ones are based on either a pulsed nitrogen laser or a frequency-upconverted pulsed Nd YAG laser as either a single line source (337 nm for the nitrogen laser, 266,355, or 532 nm for the Nd YAG laser) or used as a pump laser for a tunable secondary laser device such as a dye laser or an optical parametric oscillator (OPO). The ultimate wavelength tunabUity in such systems depends on the characteristics of the secondary laser and can be substantial in the case of the OPO, but at a substantial price in both cost and complexity of operation and maintenance. Nonetheless, these sources can have excellent temporal characteristics (sub-nanosecond pulse durations) and high per pulse energies. 

Figure 6 Block diagram of the two-color optical parametric amplifier (OPA) and IR-Raman apparatus. CPA = Chirped pulse amplification system Fs OSC = femtosecond Ti sapphire oscillator Stretch = pulse stretcher Regen = regenerative pulse amplifier SHGYAG = intracavity frequency-doubled Q-switched Nd YAG laser YAG = diode-pumped, single longitudinal mode, Q-switched Nd YAG laser KTA = potassium titanyl arsenate crystals BBO = /J-barium borate crystal PMT = photomultiplier tube HNF = holographic notch filter IF = narrow-band interference filter CCD = charge-coupled device optical array detector. (From Ref. 96.)...

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