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The principle is that the two laser beams, the incident angle θ (gas, θ ≈ 0; liquid or solid, θ is a small angle) to the sample frequency ν1 and ν2. Typically, ν1 fixed, and change the ν2 scan. When Δν = and ν1-ν2 is equal to the molecular vibration frequency, resonance enhanced to get a frequency ν3 = and ν1 + Δν ν3 = 2ν1-ν2 strong signal. The recorded scattering intensity along with the the Δν changing map, ie coherent anti-Stokes Raman scattering spectroscopy (Δν> 0) or coherent Stowe Alex Raman scattering spectra (Δν <0). Many families want to buy  green laser pointer  for fun.
At present, coherent anti-Stokes spectra of a wider application, this coherent Raman spectroscopy in addition to the same information of the samples with the general Raman spectroscopy, has the following advantages: (1) to strengthen due to resonance, the high conversion efficiency, general 10-5-10-8 for the efficiency of Raman spectroscopy, and coherent anti-Stokes Raman spectrum efficiency is greater than 10-2; ordinary Raman spectrum of the laser light source power of 100 milliwatts to 2 watts, while the Coherent anti-Stokes spectra of the laser power is only 1-2 mW. This effectively prevents the sample heat damage, biochemical analysis of samples. (2) ordinary Raman scattering light distribution in all directions, and coherent anti-Stokes Raman scattering light is a clear beam, spatially separated, and the incident light, so no monochromator, with a simple the Iris Diaphragm interference filter can be. The  led flash light  is a good choice for the gift.
And ν1 of coherent anti-Stokes Raman scattering the frequency ν3 = and ν1 + Δν (Δν> 0), while the fluorescence in the ν is ≤ the range, so effectively inhibit the fluorescence interference to overcome the difficulties in the analysis of colored samples. A very wide range of applications of laser Raman spectroscopy. In the identification of molecules, the molecular structure of the research, the study of surface adsorption, chemical catalysis, phase change of the microscopic process of research, monitoring of environmental pollution, organic chemistry, polymer chemistry, petroleum chemistry, and biochemistry have made good effect. Space high-resolution laser microscopy spectra of the special requirements of science and technology, sample accurate positioning of the micro-area analysis, has been a research topic of general interest. The emergence of the laser, with its high intensity and collimation opens up new ways that the various forms of spatial high-resolution laser spectroscopy. One of the more mature and widely used laser microscopy spectroscopy. The  green laser pointer  can be bought easily.
Laser micro-spectroscopy experimental device consists of four parts laser, micro-optical systems, electronic control system, spectrograph or light meter. Figure (10-14) as shown by the laser (usually Q-switched solid-state lasers) issued by the laser beam is fired at the sample through the microscope objective, the sample evaporation in the region between the auxiliary electrode, the formation contains a certain number of electron, ion vapor cloud. Then, the electricity stored in the auxiliary electrode on the circuit capacitance through L, the R discharge in the vapor cloud, so that the atoms in the vapor cloud, the ion excitation and emission spectra. The use of microscopic optical system, lighting system to illuminate the sample. For opaque specimens, with a reflective optical path to illuminate the sample, the sample reflection illumination beam transflective mirror, steering prism into the eyepiece; adjust the position of the specimen through the eyepiece, and micro-alignment laser to be analyzed beam (ie, a microscope objective lens optical axis direction). Transparent sample, the transmission optical path to illuminate the sample from below. The new design of  green laser pointer has got the approval.
Set up a neodymium glass laser light source, λ = 1.06μm, the effective diameter of 6mm, then α ≈ 2 × 10-4 radians. But, in fact, deviate from the axial oscillation mode, and thus the observed value of α is larger than the calculated value, usually 10-3 radians. This laser beam focal length f microscope objective focused on the sample surface, the spot diameter (see Figure 10-15): At present, the spectral analysis of laser capture microdissection, the design and manufacture of a catadioptric microscope objective. magnification of 40, the focal length of about 6 mm (16 mm working distance), the use of this type of microscope objectives, spot diameter of about 10 microns. The quality assurance of  green laser pointer  has achieved a good result.