CARS 显微光路常用光源激光器分类1 新加坡黄志玮组The output of a femtosecond Ti:sapphire laser wavelengths tunable from 700 to 1000 nm, pulse duration of 120 fs, spectral linewidth full width at half maximum FWHM of 8 nm, repetition rate of 76 MHz, horizontal polarization, Mira 900, Coherent, Inc. pumped byaNd:YVO4 laser 10 W Verdi, Coherent, Inc. is divided into two parts by a beam splitter. One of the beams works as the pump beam, and the other is used to pump an optical parametric oscillator wavelengths tunable from 1100 to 1600 nm, Coherent, Inc. to produce the Stokes beam.探测那聚苯乙烯小球，只需要泵浦光是 24mw，探测光是 0.52mw 就能产生他们开始有的实验用的物镜的数值孔径也就是才 0.95 就行2 （2006）加州大学小组Femtosecond pulses for the pump/ probe and Stokes beams are generated by a home-built Ti:Sapphire oscillator and are amplified by a regenerative amplifier (90 fs, 1 kHz, Spectra Physics, Spitfire) before entering an optical parametric amplifier (OPA) (Light Conversion, TOPAS) that generates the near-infrared idler pulse for the Stokes beam (s). The degenerate pump/probe beam (p/p) is generated by using a small amount (5%) of the s-polarized 800 nm beam from the amplifier, which is picked off by a beam-splitter before entering the OPA. This pulse makes four passes between two gratings (800 nm blaze, 830 grooves/mm, Edmund Industrial Optics), stretching the pulse in time due to the induced linear negative temporal chirp, and resulting in the blue frequencies of the pulse leading the red frequencies in time. The near-infrared (2100 nm) s-polarized idler beam from the OPA is frequency-doubled by a BBO crystal to a p-polarized 1050 nm Stokes beam, and temporally overlapped with the pump/probe beam by using a delay stage. The average powers of the pump/ probe and Stokes beams can be varied from 0.2 to 10 mW and 0.02 to 2 mW, respectively. The Stokes beam is tunable from 800 to 1175 nm, corresponding to Raman shifts from 0 to 4000 cm 1, when employing the appropriate optics for spatially overlapping the pump/probe and Stokes pulses.3 Alison 小组 （2006）Chemically Selective Imaging with Broadband CARS Microscopy利用 10fs 超宽带激光器,然后没有使用啁啾，而是采用在频域上一个 2nm 的小范围引入一个 180 度相位差和不同的偏振太。本文可以实现单光束探测，而且探测的是所有像素的光谱信息。通过光谱信息来合成像，一个图像大概需要 3 分钟。但是有点没有太看的懂4 采用 This has been achieved with high-repetition rate picosecond laser systems that consist of two electronically synchronized mode-locked Ti : sapphire oscillators operat-ing at 80MHz (Spectra-Physics, Tsunami/Lock-to-Clock) or at 76MHz (Coherent,Mira/Synchro-LockAP). The pump and Stokes pulse widths are typically about 5 ps, correspond- ing to a spectral width of 2.9cm1 . The wavelength of each laser beam can be independently tuned, which results in an adjustableRaman shift covering the entire spectrum molecu-lar vibrations from100 to 3400 cm15 In a different approach,Hellerer R67Topical Review et al 93 have demonstrated femtosecond CARS microscopy using both linearly chirped pump and Stokes pulses with the same amount of chirp. This way, the entire bandwidth of both pulses is focused into a narrow spectral region, resulting in a higher spectral resolution (3cm1 ).Chirped pulses are produced by rst generating nearly transform limited 170 fs pulses at 798 nm using a regenera-tively amplied fs laser system with a repetition rate of 250 kHz (Coherent, Mira, RegA9000). From these, 70 fs pulses tunable between 550 and 800 nm are obtained by fre-quency doubling the signal from an optical parametric am-plier (Coherent, OPA9800). The tunable light serves as the pump laser at 683 nm and 5% of the RegA output are di-rectly used as the Stokes laser (Fig. 1). The required chirp is accomplished for both beams independently by means of pulse stretchers consisting of a double-pass grating-lens combination, as commonly used in chirped pulse amplication. Besides ,the chirp parameter should be identical6 最常见的：Recently, Xie and co-workers 95 have implemented high frame rate CARS imaging based on a high repetition rate mode-locked picosecond laser pumped optical parametric oscillator (OPO) system. Since the wavelength-tunable OPO output pulse is deterministically related to the phase of the repetition frequency of the pump laser output pulse, such a laser system provides inherently synchronized pump and Stokes pulses, obviating the need for complex electronic synchronization schemes, and is thus much less vulnerable to external perturbations. 7 基本参数，功率对应着 5-100mw8 采用激光器振荡级和光子晶体光纤，实现高重复频率高调节范围的光源，光子晶体光纤只需要振荡级的数百毫瓦功率就可以了，最终入射到样品之上的功率是 2mw 左右就可以。缺点是飞秒的脉宽还是比较短。本方案还是相当于采用飞秒光源，光纤就好像是 opo，感觉可以为本实验室所用。Fs laser 就是普通振荡级，光子晶体光纤的长度为 4cm，光子晶体光纤入射光强度 25mw 就足够了，采用透镜偶合金光纤内部。本文还是采用的 XYZ 平移台不知道为啥。然后在入射光为 795nm 情况下，光纤产生的最长波长是 643nm，对应着 3000cm-1，可以对 C-H 键探测。对应着不同的入射光波长，光纤会有不同的输出波长，所以就可以是实现调节了。本质还是飞秒光源，没有达到超宽带的效果。作者提出可以采用窄带滤波片加在泵浦光和探测光上，来提高最后图像的分辨率。9 这个是比较真正的超宽带。本文是采用 MIRA 900 作为振荡级，重复频率 76MHZ，波长大概为 795nm，时间大概为150fs，输出的光纤经过 DF 选光，其中选出的窄带作为泵浦光，由于频域变窄，所以时域变宽，成为 1.2ps，剩下的 200mw 呗用来泵浦这个 taper fiber，会产生波长为 400-1000 的超宽带光，由于光线内部产生啁啾，所以脉宽大