JP3619851B2 - A method of improving the accuracy of a straight line meter using a laser beam. - Google Patents

Description

【０００８】
こゝでＫの値は、一般に定数であると考えられるが、測定環境によって幾分異なるので、最初の２０点のデータを用いた回帰分析の方法によって計算される。
【０００９】
しかし、この２色法は、大気のゆらぎによるレーザビームのゆらぎ度を検出して直線位置Ｐの測定精度の向上を図ることができるが、上記の他の原因によるゆらぎを解消するには充分ではない。
【００１０】
【発明が解決しようとする課題】
本発明が解決しようとする課題は、上記の他の原因によるレーザビームのゆらぎの問題をも解消し、且つ真の直線位置がある方向を知ることができる一手法を提案し、高精度の直線計を提供することを課題とするものである。
【００１１】
【課題を解決するための手段】
本発明は、基本波λ１と第２高調波λ２の２波長レーザを交互に出射する光源装置と、レーザビームを受光する位置センサとを備え、該位置センサの検出値をコンピュータによって演算処理して直線位置を求める直線計において、位置センサとしてデジタイザー又はＣＣＤカメラを用い、且つ前記光源装置から出射するレーザビームを回転させるようにし、コンピュータは、各計測角毎に前記位置センサによって検出したレーザビーム受光位置の座標値からλ１の検出点サークルの中心位置０１とλ２の検出点サークルの中心位置０２を求め、これら両中心位置０１，０２から真の直線位置がある方向と直線位置を演算するようにしたものである。
【００１２】
図２は本発明の原理説明図で、λ１，λ２の波長のレーザビームを交互に発射させると共に回転させ、デジタイザー又はＣＣＤカメラから成る位置センサ２にレーザビームを投射し、各回転位置における座標を検出し、その検出値から各検出点サークルＣ１（λ１レーザビームによるもの）と検出点サークルＣ２（λ２レーザビームによるもの）のそれぞれの幾何学的中心位置０１，０２を演算（統計処理）によって求め、この中心位置０１，０２から、更に前述の式（Ｐ１を０１，Ｐ２を０２と読み替える）によって演算し、真の直線位置Ｐ及び真の直線位置Ｐがある方向を求めるものである。
【００１３】
なお、説明の便宜上、図２では検出点サークルＣ１，Ｃ２を真円で表現したが、実際には少しゆがんだものとなることは勿論である。
【００１４】
【作用】
本発明によると、光路途中にある媒質によるゆらぎのみならず、他の原因によるゆらぎによるλ１，λ２レーザビームのゆらぎ度を検出し、このゆらぎ度から統計的演算により真の直線位置がある方向と直線位置を高精度で検出することができる。
【００１５】
【発明の実施の形態】
図３は本発明の一実施例のブロック図で、１光源装置、２はＣＣＤカメラを用いた位置センサ、３は駆動装置、４は信号処理回路、５はパーソナル・コンピュータである。
【００１６】
光源装置１はＬＤ励起ＹＡＧの１．０６μｍ（λ１）とこの波長を基本波とする２次高調波５３２ｎｍ（λ２）のレーザを交互に出射するもので、出射レーザは波長選択素子６、レンズ７、光ファイバ８、レンズ９及び出射レーザビーム回転用の光路変更光学装置１０を介して位置センサ２に向けて出射される。
【００１７】
出射レーザビーム回転用の光路変更光学装置１０は、λ１，λ２のレーザビームを回転させるもので、実施例では適当な厚さのガラス板を適当な角度に設け、１分間に２５５ステップで１回転させるステッピングモータ１１によってこのガラス板を軸中心に回転させるようにしたものであるが他の構造であってもよい。
【００１８】
例えば、ＸスキャンヘッドとＹスキャンヘッドを備えた公知のガルバノメータ・スキャナーを用い、それを駆動装置３によって駆動して出射レーザビームを回転させる構成を採ってもよい。
【００１９】
信号処理回路４では、位置センサ２で検出した２５５点の各λ１レーザとλ２レーザの検出点の座標から、前記検出点サークルＣ１，Ｃ２のそれぞれの中心位置０１，０２を統計的処理により演算し、パーソナルコンピュータ４はその値から真の直線位置０の方向を求めると共に、２色法による計算式によりλ１とλ２の中心位置０１，０２から真の位置までの距離を求める。
【００２０】
従来の２色直線計は１点での検出値により真の直線位置を算出するものであったが、本発明では多点の検出値に基づいて真の直線位置をさ算出するものであるから測定精度は一層高精度のものとなる。
【００２１】
【発明の効果】
本発明によれば、従来の２色直線計では補正し得なかった他の原因による誤差をも除去することができ、高精度の直線計を提供することが出来る。
【図面の簡単な説明】
【図１】レーザビーム位置の大気によるゆらぎを補正する２色直線計の原理を示す説明図である。
【図２】本発明の原理を説明する説明図である。
【図３】本発明の実施例のブロック図である。
【符号の説明】
１ 光源装置
２ 位置センサ
３ 駆動装置
４ 信号処理回路
５ パーソナル・コンピュータ
６ 波長選択素子
７，９ レンズ
８ 光ファイバ
１０ 光路変更光学装置
１１ ステッピングモータ[0001]
BACKGROUND OF THE INVENTION
The present invention is a straight line using a laser beam used for measuring straightness and verticality of a high-rise building, or arranging an object in a straight line when a large structure is formed, or examining the flatness of the object. The present invention relates to a method for improving the accuracy of the meter.
[0002]
[Prior art]
As is well known, the straightness of the laser beam and in-plane displacement (displacement perpendicular to the laser beam propagation direction) and straightness measurement using a semiconductor position sensor and straightness measurement can be easily performed anywhere. It is widely used because it can measure the standard.
[0003]
In recent research, a measurement example of an optical path length (distance until the laser beam emitted from the laser device enters the position detector) of 100 m and a resolution of several nm has been reported.
[0004]
However, this method has a drawback that the measurement accuracy deteriorates as the optical path length increases because the laser beam that should be a linear reference fluctuates.
[0005]
The cause of the fluctuation of the laser beam is mainly due to a change in the refractive index of a medium (generally air) in the middle of the optical path. Other causes include a change in the emission direction of the laser beam caused by thermal deformation of the laser device and vibration. When the position sensor is attached to the building, the vibration is considered as a cause.
[0006]
Conventionally, the two-color method is known for the fluctuation of the laser beam due to the air fluctuation (change in the refractive index of air) which is the main cause of the fluctuation of the laser beam. In this two-color method, two-color laser beams of a fundamental wave λ1 and a second harmonic λ2 are alternately emitted as a light source, a quadrant position sensor is used as a linear position sensor PSD, and as shown in FIG. It is detected that the degree of fluctuation is different from P1 and P2, and an ideal straight line position P is estimated by the following equation using a personal computer.
[0007]
[Expression 1]

[0008]
Here, the value of K is generally considered to be a constant. However, since it varies somewhat depending on the measurement environment, it is calculated by the method of regression analysis using the data of the first 20 points.
[0009]
However, this two-color method can detect the degree of fluctuation of the laser beam due to atmospheric fluctuations and improve the measurement accuracy of the linear position P. However, this two-color method is not sufficient to eliminate fluctuations due to the above other causes. Absent.
[0010]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to solve the problem of fluctuation of the laser beam due to the above-mentioned other causes and propose a method capable of knowing the direction in which the true straight line is located, and to provide a highly accurate straight line. The challenge is to provide a total.
[0011]
[Means for Solving the Problems]
The present invention includes a light source device that alternately emits two-wavelength lasers of the fundamental wave λ1 and the second harmonic λ2, and a position sensor that receives the laser beam, and the detection value of the position sensor is processed by a computer. In a linear meter for determining a linear position, a digitizer or a CCD camera is used as a position sensor, and the laser beam emitted from the light source device is rotated. The computer receives the laser beam detected by the position sensor at each measurement angle. From the coordinate values of the positions, the center position 01 of the detection point circle of λ1 and the center position 02 of the detection point circle of λ2 are obtained, and a direction and a straight line position with a true straight line position are calculated from these center positions 01 and 02. It is a thing.
[0012]
FIG. 2 is a diagram for explaining the principle of the present invention. Laser beams having wavelengths of λ1 and λ2 are alternately emitted and rotated, and the laser beam is projected onto a position sensor 2 composed of a digitizer or a CCD camera. Then, the geometric center positions 01 and 02 of each detection point circle C1 (by the λ1 laser beam) and detection point circle C2 (by the λ2 laser beam) are obtained by calculation (statistical processing) from the detected value. From the center positions 01 and 02, the calculation is further performed by the above-described formula (P1 is read as 01 and P2 as 02), and the true straight line position P and the true straight line position P are obtained.
[0013]
For convenience of explanation, the detection point circles C1 and C2 are represented by perfect circles in FIG. 2, but it is a matter of course that the detection point circles C1 and C2 are actually slightly distorted.
[0014]
[Action]
According to the present invention, not only the fluctuation caused by the medium in the optical path but also the fluctuation degree of the λ1, λ2 laser beam due to the fluctuation caused by other causes is detected, and the true linear position is determined from the fluctuation degree by statistical calculation. The straight line position can be detected with high accuracy.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 3 is a block diagram of an embodiment of the present invention. One light source device, 2 is a position sensor using a CCD camera, 3 is a driving device, 4 is a signal processing circuit, and 5 is a personal computer.
[0016]
The light source device 1 alternately emits a laser of 1.06 μm (λ1) of LD excitation YAG and a second-order harmonic of 532 nm (λ2) having this wavelength as a fundamental wave. The emitted laser is a wavelength selection element 6 and a lens 7. The light is emitted toward the position sensor 2 through the optical fiber 8, the lens 9, and the optical path changing optical device 10 for rotating the emitted laser beam.
[0017]
The optical path changing optical device 10 for rotating the outgoing laser beam rotates the laser beam of λ1 and λ2, and in the embodiment, a glass plate having an appropriate thickness is provided at an appropriate angle and rotated once in 255 steps per minute. The glass plate is rotated about the axis by the stepping motor 11 to be used, but other structures may be used.
[0018]
For example, a known galvanometer scanner provided with an X scan head and a Y scan head may be used, and the output laser beam may be rotated by driving it with the driving device 3.
[0019]
In the signal processing circuit 4, the center positions 01 and 02 of the detection point circles C 1 and C 2 are calculated by statistical processing from the coordinates of the detection points of 255 λ1 lasers and λ2 lasers detected by the position sensor 2. The personal computer 4 obtains the direction of the true straight line position 0 from the value, and obtains the distance from the center positions 01 and 02 of the λ1 and λ2 to the true position by the calculation formula by the two-color method.
[0020]
The conventional two-color straight line meter calculates the true straight line position based on the detection value at one point. However, in the present invention, the true straight line position is calculated based on the detection values at multiple points. The measurement accuracy is higher.
[0021]
【The invention's effect】
According to the present invention, it is possible to eliminate errors caused by other causes that could not be corrected by the conventional two-color linear meter, and to provide a highly accurate linear meter.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing the principle of a two-color linear meter that corrects fluctuations of the laser beam position due to the atmosphere.
FIG. 2 is an explanatory diagram illustrating the principle of the present invention.
FIG. 3 is a block diagram of an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Light source device 2 Position sensor 3 Drive apparatus 4 Signal processing circuit 5 Personal computer 6 Wavelength selection element 7, 9 Lens 8 Optical fiber 10 Optical path changing optical apparatus 11 Stepping motor

Claims (2)

A light source device that alternately emits two-wavelength lasers of the fundamental wave λ1 and the second harmonic λ2 and a position sensor that receives the laser beam are provided, and a detection value of the position sensor is processed by a computer to obtain a linear position. In a linear meter, a digitizer or a CCD camera is used as a position sensor and the laser beam emitted from the light source device is rotated. The computer detects the coordinate value of the laser beam receiving position detected by the position sensor at each measurement angle. The center position 01 of the detection point circle of λ1 and the center position 02 of the detection point circle of λ2 are obtained, and the direction of the true straight line position and the straight line position are calculated from these center positions 01 and 02. A method for improving the accuracy of a straight line meter using a characteristic laser beam. 2. The method for improving the accuracy of a linear meter using a laser beam according to claim 1, wherein an optical device for changing the optical path is disposed in front of the laser beam exit of the light source device.

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