Scanning probe microscope

1. A scanning probe microscope to measure a sample set on a sample mount in a liquid, the microscope comprising:

a scanning mechanism to scan a cantilever provided with a probe at a free end along an X-axis, a Y-axis, and a Z-axis perpendicular to each other; and

a liquid contact member which includes an optical transmission portion to transmit detection light for detecting a displacement of the cantilever, and which is arranged at least partially in contact with the liquid,

wherein the liquid contact member includes a cell forming portion which forms, in cooperation with the sample mount, a liquid cell having an interface between the liquid and air,

wherein the scanning mechanism includes a holder to hold a cantilever chip including the cantilever, wherein the liquid contact member has a through hole, and wherein the cantilever chip and at least a part of the holder project into the liquid through the through hole,

wherein a gap between the through hole and the holder is sealed in watertight by an elastic member, and

wherein the elastic member is placed between the through hole and the holder so that a motion of the holder caused by the scanning mechanism is substantially absorbed by the elastic member.

2. The scanning probe microscope according to claim 1 , further comprising a support member to support the scanning mechanism and the liquid contact member.

3. The scanning probe microscope according to claim 1 , wherein the liquid cell has an interface between the liquid and the liquid contact member, an interface between the liquid and the sample mount, and the interface between the liquid and air.

4. The scanning probe microscope according to claim 1 , wherein the optical transmission portion is constituted by a second through hole formed in the liquid contact member, and an optical transmission plate to close the second through hole.

5. The scanning probe microscope according to claim 1 , further comprising a displacement sensor to detect a displacement of the cantilever, wherein the displacement sensor includes a light converging element to be scanned by the scanning mechanism together with the cantilever.

6. The scanning probe microscope according to claim 1 , wherein the scanning mechanism includes an X-Y scanner to raster-scan the cantilever along the X-axis and the Y-axis, and

wherein when the X-axis is set as a high-speed axis of the raster scanning and the Y-axis is set as a low-speed axis of the raster scanning, the cantilever is arranged so that a longitudinal direction thereof is along the Y-axis.

7. The scanning probe microscope according to claim 1 , wherein the cell forming portion is arranged at a position opposite from the sample mount across the sample, so as to cooperate with the sample mount to sandwich the liquid, thereby forming the liquid cell.

8. The scanning probe microscope according to claim 1 , wherein the optical transmission portion comprises at least a part of the cell forming portion.

9. The scanning probe microscope according to claim 1 , wherein the scanning mechanism scans the cantilever with a part of the liquid being in contact with air.

10. A method of measuring a sample set on a sample mount in a liquid, the method comprising:

arranging a cantilever provided with a probe at a free end in the liquid;

arranging a liquid contact member including an optical transmission portion immovably, with at least a part of the liquid contact member being in contact with the liquid, so as to form a liquid cell having an interface between the liquid and air;

scanning the cantilever in the liquid cell; and

optically detecting movement of the cantilever during the scanning through the optical transmission portion,

wherein the liquid contact member has a through hole, and

wherein the cantilever is arranged in the liquid by:

holding a cantilever chip including the cantilever with a holder,

holding the holder through the through hole,

projecting the cantilever chip and at least a part of the holder into the liquid, and

watertightly sealing a gap between the through hole and the holder by an elastic member, wherein the elastic member is placed between the through hole and the holder so that a motion of the holder caused by scanning the cantilever in the liquid cell is substantially absorbed by the elastic member.