A beam centering method for near-field microscopy based on shear interference
A technology for detecting beams and near-field microscopy, applied in the field of precision engineering, can solve problems such as poor real-time response capability and complex structure, and achieve the effects of low cost, compact and simple structure, high stability and sensitivity
Active Publication Date: 2020-09-25
FUDAN UNIV
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Problems solved by technology
However, the currently commonly used Shack-Hartmann wavefront detector has a complex structure, and needs to collect multiple images, and its real-time response capability is poor.
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Embodiment 1
[0020] Embodiment 1: according to the appended figure 1 As shown, the detection optical path is built on the basis of the atomic force microscope. After the beam is collimated, the helium-neon laser is used to pass through the sample to be measured from the bottom and focus on the tip of the probe through a convex lens. The angle between the incident beam and the plane of the sample stage is 50° . Place the signal detector at a symmetrical position on the lower side, and first perform rough focusing based on the total energy collected in the detector. Then set the shearing interference optical path above the incident light. The angle between the shearing beam and the shearing beam splitter is 60°, and the deflection angle is 20° relative to the incident beam. The amount of deflection is enough to prevent the incident light from directly entering the interference optical path. The test sample was removed, and the Shack-Hartmann wavefront detector was used to detect the diffrac...
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The invention belongs to the precision engineering technology field and especially relates to a near-field microscopic detection light beam centering method based on a shear interference. The method comprises the following steps of in an atomic force microscopic system, making a laser beam be focused on a probe tip from a lower portion of a sample, wherein an included angle between incident beam and the sample is 40 degree to 50 degree; installing a convex lens from an inclined top and changing a scattered divergent light beam into approximately parallel light; then, placing a shear beam splitting plate and forming a shear interference optical path, wherein the included angle between a shear light beam and the beam splitting plate is 60 degree to 70 degree; and placing a detection screen on a reflected light beam, and determining a centering condition of a detection light beam at the probe tip through an interference fringe. The method has advantages that high sensitivity of laser interference is effectively used, and a centering deviation is determined through an overall fringe image of the shear interference; and an interference light beam does not pass through a tested sample, and is not interfered by surface fluctuation of the sample and a material property so that accurate focusing of a detection laser beam can be realized, and the method is important for improving efficiency and precision of near-field microscopic measurement.
Description
technical field [0001] The invention belongs to the technical field of precision engineering, in particular to a method for centering a near-field optical detection beam in an atomic force microscope. Background technique [0002] In modern micro-nano processing and precision measurement, atomic force microscope is a commonly used tool for shape measurement and atomic manipulation. For transparent samples, the transmission near-field optical microscope can excite surface plasmons, break through the diffraction limit, and significantly improve the measurement resolution. Therefore, the two can be combined to irradiate the laser beam directly on the atomic force tip, and use the near-field enhancement effect of the tip to achieve the effect of super-resolution optical measurement. Only when the incident light beam is optimally centered on the probe tip can the light utilization efficiency be the highest, and the outgoing wavefront is close to a spherical wave, with less disto...
Claims
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IPC IPC(8): G01M11/02G01Q60/24
CPCG01M11/02G01Q60/24
Inventor 张祥朝程宇徐敏
Owner FUDAN UNIV