JPS62156563A - Measuring device for speed and distance - Google Patents

Abstract

PURPOSE:To measure simultaneously and with a high accuracy a moving speed of a measuring object and a distance to the measuring object, by providing an arithmetic part, and an optical system for generating two kinds of irradiating light beams whose waist position is shifted and also whose irradiating areas to the measuring object become the same on a projecting part. CONSTITUTION:A projecting part 1 generates a speckle pattern by projecting a coherent light to a moving measuring object 4, and constituted of a laser light source 5, and an optical system 9 for generating the first and the second irradiating light beams 7, 8 from a laser light 6 which the laser light source 5 is radiated and irradiating them to the measuring object 4. The first and the second irradiating lights 7, 8 are shifted as to beam waist positions W1, W2, respectively, and also have the same irradiating area against the measuring object 4. The first irradiating light 7 and the second irradiating light 8 are generated by the first optical system 9A and the second optical system 9B, respectively. An arithmetic part 3 calculates a moving speed (v) of the measuring object 4 and a distance R to the measuring object 4 by deriving a mutual correlation value of a speckle signal which has been obtained by each photodetecting part 2A, 2B.

Description

【発明の詳細な説明】 〈発明の技術分野〉 この発明は、移動する測定対象ヘレーザ光のようなコヒ
ーレントな光を照射し、この測定対象の粗表面で光を散
乱させて、光のランダム干渉パターン（以下、これを「
スペックルパターン」という）を生成し、このスペック
ルパターンの動的特性から測定対象の移動速度と測定対
象までの距離とを同時に測定する速度および距離測定装
置に関する。[Detailed Description of the Invention] <Technical Field of the Invention> The present invention irradiates a moving measurement target with coherent light such as laser light, scatters the light on the rough surface of the measurement target, and generates random interference of light. pattern (hereinafter referred to as ``
The present invention relates to a speed and distance measuring device that generates a speckle pattern (referred to as a "speckle pattern") and simultaneously measures the moving speed of an object to be measured and the distance to the object from the dynamic characteristics of this speckle pattern.

〈発明の背景〉 先般、移動する物体の速度とその物体までの距離とを同
時に測定する装置として、第３図に示す構成の装置が提
案された（電気通信学会論文誌、　１９８４／　１　）
。この装置は、レーザ光２１ヲ光フアイバ２２により測
定点２３へ導いてスペックルパターンを生成し、このス
ペックルパターンの移動を異なる位置に配置された２徂
の光ファイバ列空間フィルタ２４．２５を用いて検出す
る方式のものである。ところがこの方式の装置の場合、
スペックルパターンは光ファイバ列空間フィルタ２４．
２５を経て検出されるため、検出信号のＳＮ比が悪く、
測定精度が低下するという欠点がある。また前記光ファ
イバ列空間フィルタ２４．２５を構成するのに複数本の
光ファイバを直線状に実装する必要があるが、この種の
実装は容易でなく、装置のコスト高を招くばかりでなく
、光フアイバ列の直線性が悪いと、空間フィルタのＱ（
出力信号の選択度）が低下して、測定精度の低下を招い
ている。<Background of the Invention> Recently, a device having the configuration shown in Figure 3 was proposed as a device for simultaneously measuring the speed of a moving object and the distance to the object (Transactions of the Institute of Electrical Communication Engineers, 1984/1).
. This device generates a speckle pattern by guiding a laser beam 21 to a measurement point 23 by an optical fiber 22, and moves the speckle pattern by using two optical fiber array spatial filters 24 and 25 placed at different positions. This is a detection method using However, in the case of this type of device,
The speckle pattern is generated by the optical fiber array spatial filter 24.
25, the S/N ratio of the detection signal is poor;
There is a drawback that measurement accuracy is reduced. Furthermore, in order to construct the optical fiber array spatial filters 24 and 25, it is necessary to mount a plurality of optical fibers in a straight line, but this kind of mounting is not easy and not only increases the cost of the device, but also If the linearity of the optical fiber array is poor, the Q(
The selectivity of the output signal decreases, leading to a decrease in measurement accuracy.

さらに光ファイバのコア径、配列ピッチおよびスペック
ルサイズの関係は、前記のＱが最大となるよう設定する
必要があり、光学的条件が厳しくなるばかりでなく、も
し設定ずれがあると、測定精度を低下させる要因となる
。さらにまた、測定対象の粗表面の性状によりスペック
ルパターンの形や大きさが変化すると、前記のＱが変化
して測定精度に悪影響を及ぼす等、多くの問題がある。Furthermore, the relationship between the optical fiber core diameter, array pitch, and speckle size must be set so that the above-mentioned Q is maximized. Not only will the optical conditions become stricter, but if there are any deviations in the settings, measurement accuracy will be affected. This is a factor that reduces the Furthermore, if the shape or size of the speckle pattern changes depending on the properties of the rough surface of the object to be measured, there are many problems such as the above-mentioned Q changes and adversely affects measurement accuracy.

〈発明の目的〉 この発明は、上記問題を解消するためのものであって、
測定対象の移動速度と測定対象までの距離とを同時且つ
高精度に測定できる新規な速度および距離測定装置を提
供することを目的とする。<Object of the invention> This invention is intended to solve the above problems,
It is an object of the present invention to provide a novel speed and distance measuring device that can simultaneously and highly accurately measure the moving speed of a measurement target and the distance to the measurement target.

〈発明の構成および効果〉 上記目的を達成するため、この発明では、移動する測定
対象ヘコヒーレントな光を照射してスペックルパターン
を生成するための投光部と、測定対象からの反射光また
は透過光を受光してスペックル信号を得るための所定距
離隔てて配備された一対の受光部と、それぞれ受光部で
得たスペックル信号の相互相関値を求めて測定対象の移
動速度および測定対象までの距離を算出する演算部とで
速度および距離測定装置を形成し、前記投光部には、ウ
ェスト位置がずれ且つ測定対象への照射領域が同一とな
る２種の照射光を生成する光学系を設けることにした。<Configuration and Effects of the Invention> In order to achieve the above object, the present invention includes a light projecting section for generating a speckle pattern by irradiating a moving measurement object with coherent light, and a light emitting section for generating a speckle pattern by irradiating a moving measurement object with coherent light; A pair of light receiving sections are placed at a predetermined distance apart to receive transmitted light and obtain speckle signals, and the cross-correlation value of the speckle signals obtained by each light receiving section is calculated to determine the moving speed of the object to be measured and the measurement object. A speed and distance measuring device is formed with a calculation unit that calculates the distance to I decided to set up a system.

この発明によれば、スペックルパターンは従来例のよう
に光ファイバ等を中間に介在させずに直接受光部にて検
出するから、検出信号のＳＮ比が良好であり、測定精度
が向上する。またこの発明の装置の場合、光ファイバ列
空間フィルタを用いた従来例と比較して、光学系の組立
てや設定がきわめて容易であり且つ測定精度を低下させ
る要因が少なく、さらに波形相関計測方式であるから、
測定対象の粗表面の性状によりスペックルパターンの形
や大きさが変化しても、測定精度に悪影響を受けない等
、発明目的を達成した顕著な効果を奏する。According to this invention, the speckle pattern is detected directly by the light receiving section without intervening an optical fiber or the like as in the conventional example, so that the S/N ratio of the detection signal is good and the measurement accuracy is improved. In addition, in the case of the device of the present invention, compared to the conventional example using an optical fiber array spatial filter, the assembly and setting of the optical system is extremely easy, there are fewer factors that reduce measurement accuracy, and furthermore, it is possible to use the waveform correlation measurement method. because there is,
Even if the shape and size of the speckle pattern change depending on the properties of the rough surface of the object to be measured, the measurement accuracy is not adversely affected, and the object of the invention is achieved.

〈実施例の説明〉 第１図は、この発明にかかる速度および距離測定装置の
一実施例を示すもので、図示例の装置は、投光部１、一
対の受光部２Ａ、２Ｂおよび、演算部３より構成されて
いる。<Description of Embodiment> FIG. 1 shows an embodiment of the speed and distance measuring device according to the present invention. It consists of part 3.

投光部１は、移動する測定対象４に対しコヒーレントな
光を投射して、スペックルパターンを生成するためのも
ので、図示例の場合、レーザ光源５と、このレーザ光源
５が放射したレーザ光６より第１．第２の照射光７．８
を生成して測定対象４へ照射させるための光学系９とか
ら構成される。前記第１．第２の各照射光７゜８は、ビ
ームウェスト位置Ｗ、、Ｗ２がずれ且つ測定対象４に対
し同一の照射領域を有するものであって、第１の照射光
７は、第１ビームスプリツタ１０、収束レンズ１１およ
び第２ビームスプリツタ１２より成る第１光学系９Ａで
生成され、また第２の照射光８は、第１ビームスプリッ
タ１０１２個の反射鏡１３．１４、収束レンズ１５およ
び、第２ビームスプリツタ１２より成る第２光学系９Ｂ
で生成される。The light projecting unit 1 is for projecting coherent light onto a moving measurement target 4 to generate a speckle pattern, and in the illustrated example, a laser light source 5 and the laser emitted by the laser light source 5 1st from light 6. Second irradiation light 7.8
and an optical system 9 for generating and irradiating it onto the measurement target 4. Said 1st. The second irradiation lights 7°8 have shifted beam waist positions W, , W2 and have the same irradiation area with respect to the measurement object 4, and the first irradiation lights 7 have the same irradiation area with respect to the measurement object 4. 10, a first optical system 9A consisting of a converging lens 11 and a second beam splitter 12, and the second irradiation light 8 is generated by the first beam splitter 10, 12 reflecting mirrors 13, 14, a converging lens 15, and Second optical system 9B consisting of second beam splitter 12
is generated.

受光部２Ａ、２Ｂは、測定対象４の粗表面で散乱した透
過光１６を、距離Ｘ離れた位置で受光して電気信号（ス
ペックル信号）に変換するためのもので、それぞれフォ
トダイオード１７゜１８と、各フォトダイオードの電流
比ノコ信号を電圧信号に変換するバッファアンプ１９．
２０とを含んでいる。The light receiving sections 2A and 2B are for receiving the transmitted light 16 scattered by the rough surface of the measurement object 4 at a distance X and converting it into an electric signal (speckle signal), and each has a photodiode 17°. 18, and a buffer amplifier 19 that converts the current ratio signal of each photodiode into a voltage signal.
20.

演算部３は、各受光部２Ａ、２Ｂで得たスペックル信号
の相互相関値を求めて測定対象４の移動速度Ｕおよび測
定対象４までの距離Ｒを算出するだめのものである。The calculation section 3 is used to calculate the moving speed U of the measurement object 4 and the distance R to the measurement object 4 by obtaining the cross-correlation value of the speckle signals obtained by each of the light receiving sections 2A and 2B.

しかしてレーザ光源５が駆動されると、レーザ光源５よ
りレーザ光６が出射され、光学系９により第１．第２の
各照射光７．８が生成されて、移動する測定対象４へ照
射される。これら照射光７．８は、測定対象４の粗表面
で散乱され、それぞれの透過光が空間に拡がる拡散光と
なってスペックルパターンが生成される。前記拡散光は
受光部２Ａ、２Ｂの各フォトダイオード１７．１８に入
射されて、電気信号（スペ・ノクル信号）に変換され、
さらにバッファアンプ１９．２０で電圧信号に変換され
て演算部３へ送られる。When the laser light source 5 is driven, a laser light 6 is emitted from the laser light source 5, and the first laser light 6 is emitted by the optical system 9. Second respective irradiation lights 7.8 are generated and irradiated onto the moving measurement object 4. These irradiated lights 7.8 are scattered by the rough surface of the measurement object 4, and each transmitted light becomes diffused light that spreads in space, thereby generating a speckle pattern. The diffused light is incident on each photodiode 17, 18 of the light receiving sections 2A, 2B, and is converted into an electric signal (spenocle signal),
Furthermore, it is converted into a voltage signal by buffer amplifiers 19 and 20 and sent to the calculation section 3.

ところで前記スペックルパターンは、測定対象４の粗表
面が移動すると、全体の並進運動（Ｔｒａｍｓｌａｔｉ
ｏｎ　）とボイリング運動（Ｂｏｉｌｉｎｇ）とを伴っ
て、時間的に変形ないしは移動する。By the way, when the rough surface of the measurement object 4 moves, the speckle pattern causes an overall translational movement (translational movement).
on ) and boiling motion, deforming or moving temporally.

従ってこの動的スペックルの場は時空間に関する確率過
程とみなされ、その定量的な評価には統計的解析、たと
えばスペックル場の時空間相関関数の解析が必要となる
。Therefore, this dynamic speckle field is regarded as a stochastic process related to space and time, and its quantitative evaluation requires statistical analysis, for example, analysis of the spatio-temporal correlation function of the speckle field.

そこで今、第２図に示す如く、ξη座標系で規定される
物体面と、この物体面と平行なｘｙ座標系で規定される
受光面とを想定し、物体が物体面内を速度／ｆ＜Ｉｌｌ
はベクトル＠）で運動したときの受光面上の点＆（％は
ベクトル量）における動的スペックル強度の時空間相関
関数を解析する。Now, as shown in Fig. 2, we assume an object plane defined by the ξη coordinate system and a light-receiving plane defined by the xy coordinate system parallel to this object plane, and the object moves in the object plane at a velocity/f. <Ill
Analyzes the spatio-temporal correlation function of the dynamic speckle intensity at the point & (% is the vector amount) on the light-receiving surface when moving with the vector @).

この測定系において、時間をτ、物体面と受光面との間
の距離をＲ１受光面上の２点仄、。In this measurement system, the time is τ, and the distance between the object surface and the light-receiving surface is R1 between two points on the light-receiving surface.

夙２の距離ベクトルを％：　（＝、＜ｚ　　＊ｔ　）　
、移動物体への照射光の半径をＷ、その波長をλ、光で
こ作用によるスペックル並進倍率をσ、照射光の波面曲
率をρとすると、動的スペックル強度ゆらぎの時空間相
関関数としてつぎの０式％式％ なおスペックル並進倍率σは、つぎの０式で定義される
。2nd distance vector as %: (=, <z *t)
, the radius of the irradiated light on a moving object is W, its wavelength is λ, the speckle translation magnification due to the optical lever action is σ, and the wavefront curvature of the irradiated light is ρ, then the spatiotemporal correlation function of dynamic speckle intensity fluctuation is The speckle translational magnification σ is defined by the following equation 0.

σ；□＋１　・・・・■ ρ 前記０式において、に＝０とすると、スペックル強度ゆ
らぎが、回折領域のある点で検出されだ場合の時間相関
関数が として得られる。ここでτ。は時間相関長であって、つ
ぎの０式で表わせる。σ; □+1 . . . ■ ρ In the above equation 0, if σ = 0, the time correlation function when speckle intensity fluctuation is detected at a certain point in the diffraction region is obtained as follows. Here τ. is the time correlation length and can be expressed by the following equation 0.

この０式かられかるように、時間相関長で。As can be seen from this equation 0, the time correlation length.

は物体速度０の大きさに逆比例し、その比例定数が平均
スペックル径ΔＸに依存し、さらに照射光の半径Ｗおよ
び波面曲率ρ（０式参照）に依存する。is inversely proportional to the magnitude of the object velocity 0, and its proportionality constant depends on the average speckle diameter ΔX, and further depends on the radius W and wavefront curvature ρ (see equation 0) of the irradiated light.

平均スペックル径ΔＸと時間相関長τ、は、動的スペッ
クル強度ゆらぎの時空間相関関数を特徴づける重要な統
計量であって、これらを用いて０式を書き換えることに
よって、つぎの０式を得る。The average speckle diameter ΔX and the temporal correlation length τ are important statistics that characterize the spatiotemporal correlation function of dynamic speckle intensity fluctuations, and by rewriting the equation 0 using these, the following equation 0 can be obtained. get.

Ｔａ１（％、　　ｒ）　＝ｅｘｐ　　（−（τ−τｄ）
２／　τ、′〕・・・・■ ここでτ６は距離ベクトルＸをもつ２点次、。Ta1 (%, r) = exp (-(τ-τd)
2/ τ,']...■ Here, τ6 is a two-point order with a distance vector X.

交２で検出されるスペックル強度の相互相関関数の遅れ
時間であって、つぎの０式で表される。This is the delay time of the cross-correlation function of the speckle intensity detected at intersection 2, and is expressed by the following equation.

τＣ′ τ４−□σＶ処　・・・・■ Δ　ｘ２ かくして距離ベクトル〆と速度ベクトルかとを同一方向
にとり且つ１％ｌ＝Ｘとするような測定系（具体的には
、第１図に示す測定系）を考えるとき、０式を０式へ代
入して０式を書き換えると、 となり、この点における０式の相関値はγΔＩ（メ、τ
） ・・・・■ となる。τC' τ4-□σV processing...■ Δ x2 Thus, a measurement system in which the distance vector and velocity vector are in the same direction and 1%l=X (specifically, the measurement shown in Fig. 1) is used. system), by substituting equation 0 into equation 0 and rewriting equation 0, we get, and the correlation value of equation 0 at this point is γΔI(me, τ
) ...■.

この０式のスペックル強度ゆらぎの相関関数を時間τの
関数として表すと、第３図に示すような相関ピーク値を
もつ特性図が得られる。If this correlation function of speckle intensity fluctuation of equation 0 is expressed as a function of time τ, a characteristic diagram having a correlation peak value as shown in FIG. 3 is obtained.

第１図に示す測定系の場合、ビームウェスト位置Ｗ、、
Ｗ２がずれ且つ測定対象４に対し同一の照射領域をもつ
２種の照射光７．８を用いているから、それぞれ照射光
７．８について、相関ピーク値のずれた相関特性ｍｉ、
ｍ２が得られる。In the case of the measurement system shown in Fig. 1, the beam waist position W,
Since two types of irradiation light 7.8 with different W2 and the same irradiation area for the measurement object 4 are used, for each irradiation light 7.8, correlation characteristics mi, with different correlation peak values, are used.
m2 is obtained.

令弟１の照射光７の波面曲率をρ１．第２の照射光８の
波面曲率をρ２とすると、前記の遅れ時間τ４４．τ、
２は００式よりつぎのように表される。Let the wavefront curvature of the irradiated light 7 of the younger brother 1 be ρ1. If the wavefront curvature of the second irradiation light 8 is ρ2, the delay time τ44. τ,
2 is expressed as follows from formula 00.

かくして演算部３では、いずれか遅れ時間〕 τ６．またはτ、２から■または［相］式を用いて速度
Ｕを算出する。さらに演算部３は、速度Ｖの算出値と遅
れ時間の差（τ４．−τ４□）とからつぎの０式を用い
て測定対象４までの距離Ｒを算出するものである。Thus, in the calculation unit 3, any delay time] τ6. Alternatively, calculate the speed U from τ, 2 using ■ or the [phase] formula. Further, the calculation unit 3 calculates the distance R to the measurement target 4 from the calculated value of the speed V and the difference in delay time (τ4.−τ4□) using the following equation.

【図面の簡単な説明】[Brief explanation of drawings]

第１図はこの発明の一実施例を示す概略構成を示す図、
第２図はこの発明の装置の原理を説明するための図、第
３図は相関特性を示す図、第４図は従来例の概略構成を
示す図である。FIG. 1 is a diagram showing a schematic configuration of an embodiment of the present invention;
FIG. 2 is a diagram for explaining the principle of the apparatus of the present invention, FIG. 3 is a diagram showing correlation characteristics, and FIG. 4 is a diagram showing a schematic configuration of a conventional example.

Claims (3)

【特許請求の範囲】[Claims] （１）移動する測定対象へコヒーレントな光を照射して
スペックルパターンを生成するための投光部と、測定対
象からの反射光または透過光を受光してスペックル信号
を得るための所定距離隔てて配備された一対の受光部と
、それぞれ受光部で得たスペックル信号の相互相関値を
求めて測定対象の移動速度および測定対象までの距離を
算出する演算部とから成り、前記投光部は、ウエスト位
置がずれ且つ測定対象への照射領域が同一となる２種の
照射光を生成する光学系を含んで成る速度および距離測
定装置。(1) A light projector for generating a speckle pattern by irradiating a moving measurement target with coherent light, and a predetermined distance for receiving reflected or transmitted light from the measurement target to obtain a speckle signal. It consists of a pair of light-receiving sections arranged apart from each other, and a calculation section that calculates the cross-correlation value of the speckle signals obtained by each light-receiving section and calculates the moving speed of the measurement object and the distance to the measurement object. A speed and distance measuring device comprising an optical system that generates two types of irradiation light whose waist positions are shifted and whose irradiation areas on a measurement target are the same. （２）前記投光部は、１個のレーザ光源より放射される
レーザ光を２つの光学系に分岐させて前記２種の照射光
を生成する特許請求の範囲第１項記載の速度および距離
測定装置。(2) The speed and distance according to claim 1, wherein the light projecting section branches laser light emitted from one laser light source into two optical systems to generate the two types of irradiation light. measuring device. （３）前記一対の各受光部には、それぞれフォトダイオ
ードが用いられている特許請求の範囲第１項記載の速度
および距離測定装置。(3) The speed and distance measuring device according to claim 1, wherein a photodiode is used in each of the pair of light receiving sections.