| 摘要 |
PROBLEM TO BE SOLVED: To improve the detection sensitivity of the displacement of a cantilever. SOLUTION: A light beam OB1 from a light source 1 is appropriately focused at the side of a sample 5 from the reverse side (a surface that is opposite to a sample surface side) of a cantilever 2. Namely, the beam is underfocused on the reverse side. Then, the image of a just focus image P' (the real image of the light source) is formed at the symmetrical position of a just focus image P (the imaginary image of the light source) at a light detection side (light source side) in reference to the reverse side. Then, a reflection light beam from the reverse side enters the light reception surface of a photo detector 4 according to an optical diagram as shown by RB1, so that the spot diameter of a reflection light beam on the light reflection surface becomes S1, which is extremely smaller than a conventional case where the image is just focused on the reverse side, thus improving the detection sensitivity of the displacement of the cantilever 2 due to the photo detector 4.
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