Support device and stage assembly for a scanned-probe microscope

A support device for a scanned-probe microscope comprises a horizontal base member and a vertical bridge member that are transverse to one another. The horizontal and vertical members are connected at their respective opposite ends by a common chord member extending between the ends. The device preferably includes means for attaching a scanned-probe microscope to a forward surface of the vertical bridge member. The support device preferably further includes one or more bracket members, each attached at one end to the rearward surface of the vertical bridge member and at the opposite end to a rearward surface of the chord member. Each bracket includes a section extending away from the chord member. The horizontal base member and the chord member each has an upper surface substantially coplanar with one another. The substantially coplanar upper surfaces together provide support for a readily separable sample plate. Further in accordance with the invention, a microscope stage assembly comprises the described support device and a readily separable sample plate.

FIELD OF THE INVENTION 
The present invention has to do with microscopy and more particularly, to a 
support device and a stage assembly for a scanned-probe microscope. 
BACKGROUND OF THE INVENTION 
Traditional optical microscopes that use lenses to focus visible light 
radiation are limited by the diffraction of the radiation to resolve 
details no smaller than about 200-250 nanometers. However, atomic scale 
details of samples can be resolved by a class of microscopes generally 
referred to as scanned-probe microscopes. One such type of instrument, a 
scanned tunneling microscope, utilizes an electrical potential across the 
gap between the probe tip and the sample to form a measurable tunneling 
current of tip and sample surface electrons. Another type of microscope, 
known as an atomic force or a scanning force microscope, makes use of 
force arising between probe and sample atoms that causes measurable 
deflection of a cantilever bearing the probe tip. Examples of atomic force 
and scanning probe microscopes are shown in one or more of the following 
U.S. Patents which are incorporated by reference: 5,306,919; 5,260,572; 
5,388,452; 5,483,064, and 5,198,715. 
Regardless of the particular type of microscope employed, examination of 
atomic scale features of a sample requires a highly spatially stable 
environment, free of extraneous uncontrolled movement that could 
unpredictably affect the instrument and/or sample. To prevent such adverse 
conditions, a microscope is typically bolted or otherwise permanently 
attached to a heavy sample plate that may be, for example, a granite 
block. This arrangement can cause substantial difficulties should the need 
arise to move the instrument and attached sample plate. The weight of the 
plate makes its transport unwieldy, in the course of which damage to the 
delicate, relatively light microscope may occur. A convenient means for 
connecting the microscope and sample plate for operation under spatially 
stable conditions that allows the plate to be readily removed without the 
use of tools, thereby facilitating relocation of the apparatus when the 
need arises, would be desirable. The support device and stage assembly of 
the present invention provide this benefit. 
SUMMARY OF THE INVENTION 
A support device for a scanned-probe microscope comprises a horizontal base 
member and a vertical bridge member that are transverse to one another. 
The horizontal and vertical members are connected at their respective 
opposite ends by a common chord member extending between the ends. The 
device preferably includes means for attaching a scanned-probe microscope 
to a forward surface of the vertical bridge member. 
The support device preferably further includes one or more bracket members, 
each attached at one end to the rearward surface of the vertical bridge 
member and at the opposite end to a rearward surface of the chord member. 
Each bracket includes a section extending away from the chord member. 
The horizontal base member and the chord member each has an upper surface 
substantially coplanar with one another. The substantially coplanar upper 
surfaces together provide support for a readily separable sample plate. 
Further in accordance with the invention, a microscope stage assembly 
comprises the described support device and a readily separable sample 
plate.

DETAILED DESCRIPTION OF THE EMBODIMENTS 
Referring to FIGS. 1A, 1B and 1C, microscope stage assembly 100 includes a 
support device 101 having a horizontal base member 102 and a vertical 
bridge member 103 that are transverse to one another and connected at 
their respective opposite ends by a common chord member 104. In the 
embodiment depicted in FIGS. 1A, 1B, and 1C, both horizontal member 102 
and vertical member 103 have arcuate shapes. Horizontal arcuate member 102 
and chord member 104 each has an upper surface, 105 and 106, respectively, 
that are substantially coplanar with one another and together provide 
support for separable sample plate 107. Upper surfaces 105 and 106 are 
optionally provided with sample plate contact points 108. Members 102 and 
104 each have lower surfaces, 109 and 110, respectively, that are 
substantially coplanar with one another. Lower surfaces 109 and 110 are 
optionally provided with base support points 111, which are preferably 
located directly beneath corresponding sample plate contact points 108. 
Forward surface 112 of vertical arcuate member 103 is, in a preferred 
embodiment, provided with means such as mounting plate 113 for attaching a 
microscope M to support device 101. Mounting plate 113 is preferably 
disposed at substantially the midpoint of vertical member 103. 
In a further preferred embodiment of device 101, two bracket members 114 
are each attached to rearward surfaces 115 and 116, respectively, of 
vertical member 103 and chord member 104. Bracket members 114 each 
includes a section 117 that extends away from rearward surface 115 of 
chord member 104 and has an upper surface 118 that is substantially 
coplanar with surfaces 105 and 106 and may optionally include a sample 
plate contact point 108. Sample plate 107, which is readily separable from 
support device 101, rests on sample plate contact points 108. 
FIG. 2 is a perspective view of support device 101 that does not include 
microscope M and sample plate 107. Shown in FIG. 2 is an optional 
rigidizing member 201 connecting horizontal base member 102 and vertical 
bridge member 103, both depicted as having optionally arcuate shapes. The 
horizontal base member 102 may also comprise a solid member as indicated 
by the dash lines 150 as shown in FIG. 2. In that case, the chord member 
104 is integral with the solid base member 150. 
The rigid construction of support device 101 and the weight of sample plate 
107 minimize the interfering effects of mechanical vibrations on the 
generally lower frequency resonances provided by piezoelectric or 
electrostrictive materials used in scanned-probe microscope actuators. 
Support device 101 is preferably constructed of a metal alloy with a low 
coefficient of thermal expansion, and sample plate 107 is preferably a 
granite slab. 
FIG. 3 is a perspective view of a preferred embodiment 301 of the support 
device of the invention. Embodiment 301 differs from embodiment 101 (FIG. 
2) in the broadening of the upper portion of vertical arcuate member 302 
bearing microscope mounting plate 113, the addition of horizontal 
rigidizing member 303 connecting chord member 104 and horizontal arcuate 
member 102 at their respective midpoints, and the inclination of bracket 
members 304 towards one another. This disposition of bracket members 304 
is clearly illustrated in the rearward plan view of device 301 in FIG. 3A. 
Sample plate contact points 305a, 305b, and 305c of device 301, together 
with correspondingly positioned base contact points on the lower surface 
of sample plate 107 (FIGS. 1A-C) provide a kinematic mount that dampens 
the effect of external mechanical vibrations and thereby enhances the 
reliability of sample surface measurements by the piezoelectric or 
electrostrictive actuator of a scanned-probe microscope. In the depicted 
embodiment, contact point 305a is a depression in upper surface 106 of 
chord member 104, preferably a slot at an angle of 45 degrees to the 
length dimension of chord member 104. Contact point 305b is also a 
depression in surface 106, preferably conical in shape. Contact point 305c 
is disposed on the planar upper surface 105 of horizontal arcuate member 
102. This configuration of sample plate contact points 305a-c is more 
clearly illustrated in FIGS. 3B and 3C. 
The aforementioned kinematic mount includes contact points 305a-c together 
with three corresponding base contact points, each preferably a 
hemispherically shaped nub on the lower surface of sample plate 107. 
Alternatively, the kinematic mount may be formed in a reverse 
configuration, with slot- and conical-shaped depressions and a flat point 
on the lower surface of sample plate 107 corresponding to three 
substantially hemispherically shaped sample plate contact points 108, as 
shown in FIGS. 1A-C. 
Thus, the microscope stage assembly of the present invention provides a 
stable environment for accurate and reproducible microscopic observations 
and measurements. At the same time, the easy separability, without the 
need for tools, of the heavy sample plate from the support device and 
attached microscope facilitates relocation of the apparatus as the need 
arises. 
The present invention has been described in detail for the purpose of 
illustration, but it is understood that such detail is solely for that 
purpose, and variations can be made therein by those skilled in the art 
without departing from the spirit and scope of the invention, which is 
defined by the following claims.