JPH07113589B2 - Optical micro load displacement measuring device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical micro load displacement measuring device for optically measuring a micro load displacement.

[0002]

2. Description of the Related Art Generally, as a method for measuring mechanical deformation or displacement of a member due to load, deformation of the member, such as a strain gauge, is recognized as a change in electric resistance of the strain gauge and converted into an electric signal. Or a method of mounting a piezoelectric element on a member and detecting the capacitance change due to the deformation of the piezoelectric element due to the deformation of the member as an electric signal to grasp the deformation amount.

[0003]

By the way, although the technique for converting mechanical deformation or displacement amount used in various industries into an electric signal is remarkably improved, extremely fine load-displacement measurement is performed. In this case, there is a problem that the method using the strain gauge or the piezoelectric element as described above is difficult to deal with in terms of technical and cost.

An object of the present invention is to provide an optical micro load displacement measuring device capable of accurately measuring a very small load displacement with a simple structure.

[0005]

According to the present invention, a transparent cantilever having a supporting portion at one end and a load point at the other end, and a reference member fixedly supported in close contact with the cantilever. And the cantilever and the reference member respectively have a first optical plane and a second optical plane on the side of the contact surface, and the first optical plane and the second optical plane are provided on the side of the contact surface, and the first optical plane and the second optical plane are displaced by the displacement of the load point. An optical micro-load displacement measuring device characterized by measuring a displacement amount and a load amount at the load point based on a generation position of an interference fringe generated between an optical plane and the second optical plane. can get.

[0006]

The above-mentioned cantilever has a simple shape by highly accurate processing. The generation position and state of the interference fringes generated on the cantilever and the first and second optical planes provided on the reference member change according to the displacement amount at the load point of the cantilever. Therefore, the deformation state at the load point can be grasped by measuring the generation position and state of the interference fringes. Then, for example, the displacement due to the minute load can be accurately known by analytically obtaining the displacement and the load amount at the load point when this deformed state occurs due to the deformation mechanics of the beam.

[0007]

Embodiments of the present invention will be described below. Figure 1
(a) and (b) show an optical micro-load displacement measuring device according to the present invention. In these figures, 1 has a first optical plane 11, and a support 12 at its left end is fixed. The cantilever is fixed to the member 3. This beam 1 is made of a transparent member which has flexibility to be deformed when a load is applied. Reference numeral 2 is a reference member that includes a second optical plane 21 that faces the optical plane 11 and that is wholly fixedly supported by the fixing member 3 or the like.

In the unloaded state, the cantilever 1 and the reference member 2 have their first and second optical planes 11 and 21 in close contact with each other as shown in FIG. The planes 11 and 21 are held in parallel. In the figure, the right end of the cantilever 1 projects to the right from the reference member 2,
A load point A is provided on the reference member 2 side of the right end portion.

A procedure for measuring the load-deformation characteristics of the microsphere by the measuring instrument of this embodiment will be described. Figure 1 (a)
In the figure, a state is shown in which the DUT 4 made of microspheres placed on the support member 5 is in contact with the tip of the load point A of the cantilever 1. The DUT 4 is in contact with the right end portion of the cantilever 1 at the load point A with no load (load W = 0).

From this state, the state where the support member 5 is moved upward by h, that is, the displacement h is given to the object to be measured 4 with respect to the cantilever 1 and the reference member 2, is shown in FIG. 1 (b). Is.
In this case, the DUT 4 is displaced by the deformation amount d with the displacement h, and the displacement amount δA at the load point A of the cantilever 1 becomes a value smaller than this displacement h. Therefore, the displacement amount d of the DUT 4
Is d = h-δA. Incidentally, h can be grasped as the feed amount of the mechanical system, and δA can be obtained as follows.

Next, the displacement δ is calculated by using the beam theory of material mechanics.
The procedure for obtaining A is explained. Load point A as shown in Fig. 2 (a)
When the light R having a single wavelength λ is emitted from the light source provided above the cantilever 1 in a state in which the cantilever 1 is displaced upward, the cantilever 1 as shown in FIG. Such interference fringes 6 occur.

Then, as shown in FIG. 3, for example, the cantilever 1
To the point P at a distance a from the support portion 12 of the right side to the support portion 1
It is assumed that the m-th stripe 6 counted from the 2 side is observed. Regarding the distance between the optical planes 11 and 21 between the cantilever 1 and the reference member 2 at the point P, that is, the displacement amount δP of the cantilever 1 at the point P, the following equation is established.

[0013]

[Equation 1]

On the other hand, according to the material mechanics, the displacement amount δP at the point P when the load W acts on the load point A of the cantilever 1 having the length L is given by the following equation.

[0015]

[Equation 2]

Further, the displacement amount δA of the load point A due to the load W
Is given by the following equation.

[0017]

[Equation 3]

From these equations, the displacement amount ΔA can be obtained by the following equation.

[Equation 4]

Further, by substituting .delta.A into the above equation, the load W at the load point can be obtained by the following equation.

[0020]

[Equation 5]

Then, by measuring the situation such as the interval and width of generation of the interference fringes 6 from above the cantilever 1 by an optical measuring system using, for example, a CCD or the like, the displacement at the load point A by the above procedure. The quantity δA and the load W can be determined. Further, the displacement amount d of the DUT 4 can be calculated from the displacement amount δA and the load W by the above equation d = h-δA.

[0022]

As described above, the optical minute load displacement measuring device according to the present invention has an effect that it is possible to accurately measure an extremely minute load displacement with a simple structure.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of an optical micro load measuring device according to the present invention.

FIG. 2 is an explanatory diagram of interference fringes generated when light having a wavelength λ is emitted in a state where the load point of the cantilever is displaced upward in the load measuring device shown in FIG.

FIG. 3 is a displacement amount d of an object to be measured using the beam theory of material mechanics.
It is explanatory drawing used in order to analytically obtain | require.

[Explanation of symbols]

 1 cantilever 2 reference member 3 fixed member 4 object to be measured 5 support member 6 interference fringe 11 first optical plane 12 support section 21 second optical plane A load point W load δA displacement amount δP displacement amount

Claims (1)

[Claims] 1. A transparent flexible cantilever having one end supported and having a load point at the other end and having a first optical plane extending in a predetermined direction and parallel to the predetermined direction, and the cantilever. A second optical plane is provided on one side of the beam, and the second optical plane is placed in a state in which the second optical plane is in close contact with the first optical plane and supports the cantilever beam without load. A reference member provided, the length from the one end of the cantilever and the load point is longer than the length of the reference member in the predetermined direction, the predetermined wavelength from the cantilever side. Measuring the displacement amount and the load amount at the load point based on the generation interval and the width of the interference fringes generated between the first and second optical planes when the load point is displaced by irradiating An optical micro load displacement measuring device characterized by: