Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Reexamination Certificate
1999-11-05
2001-09-25
Le, Que T. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
C250S307000
Reexamination Certificate
active
06294774
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a scanning probe microscope, such as an atomic force microscope or a friction force microscope.
2. Description of the Related Art
In an atomic force microscope, a force exerted between a cantilever and a sample induces a mechanical displacement of the cantilever. Generally, the displacement is measured with an optical lever. In this scheme, a focused laser beam is made to hit the back surface of the cantilever. The reflected light is detected by a photodiode that is segmented into four parts, for example. Thus, the displacement of the cantilever is measured.
When no force is exerted between the cantilever and the sample, it is important that the laser light reflected off the cantilever impinge on the proper position of the light-sensitive surface of the photodiode, i.e., its center. An adjustment for this is made by a human operator who adjusts the position of the photodiode while directly viewing the light-sensitive surface of the photodiode such that the laser light hits the center of the surface.
However, the photodiode is small and so it is very difficult to adjust the position in such a way that the laser light hits the center of the surface.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a scanning probe microscope that facilitates adjusting the position on the photodiode hit by light.
The above-described object is achieved in accordance with the teachings of the present invention by a scanning probe microscope in which light emitted from a light source is directed to a cantilever and light reflected off the cantilever is detected with an optical detector to measure the displacement of the cantilever. This scanning probe microscope comprises: information-finding means for finding information about the position on the light-sensitive portion of the optical detector hit by the light, based on the output from the light-sensitive portion; storage means for storing graphical information about the light-sensitive portion; and control means for displaying a picture of the light-sensitive portion, based on the graphical information stored in the storage means and for displaying a marker indicating the position on the light-sensitive portion hit by the light, based on output from said information-finding means, in such a way that the marker is superimposed on the picture of the light-sensitive portion.
Other objects and features of the invention will appear in the course of the description thereof, which follows.
REFERENCES:
patent: 5359417 (1994-10-01), Muller et al.
patent: 5481908 (1996-01-01), Gamble
Ito Takashi
Nakamoto Keiichi
Jeol Ltd.
Le Que T.
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
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