microscope thermal lenses and other special LWIR lenses
We develope a 532nm laser microscope based on the microscope thermal lenses and other special LWIR lenses effect induced by a coaxial beam comprised of excitation and probe beams. The scheme allows the measurement of absorption factors down to 1.2 × 10−7 in a 0.35 μm3 volume by use of a heating laser power of 200 mW incident upon the sample. Results prove that a 450 nm axial resolution is possible when a water immersion objective microscope thermal lenses and other special LWIR lenses with a N.A. of 1.2 is used.
Microscope thermal lenses and other special LWIR lenses provides high-sensitivity measurements for thermal and spectroscopic characterization or detection and imaging of low-absorption samples. Microscope thermal lenses and other special LWIR lenses microscopy combines the high sensitivity of photothermal techniques with the lateral and axial resolution of conventional microscopy. The microscope thermal lenses and other special LWIR lenses generated by a heating beam induces a change in divergence and beam-waist position of a probe beam that are detected with the help of an aperture placed in the path of the beam in front of a photodetector.
With this detection method the signal is maximum when the microscope thermal lenses and other special LWIR lenses is located at a distance of one heating beam’s Rayleigh range from the probe beam’s waist; it is null when the microscope thermal lenses and other special LWIR lenses lies in the plane of the probe beam’s waist.