JPH08152475A - Modulated-laser doppler speedometer - Google Patents

Modulated-laser doppler speedometer

Info

Publication number
JPH08152475A
JPH08152475A JP33131894A JP33131894A JPH08152475A JP H08152475 A JPH08152475 A JP H08152475A JP 33131894 A JP33131894 A JP 33131894A JP 33131894 A JP33131894 A JP 33131894A JP H08152475 A JPH08152475 A JP H08152475A
Authority
JP
Japan
Prior art keywords
frequency
doppler
laser
modulated
transition
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP33131894A
Other languages
Japanese (ja)
Inventor
Motoharu Jinguji
元治 神宮司
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to JP33131894A priority Critical patent/JPH08152475A/en
Publication of JPH08152475A publication Critical patent/JPH08152475A/en
Pending legal-status Critical Current

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Abstract

PURPOSE: To obtain a modulated-laser Doppler speedometer which can be miniaturized and whose application range is expanded by intensity-modulating a laser beam at a high frequency so as to be cast on a moving object and heterodyne-detecting reflected waves which have been returned and a reference signal. CONSTITUTION: A laser beam is intensity-modulated at a reference signal frequency (p) which is transmitted by an oscillator, and it is transmitted (an injection current is modulated by a semiconductor laser) so as to be cast on a target (a moving object). In reflected waves which has been returned, two Doppler frequency transitions are generated by the movement of the target with reference to the intensity-modulated laser beam. One is a Doppler frequency transition Δω generated by the frequency ω of the laser itself (as a carrier), and the other is a Doppler frequency transition Δp generated by a modulation signal (at a frequency (p)). Out of them, p+Δp is detected by a detector, a heterodyne detection is performed by a mixer between it and the reference signal (p), the frequency transition Δp is detected, and the speed of the target is found.

Description

【発明の詳細な説明】Detailed Description of the Invention

【0001】[0001]

【産業上の利用分野】本発明は、小型でシンプルなレー
ザドップラー速度計であり、プラント内のプロセス制御
や各種の工業的・環境計測的な用途において幅広い応用
分野が期待できる。
BACKGROUND OF THE INVENTION The present invention is a small and simple laser Doppler velocimeter, and can be expected to have a wide range of fields of application in process control in plants and various industrial and environmental measurement applications.

【0002】[0002]

【従来の技術】従来用いられてきたレーザドップラー速
度計は、レーザを基準光と送信光との2つに分けて照射
し、帰ってきた反射光の遷移周波数を反射光と基準光と
のヘテロダイン検波によって求めるものであった。従来
のレーザドップラー速度計は、レーザ自体の移動物体に
よるドップラー周波数遷移を利用するため、非常に大き
なドップラー周波数遷移が生じ、低速度の移動物体にし
か適用できないという欠点があった。また、従来のレー
ザドップラー速度計は、周波数遷移を落とすために波長
の長い赤外レーザを用い、非常に扱いにくいものであっ
た。また、システムが光学的システムで構成されるため
に、非常に機器も複雑かつ高価なものであった。
2. Description of the Related Art A conventional laser Doppler velocimeter irradiates a laser by dividing it into two beams, a reference beam and a transmitted beam, and returns the transition frequency of the reflected beam to a heterodyne of the reflected beam and the reference beam. It was obtained by detection. The conventional laser Doppler velocimeter uses the Doppler frequency transition due to the moving object of the laser itself, and therefore has a drawback that a very large Doppler frequency transition occurs and it can be applied only to a low-speed moving object. Further, the conventional laser Doppler velocimeter uses an infrared laser having a long wavelength in order to drop the frequency transition, which is very difficult to handle. Moreover, since the system is composed of an optical system, the equipment is very complicated and expensive.

【0003】[0003]

【発明が解決しようとする課題】本発明は、光学的な構
成部分がほとんどないレーザドップラー速度計であり、
システムのほとんどが電子的な構成で成り立っているた
めに、かなりの小型化が期待できる。また、ドップラー
遷移周波数が、従来のものに比べてかなりの低周波にな
るために、高速度の物体の速度測定や、パソコンのA/
Dコンバータなどの比較的低速度のサンプラーによる測
定も可能である。さらに、可視・紫外域のレーザの適用
も可能であるため、エアロゾル等のミー散乱を利用して
空気の流れの測定など、従来にない幅広い適用範囲が期
待できる。
SUMMARY OF THE INVENTION The present invention is a laser Doppler velocimeter with few optical components,
Since most of the system is made up of electronic components, it can be expected to be considerably miniaturized. In addition, the Doppler transition frequency is considerably lower than that of the conventional one.
Measurement with a relatively low-speed sampler such as a D converter is also possible. Further, since visible / ultraviolet lasers can be applied, a wide range of unprecedented applications such as measurement of air flow using Mie scattering of aerosol can be expected.

【0004】[0004]

【課題を解決するための手段】従来のレーザドップラー
速度計は、レーザ自体の波動性によるドップラーシフト
を利用して、コヒーレントヘテロダイン検波よりドップ
ラー遷移周波数を検出するものであった。本発明では、
レーザに高周波の強度変調をかけて移動物体に照射し、
帰ってきた変調波と基準信号とをヘテロダイン検波する
ことによって移動物体のドップラー遷移周波数を検出す
る。
The conventional laser Doppler velocimeter detects the Doppler transition frequency from the coherent heterodyne detection by utilizing the Doppler shift due to the wave nature of the laser itself. In the present invention,
Irradiate a moving object by applying high-frequency intensity modulation to the laser,
The Doppler transition frequency of the moving object is detected by performing heterodyne detection on the returned modulated wave and the reference signal.

【0005】[0005]

【本発明の詳細な説明】本発明は、従来のレーザドップ
ラー速度計の優れた特徴を受け継ぎながら、その欠点を
緩和・克服することを目的に考案された新しいタイプの
レーザドップラー速度計である。
DETAILED DESCRIPTION OF THE INVENTION The present invention is a new type of laser Doppler velocimeter designed to alleviate and overcome the drawbacks of the conventional laser Doppler velocimeter while inheriting the excellent features thereof.

【0006】ドップラー効果の周波数遷移Δfは、移動
物体の速度をV、媒体の速度をcとするならば、(1)
式のように示される。 (1)式では、fは照射される電磁波の周波数である。
このように、ドップラー周波数遷移Δfは、照射される
レーザの周波数fによって決定される。
If the velocity of the moving object is V and the velocity of the medium is c, the frequency transition Δf of the Doppler effect is (1)
It is shown like the formula. In the equation (1), f is the frequency of the electromagnetic wave to be irradiated.
Thus, the Doppler frequency transition Δf is determined by the frequency f of the emitted laser.

【0007】従来型のレーザドップラー速度計の概念図
を図1に示す。図1を見ても分かるように従来型のレー
ザドップラー速度計は、レーザ自体の移動物体によるド
ップラー遷移周波数を利用して移動物体の速度を計測し
ている。
A conceptual diagram of a conventional laser Doppler velocimeter is shown in FIG. As can be seen from FIG. 1, the conventional laser Doppler velocimeter measures the velocity of a moving object using the Doppler transition frequency of the moving object of the laser itself.

【0008】図2に示したのが、本発明の変調レーザド
ップラー速度計の概念図である。本発明では、従来のレ
ーザドップラー速度計とは異なり、レーザ自体の周波数
によるドップラー遷移周波数を利用するのではなく、レ
ーザに特定の周波数の高周波の強度変調をかけ、その反
射信号と基準信号とをヘテロダイン検波することによっ
て対象の移動速度を測定する。
FIG. 2 is a conceptual diagram of the modulated laser Doppler velocimeter of the present invention. In the present invention, unlike the conventional laser Doppler velocimeter, rather than utilizing the Doppler transition frequency due to the frequency of the laser itself, the laser is subjected to high-frequency intensity modulation of a specific frequency, and its reflected signal and reference signal are The speed of movement of the object is measured by heterodyne detection.

【0009】本発明は、変調波のドップラー効果を利用
している。図3に示したのがドップラー効果を受けた強
度変調波である。図3のOriginalと示したもの
が、ドップラー効果を受けていない送信波であり、Co
mpressedで示されたものがドップラーシフトを
受けた反射波である。図3中のp及びωは変調波及びレ
ーザ(搬送波)の周波数である。このp及びωは、移動
物体によってドップラー効果を受け、Δp及びΔωだけ
のドップラーシフトを受ける。この、Δp及びΔωのド
ップラーシフトは、p及びωによって決定され、その値
は(2)式及び(3)式に示される。 変調レーザドップラー速度計では、(2)式で示される
強度変調信号のドップラーシフトΔpを利用することに
よって、移動物体の速度を求める。また、(3)式のよ
うにレーザのドップラーシフトによる周波数遷移もまた
起きるが、光エネルギーを感知する光検出器に対して、
この程度のドップラーシフトは全く影響しない。むしろ
従来のレーザドップラー速度計のヘテロダイン検波のよ
うに、ターゲット以外の反射光に非常に強い戻り光が存
在した場合によって生じる干渉ビートが問題である。し
かしながら、干渉によって生じるビート周波数Δωは、
Δpに比べてかなりの高周波となるため、低域通過フィ
ルターによってカットすることが可能であると考えられ
る。
The present invention utilizes the Doppler effect of modulated waves. FIG. 3 shows the intensity-modulated wave that has undergone the Doppler effect. What is shown as “Original” in FIG. 3 is a transmitted wave that is not subjected to the Doppler effect,
What is expressed as pressed is the reflected wave that has undergone the Doppler shift. In FIG. 3, p and ω are frequencies of the modulation wave and the laser (carrier wave). The p and ω are subjected to the Doppler effect by the moving object, and are subjected to the Doppler shifts of Δp and Δω. The Doppler shifts of Δp and Δω are determined by p and ω, and their values are shown in equations (2) and (3). In the modulated laser Doppler velocimeter, the velocity of the moving object is obtained by utilizing the Doppler shift Δp of the intensity modulation signal shown by the equation (2). In addition, frequency transition due to the Doppler shift of the laser also occurs as in equation (3), but for the photodetector that senses light energy,
This degree of Doppler shift has no effect. Rather, as in the case of the heterodyne detection of the conventional laser Doppler velocimeter, the interference beat generated when the reflected light other than the target has a very strong returning light is a problem. However, the beat frequency Δω caused by the interference is
Since the frequency is considerably higher than Δp, it is considered possible to cut with a low-pass filter.

【0010】[0010]

【発明の効果】以上に述べてきたように本発明は、強度
変調信号のドップラー遷移周波数を利用するため、検出
されるドップラー遷移周波数を低周波にすることがで
き、また従来のレーザードップラー速度計での適用が困
難であった可視・紫外域での適用が可能である。また、
システムが電子的なシステムで構成されるために小型化
が容易である。
As described above, according to the present invention, since the Doppler transition frequency of the intensity modulation signal is used, the detected Doppler transition frequency can be made low, and the conventional laser Doppler velocimeter can be used. It can be applied in the visible / ultraviolet range, which was difficult to apply in Japan. Also,
Since the system is an electronic system, miniaturization is easy.

【手続補正書】[Procedure amendment]

【提出日】平成7年3月24日[Submission date] March 24, 1995

【補正対象書類名】明細書[Document name to be amended] Statement

【補正対象項目名】図面の簡単な説明[Name of item to be corrected] Brief description of the drawing

【補正方法】変更[Correction method] Change

【補正内容】[Correction content]

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

【図1】 平面図 従来型のレーザドップラー速度計の概念図である。従来
のレーザドップラー速度計は,レーザ光(キャリア)の
周波数fのドップラー遷移によって生じるΔfを光学的
なヘテロダイン検波によって検出し,その遷移周波数Δ
fよりターゲットの速度を測定するものであった。
FIG. 1 is a plan view of a conventional laser Doppler velocimeter. A conventional laser Doppler velocimeter detects Δf caused by Doppler transition of a frequency f of laser light (carrier) by optical heterodyne detection, and determines the transition frequency Δf.
The speed of the target was measured from f.

【符号の説明】 f :レーザ(キャリア)の周波数 Δf:ドップラー効果によって生じる遷移周波数[Explanation of symbols] f: Frequency of laser (carrier) Δf: Transition frequency caused by Doppler effect

【図2】平面図 本発明による変調ドップラー速度計の概念図である。本
発明では,Osillatorで発信させた基準信号周
波数pによって,レーザ光を強度変調させて送信する
(半導体レーザでは注入電流を制御する)。強度変調さ
れたレーザ光に対して,ターゲットの動きによって二つ
のドップラー周波数遷移が起こる。一つは,レーザ(キ
ャリア)自身の周波数ωによって生じるドップラー周波
数遷移Δωであり,もう一つは変調信号(周波数p)に
よって生じるドップラー周波数Δpである。このうちp
+Δpを Detectorによって検出し(ω+Δω
は周波数が高いために微弱であると考えられるが,ロー
パスフィルターによって除去することも可能であ
る。),Mixerにおいて基準信号pとの間でヘテロ
ダイン検波を行うことによってΔpを検出する。このΔ
pよりターゲットの速度を求める
FIG. 2 is a plan view of a modulated Doppler velocimeter according to the present invention. In the present invention, the laser light is intensity-modulated and transmitted by the reference signal frequency p transmitted by the oscillator (the injection current is controlled in the semiconductor laser). For the intensity-modulated laser light, two Doppler frequency transitions occur due to the movement of the target. One is the Doppler frequency transition Δω generated by the frequency ω of the laser (carrier) itself, and the other is the Doppler frequency Δp generated by the modulation signal (frequency p). Of these, p
+ Δp is detected by the Detector (ω + Δω
Is considered to be weak due to its high frequency, but it can be removed by a low-pass filter. ), And the Mixer performs heterodyne detection with the reference signal p to detect Δp. This Δ
Calculate the target speed from p

【符号の説明】 p :基準信号の周波数 ω :レーザ(キャリア)の周波数 Δp:変調信号のドップラー遷移周波数 Δω:レーザ(キャリア)のドップラー遷移周波数[Explanation of Codes] p: Frequency of reference signal ω: Frequency of laser (carrier) Δp: Doppler transition frequency of modulation signal Δω: Doppler transition frequency of laser (carrier)

【図3】平面図 変調波のドップラー遷移周波数の概念図である。上のC
ompressedは,ドップラーシフトによって周波
数遷移をうけた変調波の波形である。Original
(元々の変調波)の波形に比べて,キャリアはΔω,変
調信号はΔpだけ周波数が遷移している。各々のドップ
ラー遷移周波数はキャリア及び変調信号の周波数ω及び
pに依存している。
FIG. 3 is a plan view showing a conceptual diagram of a Doppler transition frequency of a modulated wave. Upper C
“Ompressed” is the waveform of a modulated wave that has undergone frequency transition due to Doppler shift. Original
Compared with the waveform of the (original modulated wave), the carrier has a frequency of Δω and the modulated signal has a frequency of Δp. Each Doppler transition frequency depends on the frequencies ω and p of the carrier and modulation signals.

【符号の説明】 V :ターゲットの速度 c :光速度 p :変調信号の周波数 ω :レーザ(キャリア)の周波数 Δp:変調信号のドップラー遷移周波数 Δω:レーザ(キャリア)のドップラー遷移周波[Explanation of Codes] V: Velocity of target c: Light velocity p: Frequency of modulation signal ω: Frequency of laser (carrier) Δp: Doppler transition frequency of modulation signal Δω: Doppler transition frequency of laser (carrier)

Claims (1)

【特許請求の範囲】[Claims] 【請求項1】 レーザ光に特定の周波数の強度変調をか
けて移動物体に照射し、その帰ってきた反射信号のドッ
プラー遷移周波数を基準信号との間のヘテロダイン検波
によって検出し、その遷移周波数より移動物体の速度を
測定する遠隔速度計測装置。
1. A laser light is intensity-modulated at a specific frequency to irradiate a moving object, and the Doppler transition frequency of the returning reflected signal is detected by heterodyne detection between the reference signal and the transition frequency. A remote speed measuring device that measures the speed of a moving object.
JP33131894A 1994-11-29 1994-11-29 Modulated-laser doppler speedometer Pending JPH08152475A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP33131894A JPH08152475A (en) 1994-11-29 1994-11-29 Modulated-laser doppler speedometer

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP33131894A JPH08152475A (en) 1994-11-29 1994-11-29 Modulated-laser doppler speedometer

Publications (1)

Publication Number Publication Date
JPH08152475A true JPH08152475A (en) 1996-06-11

Family

ID=18242351

Family Applications (1)

Application Number Title Priority Date Filing Date
JP33131894A Pending JPH08152475A (en) 1994-11-29 1994-11-29 Modulated-laser doppler speedometer

Country Status (1)

Country Link
JP (1) JPH08152475A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108430324A (en) * 2015-11-24 2018-08-21 威里利生命科学有限责任公司 The system and method for real time laser doppler imaging
CN111562081A (en) * 2020-04-30 2020-08-21 成都英鑫光电科技有限公司 Flow field testing method and device, electronic equipment and computer readable storage medium

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108430324A (en) * 2015-11-24 2018-08-21 威里利生命科学有限责任公司 The system and method for real time laser doppler imaging
CN111562081A (en) * 2020-04-30 2020-08-21 成都英鑫光电科技有限公司 Flow field testing method and device, electronic equipment and computer readable storage medium

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