JPH05346301A - Interference-measuring type measuring tape - Google Patents

Abstract

PURPOSE:To make it possible to improve measuring accuracy by measuring a length with an interferometer using the interference of laser light. CONSTITUTION:A base material 4 is pulled out of a containing part 1. A material to be measured 8 is linearly held with a reference stopper 5 and a stopper 7. The distance between the stopper 5 and a reflecting means 15 is measured with an interferometer comprising a head part 3 of the interferometer and a corner cube (reflecting means) 15. In the measurement, at first, the laser light is emitted from the semiconductor laser in the head part 3. The laser light is split into two parts with a splitting part. One laser light is emitted to the means 15 through a rod lens as the measuring light. The light is reflected and returned to the rod lens. The other laser light is reflected from a reference reflecting mirror as the reference light. Two reflected lights, i.e. the measuring light and the reference light, are synthesized in the splitting part. The lights are made to interfere to each other. The interference fringes of the interference lights are measured with a photodetector means. A signal processing means obtains the distance between the stopper 5 and the reflecting means 15 based on the measured information and displays the distance on a display part 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tape measure for measuring a length by using an interferometer.

[0002]

2. Description of the Related Art In a conventional tape measure, a scale (a length measurement) is carried out by engraving a scale on a rollable substrate made of strip-shaped paper, cloth, steel or the like and visually observing the scale.

[0003]

In the conventional tape measure as described above, since the scale is scribed on the band-shaped paper, cloth, steel, etc., this base material expands and contracts under the influence of the use environment. However, this expansion and contraction caused an error in the measurement result. In addition, there was a reading error when visually observing the scale.
Therefore, it was difficult to improve the measurement accuracy, and it was a practical limit to engrave a scale of about 0.5 mm. The present invention is
The present invention has been made in view of such a problem, and an object thereof is to improve the measurement accuracy of a tape measure as compared with the conventional case.

[0004]

For the above purpose, in the present invention, an interferometer is used to measure the length. Then, a strip-shaped base material that can be wound, a reflection means provided at one end of the base material, a storage means for winding and storing the base material from the other end, and a distance between the storage means and the reflection means. A tape measure is constituted by an interferometer head portion for measuring the length (Claim 1).

Also, a strip-shaped base material that can be wound, a storage means for winding and storing the base material from one end, a reflection means provided in the storage means, and the reflection means provided at the other end of the base material. A tape measure was constructed with an interferometer head section for measuring the distance between the tape and the tape (claim 2).

[0006]

In the present invention, the length of the object to be measured is measured by the interferometer. That is, since the moving surface (or the reference surface) is installed at the tip of the base material and the reference surface (or the moving surface) is installed at the storage means side, the base material is moved from the moving surface according to the amount of the base material pulled out from the storage means. The optical path difference between the reflected light and the reflected light from the reference surface changes. Therefore, the length of the object to be measured can be measured by a known method based on this optical path difference, and the length can be measured with high accuracy.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic block diagram showing an embodiment of the present invention. The base material 4 formed in a strip shape is stored in the storage unit 1 in a state in which it can be wound and pulled out. Base material 4
It is desirable to use a highly rigid material.
At one end of the base material 4, a corner cube 15 and a stopper 7 that hooks on the end surface of the DUT 8 and prevents the base material 4 from being rewound are installed. An interferometer head unit 3 is installed in the storage unit 1, and the head unit 3 and the corner cube 15 constitute an interferometer. Further, a reference stopper 5 for giving an origin (reference point) at the time of measurement and a display unit 2 for displaying the measurement result are provided.

FIG. 2 is a schematic diagram showing the structure of the head section 3 of the interferometer. The head unit 3 splits the semiconductor laser 21 which is a laser light source, the optical waveguide 22 through which the laser light 6 emitted from the semiconductor laser 21 propagates, and the laser light 6 from the semiconductor laser 21 into measurement light and reference light. Dividing part 2
3 and a grating mirror 24 that reflects the reference light
It has and. Furthermore, a rod lens (an inhomogeneous lens: for example, a “SELFOC lens” made by Nippon Sheet Glass) 25 for emitting the measurement light to the outside of the optical waveguide 22 or introducing it into the optical waveguide, and a reflection means outside the optical waveguide 22. After being reflected by the (corner cube 15), it is introduced into the optical waveguide 22 again and interferes with the reference light reflected by the grating mirror 24, thereby measuring the interference light. And 26 are provided. And each of these constituent requirements is, for example, GaAs.
It is integrated on a substrate 27 made of.

When the object 8 to be measured is measured, the substrate 4 is pulled out from the housing 1 and the object 8 is sandwiched between the reference stopper 5 and the stopper 7. At that time, the base material 4 is linearly stretched. Then, in this state, the distance between the reference stopper 5 and the corner cube 15 is measured by the interferometer. In the measurement, first, the semiconductor laser 21
The laser light 6 is emitted from. At that time, a switch or the like is provided so that the laser beam 6 is emitted when necessary.

Laser light 6 emitted from the semiconductor laser 21
Propagates through the optical waveguide 22 and is split into two by a splitting unit (for example, a Y-shaped branch) 23. One of the split laser beams propagates through the optical waveguide 22a as measurement light, is emitted from the optical waveguide by the rod lens 25, enters the corner cube 15, and is reflected here. The reflected light from the corner cube 15 enters the rod lens 25 and is introduced into the optical waveguide 22. The other laser light propagates through the optical waveguide 22b as reference light and propagates to the grating mirror 2
It is reflected at 4. And the reference light reflected here is
The measuring light reflected by the corner cube 15 and the dividing section 2
They combine at 3 and interfere with each other in the optical waveguide. The interference light generated by this interference is detected by the light detection means 26. The light detecting means 26 measures the interference fringes of the interference light and sends the information to the signal processing means 28. Signal processing means 28
Displays the distance between the reference stopper 5 and the corner cube 15 based on the above information, and displays the calculated distance on the display unit 2.

In this embodiment, the corner cube 15 is installed at the tip of the base material 4 (on the side where the stopper 7 is provided), and the head part 3 is installed in the storage section 1. Good. That is, even if the head portion 3 is installed at the tip of the base material 4 and the corner cube 15 is arranged in the storage portion 1, the same effect can be obtained. In this embodiment, since the interferometer is downsized, the tape measure can be configured to a size that does not impair the convenience of the conventional tape measure.

[0012]

As described above, according to the present invention, since the measurement (length measurement) is performed by the interferometer using the interference of laser light, the measurement accuracy can be improved to about 0.01 mm.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a configuration of a head unit of the interferometer used in the examples.

[Explanation of symbols]

 1 Storage Part 2 Display Part 3 Interferometer Head Part 4 Base Material 5 Reference Stopper 6 Laser Light 7 Stopper 15 Corner Cube (Reflecting Means) 21 Semiconductor Laser (Light Source) 22 Optical Waveguide 24 Grating Mirror (Reference Reflecting Mirror) 25 Rod Lens ( Inhomogeneous lens) 26 Photodetection means (photodiode) 27 Substrate 28 Signal processing means

Claims (3)

[Claims] 1. A strip-shaped base material that can be wound, a reflection means provided at one end of the base material, a storage means for winding and storing the base material from the other end, and the reflection means provided in the storage means. An interferometer-type tape measure, comprising: an interferometer head section for measuring a distance from the interferometer. 2. A strip-shaped base material which can be wound up, storage means for winding and storing the base material from one end, reflection means provided in the storage means, and the reflection means provided at the other end of the base material. An interferometer-type tape measure, comprising: an interferometer head section for measuring a distance from the interferometer. 3. A light source, an optical waveguide, a reference reflecting mirror, a light detecting means, wherein the interferometer head portion is integrally formed on a substrate,
3. An interferometric tape measure according to claim 1 or 2, further comprising a signal processing means, and an interferometer comprising the reflecting means.