JP2004157044A

JP2004157044A - Scanning type laser radar

Info

Publication number: JP2004157044A
Application number: JP2002324094A
Authority: JP
Inventors: Osamu Shimizu; 修清水
Original assignee: Nippon Signal Co Ltd
Current assignee: Nippon Signal Co Ltd
Priority date: 2002-11-07
Filing date: 2002-11-07
Publication date: 2004-06-03

Abstract

<P>PROBLEM TO BE SOLVED: To widen a monitoring field of a scanning type laser radar which receives reflected light of scanning laser light with a different light path from that of the scanning laser light. <P>SOLUTION: Laser light from a laser light source 2 is scanned by a scanning mirror 4, the reflected light of which is received via a focusing lens 7 by an array of light receiving elements 8 on which a lot of the light receiving elements are arranged . A distance measuring controller 12 outputs a light receiving element selection order to a multiplexer 9 based on memory information of a conversion table memory 13 for each scanning position. According to the selection order the multiplexer 9 switches a plurality of the light receiving elements, the outputs of which are added by an output of a receiving light adding amplifier 10, and the elapsed time from the emission of the laser light to receiving the output of the receiving light adding amplifier is measured by a date measuring circuit 11. From the measured time the distance to the body A is calculated by a distance measuring circuit 12. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、走査型レーザレーダに関し、特に、走査レーザと異なる光路で反射光を受光する方式の走査型レーザレーダの監視視野を拡大する技術に関する。
【０００２】
【従来の技術】
レーザ光を走査ミラー（ポリゴンミラーやガルバノミラー等）で走査して前方に放射し、物体からの反射光を受光することにより、物体の有無、物体までの距離、或いは物体の方位等を検出する走査型レーザレーダがある。
【０００３】
かかる走査型レーザレーダとしては、走査レーザ光と同一の光路で反射光を受光する方式（以下、同軸型とする）と走査レーザと異なる光路で反射光を受光する方式（以下、送受分離型とする）がある。
【０００４】
同軸型は、レーザ光源と走査ミラーとの間の光路にハーフミラー或いはビームスプリッタ等を配置し、光源から発射したレーザ光をハーフミラー或いはビームスプリッタを通して走査ミラーに照射し、走査ミラーでレーザ光を走査する。そして、走査レーザ光と同一光路の物体からの反射光を前記走査ミラーで受け、走査ミラーからの反射光を前記ハーフミラー或いはビームスプリッタで反射させ集光レンズで集光して受光素子で受光する構成である（例えば、特許文献１参照）。
【０００５】
送受分離型は、レーザ光源からのレーザ光を走査ミラーに照射し、走査ミラーでレーザ光を走査し、走査レーザ光と異なる光路の物体からの反射光を直接（或いは光学フィルタを介して）集光レンズで集光して受光素子で受光する構成である（例えば、特許文献２参照）。
【０００６】
ところで、走査型レーザレーダを例えば車両等に搭載して前方の障害物の検出や測距等に利用する場合、上述した同軸型では、車両の振動等で走査ミラーが変動して反射光を正確に受光できず、物体の検出精度や測距精度の点で問題がある。このため、走査型レーザレーダを車両等の移動体に搭載する場合には、送受分離型を用いるのが一般的である。
【０００７】
【特許文献１】
特開２０００−２７５３４０号公報
【特許文献２】
特開平１０−３１０６４号公報
【０００８】
【発明が解決しようとする課題】
しかしながら、従来の送受分離型の走査型レーザレーダは、反射光を集光レンズで集光して受光素子に入射する構成である。この場合、受光系の視野角を大きくすると、反射光以外の外光（ノイズ）の受光量が多くなり、Ｓ／Ｎ比（反射光と外光の比）が低下する。このため、従来の送受分離型の走査型レーザレーダを車載装置等に利用する場合には、十分なＳ／Ｎ比を確保するために画角の狭い集光レンズを使用して受光系の視野角を小さく（例えば±５度程度）せざるを得ず、監視視野が狭いという問題がある。
【０００９】
本発明は上記問題点に着目してなされたもので、監視視野を拡大でき広範囲な物体検出領域を有する送受分離型構造の走査型レーザレーダを提供することを目的とする。
【００１０】
【課題を解決するための手段】
このため、請求項１の発明は、レーザ光源からのレーザ光を光走査手段で走査し、走査領域からの反射光を前記走査レーザ光と異なる光路で受光して前記走査領域内を監視する走査型レーザレーダにおいて、多数の受光素子がマトリクス状に配列され前記走査領域からの反射光を結像レンズを介して受光する受光手段と、該受光手段の受光素子の中から指定された複数の受光素子を選択可能な受光素子選択手段と、前記光走査手段の走査位置が変化する毎に当該走査位置に対して予め対応付けられた受光素子及びその周囲の受光素子の選択指令を前記受光素子選択手段に出力し選択する複数の受光素子の切替えを制御する制御手段と、該受光素子選択手段で選択された受光素子の受光出力を加算する受光出力加算手段とを備え、該受光出力加算手段の加算受光出力に基づいて走査領域内を監視する構成とした。
【００１１】
かかる構成では、光走査手段で走査されたレーザ光の反射光を受光する受光手段の受光位置は、レーザ光の走査位置の変化に応じて変化し受光する受光素子位置が変化する。制御手段は、光走査手段の走査位置が変化する毎にその時の走査位置に対して予め対応付けられた受光素子及びその周囲の受光素子の選択指令を受光素子選択手段に出力する。受光素子選択手段は制御手段からの選択指令で選択された複数の受光素子を選択し、受光出力加算手段は受光素子選択手段で選択された受光素子の受光出力を加算し、この加算受光出力に基づいて走査領域内を監視する。このように、レーザ光の走査位置とその走査位置からの反射光が受光される受光素子位置とを予め対応付けておき、レーザ光の走査位置に応じて受光出力を取出す受光素子を限定して順次切替えることにより、受光系の視野角を拡大しても十分なＳ／Ｎ比を確保できるようになる。
【００１２】
請求項２の発明は、前記レーザ光源からレーザ光が発射されてから前記受光出力加算手段の加算受光出力が入力するまでの経過時間を計測する経過時間計測手段と、該経過時間計測手段の計測時間を示す情報に基づいて前記走査領域内の物体までの距離を演算する距離演算手段とを備える構成とした。
【００１３】
かかる構成では、経過時間計測手段はレーザ光が発射されてから加算受光出力が入力するまでの時間を計測し、距離演算手段はその時間を示す情報により物体までの距離を演算する。
【００１４】
請求項３の発明では、前記受光出力加算手段の出力をＡ／Ｄ変換するＡ／Ｄ変換手段と、該Ａ／Ｄ変換手段のディジタル出力に基づいて得られる前記光走査手段の１走査周期当たりの受光波形データを予め定めた走査周期回数加算平均処理する加算平均処理手段とを備え、加算平均処理で得られた受光波形データに基づいて走査領域内を監視する構成とした。
【００１５】
かかる構成では、Ａ／Ｄ変換手段でＡ／Ｄ変換した加算受光出力のディジタル出力に基づいて光走査手段の１走査周期当たりの受光波形データを得る。加算平均処理手段は、１走査周期当たりの受光波形データが得られる毎に加算平均値を演算する。そして、加算平均処理した受光波形データ値に基づいて走査領域内を監視するようにする。
【００１６】
請求項４の発明は、前記光走査手段の各走査位置毎に前記レーザ光源に複数の送光パルスを出力してレーザ光を複数回発射させるレーザ光源駆動手段を設けると共に、前記受光出力加算手段の出力をＡ／Ｄ変換するＡ／Ｄ変換手段と、前記光走査手段の各走査位置毎に前記レーザ光源駆動手段の送光パルスの波形データを一定時間間隔で所定量づつずらして前記Ａ／Ｄ変換手段の受光出力の波形データとの相関値を演算する相関値演算手段とを備え、前記相関値が最大となった時のずれ量に基づいて走査領域内の物体までの距離を演算する構成とした。
【００１７】
かかる構成では、光走査手段の各走査位置でレーザ光源駆動手段から複数の送光パルスをレーザ光源に出力してレーザ光源から複数のレーザ光を発射する。受光出力加算手段の出力をＡ／Ｄ変換手段でＡ／Ｄ変換して受光出力の波形データを得る。そして、送光パルスの波形データを所定量ずつずらして受光出力の波形データとの相関値を演算する。送光パルスの波形データと受光出力の波形データとが一致すると相関値は最大となる。そのときのずれ量が時間に比例し、このずれ量に基づいて走査領域内の物体までの距離を演算する。
【００１８】
請求項５の発明は、前記光走査手段の各走査位置に応じて前記レーザ光源駆動手段の送光パルス数を可変制御し、各走査位置に応じてレーザ光の発射回数を可変制御する構成とした。
【００１９】
具体的には請求項６のように、前記光走査手段を各走査位置で固定してレーザ光を発射し各走査位置において受光出力が検出されるレーザ光発射回数を予め求めて作成した各走査位置と送光パルス数の対応関係を示す発射パルス数テーブルを記憶する発射パルス数テーブル記憶手段を設け、前記光走査手段の走査位置情報が入力した時に前記発射パルス数テーブル記憶手段に記憶された発射パルス数テーブルに基づいて前記レーザ光源駆動手段の送光パルス数を決定する構成とした。
【００２０】
かかる構成では、レーザ光の走査位置に応じてレーザ光の発射回数を可変制御し、レーザ光の照射を必要最小限にする。これにより、例えば室内の監視装置に適用した場合に、人間に対するレーザ光の悪影響を低減できるようになる。
【００２１】
請求項７の発明は、前記光走査手段を各走査位置で固定してレーザ光を発射し各走査位置において前記受光手段の各受光素子の中で受光出力が最大の受光素子位置を予め求めて作成した各走査位置と各受光素子位置の対応関係を示す変換テーブルを記憶する変換テーブル記憶手段を設け、前記制御手段は、前記光走査手段の走査位置情報が入力した時に前記変換テーブル記憶手段に記憶した変換テーブルに基づいて選択する複数の受光素子位置を決定する構成とした。
【００２２】
この場合、請求項８のように、前記変換テーブルを定期的に更新するようにすれば、経年変化等による受光手段における受光位置のずれを補正できる。
請求項９のように、前記光走査手段に、半導体マイクロマシン技術により製造される半導体ミラーを使用すれば、走査型レーザレーダを小型化及び軽量化することができる。
【００２３】
【発明の実施の形態】
以下、本発明の実施形態を図面に基づいて説明する。
図１に、本発明に係る走査型レーザレーダの第１実施形態の構成図を示し、測距装置に適用した場合について説明する。
【００２４】
図１において、本実施形態の走査型レーザレーダ１は、レーザ光を発光するレーザ光源２と、レーザ光源２を駆動するレーザ駆動回路３と、レーザ光を走査する走査ミラー４と、走査ミラー４を駆動制御する走査ミラーコントローラ５と、多数の受光素子がマトリクス状に配列され可視光カット用の光学フィルタ６及び結像レンズ７を介して走査ミラー４によるレーザ光の走査領域内の光学画像が結像される受光手段としての受光素子アレイ８と、受光素子アレイ８の各受光素子の受光出力を選択的に切替え入力する受光素子選択手段としてのマルチプレクサ９と、マルチプレクサ９からの出力を加算する受光出力加算手段としての受光出力加算アンプ１０と、受光出力加算アンプ１０の出力に基づいて測距データを測定するデータ測定回路１１と、前記レーザ駆動回路３、走査ミラーコントローラ５及びマルチプレクサ９の動作を制御すると共にデータ測定回路１１の測定データに基づいて物体までの距離を演算する測距制御回路１２と、マルチプレクサ制御用に走査ミラーコントローラ５の走査位置情報を受光素子位置情報に変換するための変換テーブルを記憶する変換テーブル記憶手段としての変換テーブルメモリ１３とを備えて構成される。図中、Ａは、走査領域内に存在する物体を示す。
【００２５】
前記レーザ駆動回路３は、測距制御回路１２からの動作開始指令で駆動し、レーザ光源２に周期的に送光パルスを出力する。これにより、レーザ光源２は送光パルスの入力毎にレーザ光を走査ミラー４に対して発射する。
【００２６】
前記走査ミラー４としては、例えば本出願人が先に特許第２７２２３１４号等で提案した半導体マイクロマシン技術を応用して製造される半導体ミラーを用いる。この半導体ミラーの構造は特許第２７２２３１４号等で詳述されているので、ここでは図２に従ってその構造を簡単に説明する。
【００２７】
図２は本実施形態で使用する半導体ミラー４の平面図である。走査ミラー４は、互いに直交する一対のトーションバー２１Ａ，２１Ｂと２２Ａ，２２Ｂ及びこれら一対のトーションバー２１Ａ，２１Ｂと２２Ａ，２２Ｂによりそれぞれ軸支される可動板２３，２４が、枠部２５と一体に半導体基板に形成されている。内側可動板２３表面にはミラー２６を有し、内側可動板２３のミラー２６周囲及び外側可動板２４上に、それぞれ駆動コイル２７，２８を有する。また、静磁界を発生する一対の磁石２９Ａ，２９Ｂと３０Ａ，３０Ｂを、例えば枠部２５の外側に対向配置する。尚、図中のＮ，Ｓは、各磁石２９Ａ，２９Ｂと３０Ａ，３０Ｂの磁極を示している。また、各駆動コイル２７，２８は、図示しないがトーションバー部分を介して枠部２５側に引き出されて電極端子（図示せず）に接続し駆動電流が供給されるようになっている。
【００２８】
この走査ミラー４の駆動原理は特許第２７２２３１４号等で詳述されており、ここでは簡単に説明する。
例えば内側可動板２３上の駆動コイル２７に電流を流すと磁界が発生し、この磁界と磁石２９Ａと２９Ｂにより形成せれる静磁界との相互作用によりトーションバー２１Ａ，２１Ｂと平行な可動板２３の対辺部に互いに逆方向の電磁力が作用し、可動板２３がトーションバー２１Ａ，２１Ｂを中心として回動し、回動により発生するトーションバー２１Ａ，２１Ｂのばね力と発生した電磁力とが釣合う位置まで可動板２３は回動する。駆動コイル２７に交流電流を流せば可動板２３は揺動するのでレーザ光を走査できる。そして、発生する電磁力は、駆動コイルに流す電流値に比例するので、駆動コイルの電流値を制御することにより走査ミラー４の揺動角度（レーザ光の走査角度）を制御できる。駆動コイル２８に電流を流せば、同様にして可動板２４がトーションバー２２Ａ，２２Ｂを中心として回動する。従って、両駆動コイル２７，２８への電流供給を制御することにより、走査ミラー４でレーザ光を２次元走査することが可能である。
【００２９】
尚、本発明における走査ミラーとしては、上述の半導体ミラーに限らず従来と同様のポリゴンミラーや機械的なガルバノミラー等を用いてもよい。
前記走査ミラーコントローラ５は、測距制御回路１２からの動作開始指令で駆動し、駆動コイル２７，２８の電流供給を制御して走査ミラー４を揺動駆動すると共に、走査ミラー４に供給する駆動電流値に基づいて走査ミラー４の走査位置情報を測距制御回路１２に送る。ここで、走査ミラー４及び走査ミラーコントローラ５で光走査手段を構成する。
【００３０】
前記マルチプレクサ９は、受光素子アレイ８の受光素子の中から、走査ミラーコントローラ５からの走査位置情報に基づいて測距制御回路１２が指定した複数の受光素子の出力を選択して入力し受光出力加算アンプ１０に出力する。
【００３１】
前記データ測定回路１１は、レーザ駆動回路３から送光パルス発生情報が入力し、図３のように送光パルスの発生から受光出力加算アンプ１０からの加算受光出力が入力するまでの時間Ｔに基づいて物体Ａまでの距離演算に使用するデータを測定する。このデータ測定回路１１の構成例を図４及び図５に示す。
【００３２】
図４は、図３の時間Ｔをカウンタで計数しその計数値を測定データとして出力するカウンタ方式であり、レーザ駆動回路３からの送光パルス発生情報の入力でクロックの計数動作を開始し、受光出力加算アンプ１０からの加算受光出力の入力で計数動作を停止するカウンタ４１を備え、時間Ｔを示すカウンタ４１の計数値を計測時間を示す測定データとして測距制御回路１２に出力する構成である。尚、カウンタ４１は、加算受光出力の入力以前に次の送光パルス発生情報が入力した場合にはカウント値をリセットすると共にカウント動作を開始する。
【００３３】
図５は、図３の時間Ｔを電圧に変換して電圧値を測定データとして出力する時間−電圧変換方式であり、レーザ駆動回路３からの送光パルス発生情報の入力でセットされて出力を発生し、受光出力加算アンプ１０からの加算受光出力の入力でリセットされて出力を停止するフリップフロップ５１と、抵抗を介して入力するフリップフロップ５１の出力を積分する積分器５２とを備え、送光パルスが発生してから加算受光出力が入力するまでの間のフリップフロップ５１の出力を積分器４２で積分することで、時間Ｔを電圧値に変換してこの電圧値を計測時間を示す測定データとして測距制御回路１２に出力する構成である。また、積分器５２は、加算受光出力の入力毎に常開のスイッチ５２ａがＯＮして積分値がリセットされる構成である。尚、積分器５２は、加算受光出力の入力以前に次の送光パルス発生情報が入力した場合も常開のスイッチ５２ａがＯＮして積分値がリセットされる構成になっている。ここで、データ測定回路１１が経過時間計測手段に相当する。
【００３４】
前記測距制御回路１２は、電源投入によりレーザ駆動回路３及び走査ミラーコントローラ５に動作開始指令を出力する。また、測距制御回路１２は、走査ミラーコントローラ５からの走査位置情報の入力により変換テーブルメモリ１３内の変換テーブルを参照し、入力した走査位置情報に対応する受光素子位置及び予め定めたその周囲の受光素子位置を決定しその選択指令をマルチプレクサ９に出力して受光出力加算アンプ１０で加算する受光出力を選択制御する。また、レーザ駆動回路３からの送光パルス発生情報の入力毎に、データ測定回路１１の出力状態を監視し、次の送光パルス発生情報入力以前にデータ測定回路１１の出力値がリセットされた場合は、受光出力によるリセットと判断してデータ測定回路１１のデータ値に基づいて測距動作を実行し、次の送光パルス発生情報入力と同時にデータ測定回路１１の出力値がリセットされた場合は、送光パルスによるリセットと判断してデータ測定回路１１のデータ値を無効として測距動作を行わない構成である。従って、測距制御回路１２が制御手段及び距離演算手段の機能を備える。
【００３５】
次に、第１実施形態の走査型レーザレーダ１の動作を説明する。
電源を投入すると測距制御回路１２からレーザ駆動回路３及び走査ミラーコントローラ５に動作開始指令が出力され、レーザ駆動回路３から周期的に送光パルスが発生し、レーザ光源２からレーザ光が間欠的に走査ミラー４に照射される。また、走査ミラーコントローラ５により走査ミラー４を駆動し、例えば走査角±３０°の範囲でレーザ光を２次元走査する。レーザ光の走査範囲内に物体Ａが存在すれば、レーザ光は物体Ａで反射され、その散乱光は光学フィルタ６で可視光がカットされ結像レンズ７を介して受光素子アレイ８に入射し、物体Ａの光学画像が受光素子アレイ８上に結像される。
【００３６】
受光素子アレイ８は、受光領域が走査ミラー４の走査領域と対応するよう形成されており、受光領域に図６のように所定数の受光素子８ａがマトリクス状に配列されている。尚、受光素子としては、通常アバランシェフォトダイオードを用いるがＰＩＮフォトダイオードを用いてもよい。そして、走査ミラー４でレーザ光を２次元走査した時の図７に示す走査面の各レーザスポット位置（図中斜線で示す）と、このレーザスポット位置からの反射光を受光する受光素子アレイ８の各受光素子位置とを予め対応させている。この対応関係は変換テーブルとして変換テーブルメモリ１３に記憶されている。
【００３７】
変換テーブルは、図７の走査面における全てのレーザスポット位置毎に、走査ミラー４の走査位置（レーザスポット位置）を固定し、その走査位置で出力が最大となる受光素子位置を調べることにより作成する。この操作により得られたレーザスポット位置と受光素子位置の対応関係を変換テーブルとして変換テーブルメモリ１３に記憶させる。
【００３８】
今、走査ミラー４により走査されたレーザ光が図７の走査面内の走査位置Ｓｘｙにある時、この走査位置Ｓｘｙでの反射光が受光される受光素子アレイ８上の受光素子位置が図６のＤｘｙとする。この場合、走査ミラーコントローラ５から走査位置Ｓｘｙを示す走査位置情報が測距制御回路１２に入力すると、測距制御回路１２は、変換テーブルメモリ１３内の変換テーブルにより走査位置Ｓｘｙに対応する受光素子アレイ８上の受光素子位置Ｄｘｙを得る。そして、この受光素子位置Ｄｘｙとその周囲の受光素子位置Ｄ（ｘ＋１）ｙ、Ｄ（ｘ−１）ｙ、Ｄｘ（ｙ＋１）、Ｄｘ（ｙ−１）の選択指令をマルチプレクサ９に出力し、マルチプレクサ９は前記各位置Ｄｘｙ、Ｄ（ｘ＋１）ｙ、Ｄ（ｘ−１）ｙ、Ｄｘ（ｙ＋１）、Ｄｘ（ｙ−１）の受光素子の出力を選択して入力し、受光出力加算アンプ１０に出力する。
【００３９】
ここで、位置Ｄｘｙだけでなくその周囲の位置Ｄ（ｘ＋１）ｙ、Ｄ（ｘ−１）ｙ、Ｄｘ（ｙ＋１）、Ｄｘ（ｙ−１）も選択して加算する理由は、レーザスポットが走査位置Ｓｘｙとその周囲の走査位置Ｓ（ｘ＋１）ｙ、Ｓ（ｘ−１）ｙ、Ｓｘ（ｙ＋１）、Ｓｘ（ｙ−１）の境界近傍を含む場合、位置Ｄｘｙの周囲の位置Ｄ（ｘ＋１）ｙ、Ｄ（ｘ−１）ｙ、Ｄｘ（ｙ＋１）、Ｄｘ（ｙ−１）の受光素子の出力を加算することにより、十分な受光レベルを確保するためである。これにより、走査ミラー４に半導体ミラーのようなミラー面積の小さいものを使用しても受光信号を検出するのに十分は受光レベルを確保できる。
【００４０】
受光出力加算アンプ１０は、入力する受光出力を加算し、その加算受光出力をデータ測定回路１１に入力する。データ測定回路１１は、図４の構成であればカウンタ４１の計数値を測定データとして測距制御回路１２に出力し、図５の構成であれば積分器５２の電圧データを測定データとして測距制御回路１２に出力する。この走査位置において反射光が受光されれば、データ測定回路１１のデータ値は次の送光パルス発生情報の入力以前に受光出力でリセットされる。測距制御回路１２は、次の送光パルス発生情報の入力以前にデータ測定回路１１のデータ値がリセットされたか否かに基づいて物体Ａからの反射光の有無を判断し、次の送光パルス発生情報の入力以前にデータ値がリセットされた時には、データ測定回路１１の測定データに基づいて物体Ａまでの距離を演算する。
【００４１】
かかる構成によれば、画角の広い結像レンズを使用して受光系の視野角を拡大した場合でも、走査領域内の極めて狭いレーザスポット範囲からの入射光に限定して受光の有無を監視するので、従来の同軸型と同等以上のＳ／Ｎ比を得ることができ、十分な物体検出精度を確保できる。また、物体の監視視野を大幅に拡大できる。更に、変換テーブルを使用することにより、結像レンズ７の収差による誤差、レーザ光の送光と受光の光軸の不一致による誤差、走査ミラーに対するレーザ光の入射角による光学歪による誤差等を補正して、正確な受光位置を得ることができ、物体検出や測距の精度が向上する。更には、走査ミラー４として半導体ミラーを使用すれば、レーザレーダの小型化及び軽量化を図ることができるので、移動体に搭載する車載装置に利用する場合に有効である。変換テーブルの更新を定期的に実施すれば、経時変化等による受光位置のずれ等を較正でき、物体検出や測距の精度を維持することができる。
【００４２】
尚、走査ミラー４の走査は、２次元に限らず１次元でもよいことは言うまでもない。
次に、本発明の第２実施形態を説明する。
【００４３】
図８に、第２実施形態の構成図を示す。尚、第１実施形態と同一要素には同一符号を付す。
図８において、第２実施形態の走査型レーザレーダ１は、第１実施形態の構成に加えて、Ａ／Ｄ変換器１４と、サンプリングクロック発生器１５と、波形データメモリ１６とを備える。
【００４４】
Ａ／Ｄ変換器１４は、サンプリングクロック発生器１５のサンプリングクロックの入力毎に受光出力加算アンプ１０の出力値をサンプリングして、受光出力加算アンプ１０からのアナログ信号をディジタル信号に変換して測距制御回路１２に送る。ここで、Ａ／Ｄ変換器１４及びサンプリングクロック発生器１５でＡ／Ｄ変換手段を構成する。
【００４５】
測距制御回路１２は、走査ミラーコントローラ５からの走査位置情報に基づいてＡ／Ｄ変換器１４から入力するディジタル信号から走査ミラー４の１走査周期における受光出力の波形データを作成して波形データメモリ１６に記憶する。また、測距制御回路１２は、次の波形データが入力する毎に、波形データメモリ１６に記憶されている波形データと加算平均し、波形データメモリ１６内の波形データを加算平均処理した新たな波形データに書き換えて更新する。ここで、本実施形態の測距制御回路１２は加算平均処理手段の機能を備える。
【００４６】
尚、第２実施形態の測距制御回路１２は、第１実施形態のデータ測定回路１１の機能を備える。測距制御回路１２は、レーザ駆動回路３からの送光パルス発生情報と波形データメモリ１６に記憶した波形データ情報に基づいて送光パルスの発生から受光出力が発生するまでの時間を計測し、計測値に基づいて物体Ａまでの距離を演算する。
【００４７】
次に、第２実施形態の動作を説明する。
走査ミラー４によりレーザ光を走査し、受光素子アレイ８の受光出力を受光出力加算アンプ１０で加算するまでは第１実施形態と同様の動作である。第２実施形態では、受光出力加算アンプ１０からの出力信号をＡ／Ｄ変換器１４でディジタル信号に変換し測距制御回路１２に入力する。測距制御回路１２は、走査ミラーコントローラ５からの走査位置情報に基づいて走査ミラー４の１走査周期の波形データを得て、新たな波形データを得る毎に波形データメモリ１６に記憶した波形データと加算平均して波形データメモリ１６の波形データを更新する。
【００４８】
例えば、サンプリングクロック周波数を１ＧＨｚとした場合、走査ミラー４の１走査周期では、図９（Ａ）のような１ｎｓｅｃ毎のサンプリングデータによる受信波形データが得られる。この受信波形データを加算平均処理することにより、波形データに含まれるノイズ成分が低減されレーザ光の反射光成分が大きくなり、図９の（Ｂ）のような受光出力の明確な受信波形データが得られる。
【００４９】
測距制御回路１２は、予め設定した所定回数の加算平均処理した波形データを用い、その波形データに受光出力が存在する場合には、受光出力が得られた走査ミラー４の走査位置に対する送光パルス発生情報と波形データの受光出力情報とに基づいて時間Ｔを演算し、物体Ａまでの距離を演算する。
【００５０】
かかる第２実施形態の構成によれば、移動体以外の例えば道路面や室内等の物体監視に使用する走査速度が低速で十分なレーザレーダとして本発明の走査型レーザレーダを利用する場合に、走査速度が高速（１ｋＨｚ以上が一般的である）である図２のような半導体ミラーを走査ミラー４として使用しても、十分なＳ／Ｎ比が得られ、高精度且つ広範囲な物体監視ができる。そして、半導体ミラーを使用することにより、この種の低速走査用レーザレーダの小型・軽量化を図ることができる。
【００５１】
次に、本発明の第３実施形態を説明する。
図１０に、第３実施形態の構成図を示す。尚、第２実施形態と同一要素には同一符号を付す。
【００５２】
図１０において、第３実施形態の走査型レーザレーダ１は、第２実施形態の波形データメモリ１６を除いて、複数パルス発生回路１７、Ａ／Ｄ変換値メモリ１８及び発射パルス数テーブル記憶手段としての発射パルス数テーブルメモリ１９を加えた構成である。
【００５３】
複数パルス発生回路１７は、例えば図１１に示すように、複数のスイッチ素子（例えばパワーＭＯＳＦＥＴ等）１７−１〜１７−ｉ、コンデンサＣ１〜Ｃｉ等を備え、走査ミラー４の各走査位置毎に図１２に示すようにレーザ駆動回路３から例えば一定間隔で順次出力される複数のトリガパルスＴｐ１〜Ｔｐｉによりスイッチ素子１７−１〜１７−ｉが順次ＯＮすることにより、送信区間において複数の送光パルスＩｐを発生してレーザ光源２に出力する構成である。ここで、複数パルス発生回路１７及びレーザ駆動回路３でレーザ光源駆動手段を構成する。
【００５４】
Ａ／Ｄ変換値メモリ１８は、Ａ／Ｄ変換器１４からの受光出力のディジタル値を記憶し、走査ミラー４の各走査位置毎の受光出力状態を記憶する。
本実施形態の測距制御回路１２は、走査ミラーコントローラ５からの走査位置情報に基づいて走査位置が変わる毎にＡ／Ｄ変換値メモリ１８に記憶された受光波形を取込み、レーザ駆動回路３からのトリガパルス発生情報から得られるレーザ光の送光波形と取込んだ受光波形との相関値を演算し、相関値が予め設定した閾値以上のときに受光出力ありと判断し、相関値が最大となるずれ量に基づいて物体まで距離を演算する。ここで、本実施形態の測距制御回路１２は相関値演算手段の機能を備える。
【００５５】
発射パルス数テーブルメモリ１９は、走査ミラー４の走査方向と発射パルス数の対応関係を記憶するものである。この発射パルス数テーブルは、走査ミラー４の走査位置（前述のレーザスポット位置）を固定し、発射パルス数を可変して受光出力が得られる発射パルス数を調べる。この操作を図７の走査面における全てのレーザスポット位置について行い作成する。反射率の高い物体に対しては少ない発射パルス数が設定され、反射率の低い物体に対しては多い発射パルス数が設定される。
【００５６】
尚、この発射パルス数テーブルは、本発明の走査型レーザレーダを、監視領域の環境がほとんど変化しない屋内等の監視装置に利用する場合に使用するものであり、車載装置等のような屋外で使用する場合には不用である。車載装置等のような屋外で使用する場合には、走査ミラー４の走査方向に関係なく受光出力が十分得られる予め設定した一定数の複数の送光パルスを発射するような構成とする。
【００５７】
次に、本発明の第３実施形態を車載装置に適用する場合について説明する。
電源を投入すると測距制御回路１２からレーザ駆動回路３及び走査ミラーコントローラ５に動作開始指令が出力され、走査ミラー４の各走査位置でレーザ駆動回路３から予め設定された複数のトリガパルスが発生し、複数パルス発生回路１７からの複数の送光パルスＩｐに入力によりレーザ光源２から複数のレーザ光が走査ミラー４に照射される。従って、走査ミラー４の各走査位置に対して複数のレーザ光が照射される。また、レーザ駆動回路３からはトリガパルス発生情報が測距制御回路１２に入力する。
【００５８】
一方、受光系では第１及び第２実施形態と同様にして走査ミラー４の走査位置情報に基づいてマルチプレクサ９により受光素子アレイ８の出力が選択され、選択された受光出力を受光出力加算アンプ１０で加算し、加算受光出力をＡ／Ｄ変換器１４でディジタル信号に変換してＡ／Ｄ変換値メモリ１８に記憶する。測距制御回路１２は、走査ミラー４の走査位置が変わる毎にＡ／Ｄ変換値メモリ１８内の受光波形を取込み、その走査位置に対するレーザ光の送光波形と取込んだ受光波形の相関値を演算する。具体的には、送光波形を１サンプリングクロック毎に所定量Δｔずらしながら受光波形との相関値を求める。受光出力が存在すれば図１３に示すように送光波形と受光波形とが一致した時に相関値は最大となり、その時のずれ量は送光パルスの発生から受光出力が得られるまでの時間Ｔに比例するので、このずれ量から時間Ｔを求め、物体Ａまでの距離を演算する。受光出力がなければ送光波形と受光波形との相関値は閾値以上になることはなく、受光出力なしと判断して距離の演算は行わない。
【００５９】
かかる第３実施形態のように、走査ミラー４の各走査位置に対して複数回レーザ光を照射し、その時の送光波形と受光波形の相関値に基づいて受光出力の有無を判定する構成とすれば、レーザ光を１回だけ照射する場合に比較してレーザ光をｎ回照射すれば（ｎ−（ｎ）^１／２）倍にＳ／Ｎ比が向上し、物体の検出精度及び測距精度を向上できる。レーザ光をｎ回照射した場合、信号成分は照射パルス数に比例するがノイズ成分は相互に打ち消し（ｎ）^１／２倍にしかならないためである。
【００６０】
監視領域の環境がほとんど変化しない屋内等の監視装置に利用する場合には、走査ミラー４の走査位置情報に基づいて発射パルス数テーブルメモリ１９に記憶された発射パルス数テーブルからその走査位置での発射パルス数を決定し、各走査位置毎に設定された必要最小限の数のレーザ光を発射するようにする。これにより、レーザ光の人間に対する悪影響を低減でき安全性を向上できる。
【００６１】
尚、第３実施形態では、複数パルス発生回路１７内のスイッチ素子１７−１〜１７−ｉを全てＯＮさせて複数の送光パルスを生成する構成としたが、一部をＯＮさせないようにすることにより、送光パルス列に例えば「１００１１・・・」のようにコード変調をかけて送信するようにしてもよい。
【００６２】
【発明の効果】
以上説明したように本発明によれば、多数の受光素子からなる受光手段に結像レンズを用いてレーザ光の走査領域の光学画像を結像させると共に、レーザ光の走査位置に合わせて受光素子を限定してその反射光による受光出力を取出す構成としたので、受光系の視野を広げても十分なＳ／Ｎ比を確保でき、走査型レーザレーダの監視領域を拡大できる。
【００６３】
また、受光出力をディジタル加算平均処理したり、或いは、走査位置毎に複数のレーザ光を発射しその時の送信パルス波形と受光出力波形の相関値を求めたりして、受光出力を得る構成とすることで、速い走査速度の必要がない低速走査型の監視装置に適用した場合に、光走査手段に走査速度の速い半導体ミラーを使用しても十分なＳ／Ｎ比が得られるようになる。
【００６４】
また、走査位置に応じてレーザ光の発射数を可変制御し、レーザ光の発射数を必要最小限とすることで、人間に対するレーザ光の悪影響を低減でき、安全性を向上できる。
【００６５】
また、光走査手段に極めて小型、軽量の半導体ミラーを使用すれば、走査型レーザレーダを格段に小型化及び軽量化できる。
【図面の簡単な説明】
【図１】本発明に係る走査型レーザレーダの第１実施形態の構成図
【図２】同上実施形態の走査ミラーに用いる半導体ミラーの平面図
【図３】送光パルスと受信信号の関係を示す図
【図４】データ測定回路の一例を示す構成図
【図５】データ測定回路の別の例を示す構成図
【図６】受光素子アレイを示す図
【図７】レーザ光の走査面とレーザスポットの関係を示す図
【図８】本発明に係る走査型レーザレーダの第２実施形態の構成図
【図９】（Ａ）は１走査周期の受信波形図、（Ｂ）は加算平均処理後の受信波形図
【図１０】本発明に係る走査型レーザレーダの第３実施形態の構成図
【図１１】複数パルス発生回路の要部回路図
【図１２】トリガパルスと送光パルスの関係を示す図
【図１３】送光波形、受光波形及び相関値の関係を示す図
【符号の説明】
１走査型レーザレーダ
２レーザ光源
３レーザ駆動回路
４走査ミラー
５走査ミラーコントローラ
６光学フィルタ
７結像レンズ
８受光素子アレイ
９マルチプレクサ
１０受光出力加算アンプ
１１データ測定回路
１２測距制御回路
１３変換テーブルメモリ
１４Ａ／Ｄ変換器
１５サンプリングクロック発生器
１６波形データメモリ
１７複数パルス発生回路
１８Ａ／Ｄ変換値メモリ
１９発射パルス数テーブルメモリ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a scanning laser radar, and more particularly, to a technique for enlarging a monitoring field of view of a scanning laser radar that receives reflected light in an optical path different from that of a scanning laser.
[0002]
[Prior art]
Laser light is scanned by a scanning mirror (polygon mirror, galvano mirror, etc.) and emitted forward, and the presence or absence of an object, the distance to the object, or the azimuth of the object is detected by receiving reflected light from the object. There is a scanning laser radar.
[0003]
Such a scanning laser radar includes a method of receiving reflected light in the same optical path as the scanning laser light (hereinafter referred to as a coaxial type) and a method of receiving reflected light in an optical path different from the scanning laser (hereinafter referred to as a transmission / reception separating type). Do).
[0004]
In the coaxial type, a half mirror or a beam splitter is disposed in an optical path between a laser light source and a scanning mirror, and the laser light emitted from the light source is irradiated on the scanning mirror through the half mirror or the beam splitter, and the scanning mirror emits the laser light. Scan. Then, the reflected light from the object on the same optical path as the scanning laser light is received by the scanning mirror, the reflected light from the scanning mirror is reflected by the half mirror or the beam splitter, condensed by a condenser lens, and received by a light receiving element. (See, for example, Patent Document 1).
[0005]
The transmission / reception separation type irradiates a scanning mirror with laser light from a laser light source, scans the laser light with the scanning mirror, and collects reflected light from an object on an optical path different from the scanning laser light directly (or via an optical filter). In this configuration, light is condensed by an optical lens and received by a light receiving element (for example, see Patent Document 2).
[0006]
By the way, when the scanning laser radar is mounted on a vehicle or the like and is used for detecting an obstacle ahead or measuring a distance, for example, in the above-described coaxial type, the scanning mirror fluctuates due to vibration of the vehicle and the reflected light is accurately reflected. And there is a problem in terms of object detection accuracy and distance measurement accuracy. For this reason, when the scanning laser radar is mounted on a moving body such as a vehicle, it is general to use a transmission / reception separation type.
[0007]
[Patent Document 1]
JP 2000-275340 A
[Patent Document 2]
JP-A-10-31064
[0008]
[Problems to be solved by the invention]
However, the conventional transmission / reception-type scanning laser radar has a configuration in which reflected light is condensed by a condenser lens and incident on a light receiving element. In this case, when the viewing angle of the light receiving system is increased, the amount of external light (noise) received other than the reflected light is increased, and the S / N ratio (the ratio between the reflected light and the external light) is reduced. For this reason, when a conventional transmission / reception separation type scanning laser radar is used for an in-vehicle device or the like, in order to ensure a sufficient S / N ratio, a light-gathering lens having a narrow angle of view is used and the field of view of the light-receiving system is used. There is a problem that the angle has to be small (for example, about ± 5 degrees) and the monitoring field of view is narrow.
[0009]
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a scanning type laser radar having a transmission / reception-separated type structure having a wide monitoring object field and a wide object detection area.
[0010]
[Means for Solving the Problems]
For this reason, the invention according to claim 1 is a scanning method in which laser light from a laser light source is scanned by an optical scanning unit, and reflected light from a scanning area is received on an optical path different from that of the scanning laser light to monitor the inside of the scanning area. In a type laser radar, a plurality of light receiving elements are arranged in a matrix and receive light reflected from the scanning area via an imaging lens, and a plurality of light receiving elements designated from among the light receiving elements of the light receiving means A light-receiving element selecting means capable of selecting an element, and each time the scanning position of the optical scanning means changes, a light-receiving element previously associated with the scanning position and a selection command of light-receiving elements around the scanning position are transmitted to the light-receiving element selection Control means for controlling the switching of the plurality of light receiving elements to be output to the light receiving means, and light receiving output adding means for adding the light receiving outputs of the light receiving elements selected by the light receiving element selecting means; And configured to monitor the scanning area based on the addition light output means.
[0011]
In such a configuration, the light receiving position of the light receiving unit that receives the reflected light of the laser light scanned by the optical scanning unit changes according to the change in the scanning position of the laser light, and the light receiving element position that receives the light changes. Each time the scanning position of the optical scanning means changes, the control means outputs to the light receiving element selecting means a selection command for the light receiving element and the surrounding light receiving element which are previously associated with the scanning position at that time. The light receiving element selecting means selects a plurality of light receiving elements selected by the selection command from the control means, and the light receiving output adding means adds the light receiving outputs of the light receiving elements selected by the light receiving element selecting means, and The inside of the scanning area is monitored on the basis of this. In this way, the scanning position of the laser light and the light receiving element position at which the reflected light from the scanning position is received are previously associated with each other, and the light receiving element that takes out the light receiving output according to the scanning position of the laser light is limited. By switching sequentially, a sufficient S / N ratio can be secured even when the viewing angle of the light receiving system is increased.
[0012]
The invention according to claim 2 is an elapsed time measuring means for measuring an elapsed time from when the laser light is emitted from the laser light source to when the added light receiving output of the light receiving output adding means is inputted, and a measurement of the elapsed time measuring means. A distance calculating unit configured to calculate a distance to an object in the scanning area based on information indicating time.
[0013]
In such a configuration, the elapsed time measuring means measures the time from when the laser light is emitted to when the added light receiving output is input, and the distance calculating means calculates the distance to the object based on the information indicating the time.
[0014]
According to a third aspect of the present invention, there is provided an A / D conversion means for A / D converting an output of the light reception output addition means, and a scanning cycle of the optical scanning means obtained based on a digital output of the A / D conversion means. Averaging processing means for averaging the received light waveform data for a predetermined number of scanning periods, and monitoring the inside of the scanning area based on the received light waveform data obtained by the averaging processing.
[0015]
With such a configuration, light-receiving waveform data per scanning cycle of the optical scanning means is obtained based on the digital output of the added light-receiving output A / D-converted by the A / D conversion means. The averaging processing means calculates an averaging value each time light reception waveform data per scanning cycle is obtained. Then, the inside of the scanning area is monitored based on the light receiving waveform data value subjected to the averaging process.
[0016]
The invention according to claim 4, wherein a laser light source driving means for outputting a plurality of light transmission pulses to the laser light source at each scanning position of the light scanning means to emit laser light a plurality of times is provided, and the light receiving output adding means is provided. A / D conversion means for A / D converting the output of the optical scanning means; and the A / D conversion means for shifting the waveform data of the light transmission pulse of the laser light source driving means by a predetermined amount at predetermined time intervals for each scanning position of the optical scanning means. Correlation value calculation means for calculating a correlation value with the waveform data of the light reception output of the D conversion means, and calculates a distance to an object in the scanning area based on a shift amount when the correlation value becomes maximum. Configuration.
[0017]
In such a configuration, a plurality of light transmission pulses are output from the laser light source driving unit to the laser light source at each scanning position of the optical scanning unit, and the laser light source emits a plurality of laser beams. The output of the light receiving output adding means is A / D converted by the A / D converting means to obtain waveform data of the light receiving output. Then, the correlation value with the waveform data of the light receiving output is calculated by shifting the waveform data of the light transmission pulse by a predetermined amount. When the waveform data of the light transmission pulse matches the waveform data of the light reception output, the correlation value becomes maximum. The shift amount at that time is proportional to time, and the distance to the object in the scanning area is calculated based on the shift amount.
[0018]
The invention according to claim 5, wherein the number of light transmission pulses of the laser light source driving means is variably controlled in accordance with each scanning position of the optical scanning means, and the number of laser light emission times is variably controlled in accordance with each scanning position. did.
[0019]
Specifically, each of the scans prepared by previously obtaining the number of laser light emission times at which the optical scanning means is fixed at each scanning position to emit laser light and the light receiving output is detected at each scanning position, as in claim 6 A firing pulse number table storing means for storing a firing pulse number table indicating a correspondence relationship between a position and a light transmitting pulse number is provided, and when the scanning position information of the optical scanning means is input, the firing pulse number table storing means is stored. The number of light transmission pulses of the laser light source driving means is determined based on the number of emission pulse tables.
[0020]
In such a configuration, the number of times laser light is emitted is variably controlled in accordance with the scanning position of the laser light to minimize laser light irradiation. This makes it possible to reduce the adverse effect of laser light on humans when applied to, for example, an indoor monitoring device.
[0021]
According to a seventh aspect of the present invention, the light scanning means is fixed at each scanning position, and a laser beam is emitted. At each scanning position, a light receiving element position having the maximum light receiving output among the light receiving elements of the light receiving means is obtained in advance. Conversion table storage means for storing a conversion table indicating the correspondence between each created scanning position and each light receiving element position is provided, and the control means stores the conversion table in the conversion table storage means when scanning position information of the optical scanning means is input. The configuration is such that a plurality of light receiving element positions to be selected are determined based on the stored conversion table.
[0022]
In this case, if the conversion table is periodically updated as in claim 8, it is possible to correct a shift in the light receiving position of the light receiving unit due to aging or the like.
If a semiconductor mirror manufactured by a semiconductor micromachine technology is used for the optical scanning means, the size and weight of the scanning laser radar can be reduced.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a configuration diagram of a first embodiment of a scanning laser radar according to the present invention, and a case where the scanning laser radar is applied to a distance measuring device will be described.
[0024]
In FIG. 1, a scanning laser radar 1 according to the present embodiment includes a laser light source 2 that emits laser light, a laser driving circuit 3 that drives the laser light source 2, a scanning mirror 4 that scans the laser light, and a scanning mirror 4 A scanning mirror controller 5 for driving and controlling, a large number of light receiving elements arranged in a matrix, an optical filter 6 for cutting visible light, and an optical image in a scanning region of the laser beam by the scanning mirror 4 via an imaging lens 7. A light receiving element array 8 as light receiving means to be imaged, a multiplexer 9 as light receiving element selecting means for selectively switching and inputting a light receiving output of each light receiving element of the light receiving element array 8, and an output from the multiplexer 9 are added. Light receiving output adding amplifier 10 as light receiving output adding means, and a data measuring circuit for measuring distance measurement data based on the output of light receiving output adding amplifier 10 1, a distance measurement control circuit 12 for controlling operations of the laser drive circuit 3, the scanning mirror controller 5, and the multiplexer 9, and calculating a distance to an object based on measurement data of the data measurement circuit 11, and a multiplexer control. It is provided with a conversion table memory 13 as a conversion table storing means for storing a conversion table for converting the scanning position information of the scanning mirror controller 5 into the light receiving element position information. In the figure, A indicates an object existing in the scanning area.
[0025]
The laser drive circuit 3 is driven by an operation start command from the distance measurement control circuit 12 and periodically outputs a light transmission pulse to the laser light source 2. Thus, the laser light source 2 emits laser light to the scanning mirror 4 every time a light transmission pulse is input.
[0026]
As the scanning mirror 4, for example, a semiconductor mirror manufactured by applying the semiconductor micromachine technology proposed by the present applicant in Japanese Patent No. 2722314 or the like is used. Since the structure of this semiconductor mirror is described in detail in Japanese Patent No. 2722314, the structure will be briefly described with reference to FIG.
[0027]
FIG. 2 is a plan view of the semiconductor mirror 4 used in the present embodiment. The scanning mirror 4 includes a pair of torsion bars 21A, 21B and 22A, 22B which are orthogonal to each other, and movable plates 23, 24 which are respectively supported by the pair of torsion bars 21A, 21B, 22A, 22B. Formed on a semiconductor substrate. A mirror 26 is provided on the surface of the inner movable plate 23, and drive coils 27 and 28 are provided around the mirror 26 of the inner movable plate 23 and on the outer movable plate 24, respectively. In addition, a pair of magnets 29A, 29B and 30A, 30B that generate a static magnetic field are arranged, for example, opposite to the outside of the frame 25. Incidentally, N and S in the figure indicate the magnetic poles of the magnets 29A and 29B and 30A and 30B. Although not shown, each of the drive coils 27 and 28 is drawn out toward the frame 25 through a torsion bar portion, and is connected to an electrode terminal (not shown) so that a drive current is supplied.
[0028]
The driving principle of this scanning mirror 4 is described in detail in Japanese Patent No. 2722314 and the like, and will be briefly described here.
For example, when a current is applied to the drive coil 27 on the inner movable plate 23, a magnetic field is generated, and the interaction between the magnetic field and the static magnetic field formed by the magnets 29A and 29B causes the movable plate 23 parallel to the torsion bars 21A and 21B to move. Electromagnetic forces in opposite directions act on opposite sides, and the movable plate 23 rotates about the torsion bars 21A, 21B. The spring force of the torsion bars 21A, 21B generated by the rotation and the generated electromagnetic force are fished. The movable plate 23 rotates to a position where it fits. When an alternating current is applied to the drive coil 27, the movable plate 23 swings, so that the laser beam can be scanned. Since the generated electromagnetic force is proportional to the current value flowing through the drive coil, the swing angle (scanning angle of the laser beam) of the scanning mirror 4 can be controlled by controlling the current value of the drive coil. When a current is applied to the drive coil 28, the movable plate 24 is similarly rotated about the torsion bars 22A and 22B. Therefore, by controlling the current supply to both drive coils 27 and 28, the scanning mirror 4 can perform two-dimensional scanning of the laser beam.
[0029]
The scanning mirror in the present invention is not limited to the above-described semiconductor mirror, but may be a polygon mirror or a mechanical galvano mirror similar to the conventional one.
The scanning mirror controller 5 is driven by an operation start command from the distance measurement control circuit 12, controls the current supply to the drive coils 27 and 28, drives the scanning mirror 4 to swing, and supplies the scanning mirror 4 with the driving mirror. The scanning position information of the scanning mirror 4 is sent to the distance measurement control circuit 12 based on the current value. Here, the scanning mirror 4 and the scanning mirror controller 5 constitute an optical scanning unit.
[0030]
The multiplexer 9 selects and inputs, from among the light receiving elements of the light receiving element array 8, outputs of a plurality of light receiving elements designated by the distance measurement control circuit 12 based on scanning position information from the scanning mirror controller 5, and outputs the received light. Output to the addition amplifier 10.
[0031]
The data measurement circuit 11 receives the light transmission pulse generation information from the laser driving circuit 3 and outputs the light transmission pulse generation time T from the generation of the light transmission pulse to the input of the added light reception output from the light reception output addition amplifier 10 as shown in FIG. Based on this, data used for calculating the distance to the object A is measured. 4 and 5 show examples of the configuration of the data measurement circuit 11. FIG.
[0032]
FIG. 4 shows a counter system in which the time T in FIG. 3 is counted by a counter and the count value is output as measurement data. The clock counting operation is started by input of light transmission pulse generation information from the laser drive circuit 3, A counter 41 for stopping the counting operation in response to the input of the added light receiving output from the light receiving output adding amplifier 10 is provided, and the count value of the counter 41 indicating the time T is output to the distance measurement control circuit 12 as measurement data indicating the measurement time. is there. The counter 41 resets the count value and starts the counting operation when the next light transmission pulse generation information is input before the input of the added light receiving output.
[0033]
FIG. 5 shows a time-voltage conversion method in which the time T in FIG. 3 is converted into a voltage and a voltage value is output as measurement data. A flip-flop 51 which generates and is reset by the input of the added light-receiving output from the light-receiving output adding amplifier 10 to stop the output, and an integrator 52 which integrates the output of the flip-flop 51 input via a resistor. By integrating the output of the flip-flop 51 from the generation of the light pulse to the input of the added light receiving output by the integrator 42, the time T is converted into a voltage value, and this voltage value is measured to indicate the measurement time. In this configuration, data is output to the distance measurement control circuit 12 as data. Further, the integrator 52 is configured such that the normally open switch 52a is turned on and the integrated value is reset every time the added light receiving output is input. The integrator 52 is configured such that the normally open switch 52a is turned on to reset the integrated value even when the next light transmission pulse generation information is input before the input of the added light receiving output. Here, the data measurement circuit 11 corresponds to an elapsed time measurement unit.
[0034]
The ranging control circuit 12 outputs an operation start command to the laser drive circuit 3 and the scanning mirror controller 5 when the power is turned on. In addition, the distance measurement control circuit 12 refers to the conversion table in the conversion table memory 13 by inputting the scanning position information from the scanning mirror controller 5, and detects the light receiving element position corresponding to the input scanning position information and a predetermined surrounding area. And outputs the selection command to the multiplexer 9 to select and control the light receiving output to be added by the light receiving output adding amplifier 10. Further, each time light transmission pulse generation information is input from the laser drive circuit 3, the output state of the data measurement circuit 11 is monitored, and the output value of the data measurement circuit 11 is reset before the next light transmission pulse generation information is input. In this case, when the reset is determined by the light receiving output, the distance measuring operation is performed based on the data value of the data measuring circuit 11, and the output value of the data measuring circuit 11 is reset simultaneously with the input of the next light transmission pulse generation information. Is a configuration in which a reset is made by a light transmission pulse, the data value of the data measurement circuit 11 is invalidated, and the distance measurement operation is not performed. Therefore, the distance measurement control circuit 12 has functions of a control unit and a distance calculation unit.
[0035]
Next, the operation of the scanning laser radar 1 according to the first embodiment will be described.
When the power is turned on, an operation start command is output from the distance measurement control circuit 12 to the laser driving circuit 3 and the scanning mirror controller 5, and the laser driving circuit 3 periodically generates a light transmission pulse, and the laser light from the laser light source 2 is intermittent. Irradiated on the scanning mirror 4. Further, the scanning mirror 4 is driven by the scanning mirror controller 5, and the laser beam is two-dimensionally scanned within a range of, for example, a scanning angle of ± 30 °. If the object A exists within the scanning range of the laser light, the laser light is reflected by the object A, and the scattered light is cut into visible light by the optical filter 6 and enters the light receiving element array 8 via the imaging lens 7. The optical image of the object A is formed on the light receiving element array 8.
[0036]
The light receiving element array 8 is formed so that the light receiving area corresponds to the scanning area of the scanning mirror 4, and a predetermined number of light receiving elements 8a are arranged in a matrix in the light receiving area as shown in FIG. Note that an avalanche photodiode is usually used as the light receiving element, but a PIN photodiode may be used. Then, when the laser beam is two-dimensionally scanned by the scanning mirror 4, each laser spot position (shown by oblique lines) on the scanning surface shown in FIG. 7 and a light receiving element array 8 which receives reflected light from this laser spot position Are previously associated with the respective light receiving element positions. This correspondence is stored in the conversion table memory 13 as a conversion table.
[0037]
The conversion table is created by fixing the scanning position (laser spot position) of the scanning mirror 4 for every laser spot position on the scanning surface in FIG. 7 and examining the light receiving element position where the output is maximum at that scanning position. I do. The correspondence between the laser spot position and the light receiving element position obtained by this operation is stored in the conversion table memory 13 as a conversion table.
[0038]
Now, when the laser beam scanned by the scanning mirror 4 is at the scanning position Sxy in the scanning plane of FIG. 7, the light receiving element position on the light receiving element array 8 at which the reflected light at this scanning position Sxy is received is shown in FIG. Dxy. In this case, when the scanning position information indicating the scanning position Sxy is input from the scanning mirror controller 5 to the distance measurement control circuit 12, the distance measurement control circuit 12 uses the conversion table in the conversion table memory 13 to detect the light receiving element corresponding to the scanning position Sxy. The light receiving element position Dxy on the array 8 is obtained. The light-receiving element position Dxy and its surrounding light-receiving element positions D (x + 1) y, D (x-1) y, Dx (y + 1), and Dx (y-1) are output to the multiplexer 9 with a selection command. Numeral 9 selects and inputs the outputs of the light receiving elements at the positions Dxy, D (x + 1) y, D (x-1) y, Dx (y + 1), and Dx (y-1). Output.
[0039]
Here, not only the position Dxy but also the surrounding positions D (x + 1) y, D (x-1) y, Dx (y + 1), and Dx (y-1) are selected and added because the laser spot is scanned. In the case of including the vicinity of the boundary between the position Sxy and the scanning positions S (x + 1) y, S (x-1) y, Sx (y + 1), and Sx (y-1) around the position Sxy, the position D (x + 1) around the position Dxy This is because a sufficient light receiving level is ensured by adding the outputs of the light receiving elements of y, D (x-1) y, Dx (y + 1), and Dx (y-1). As a result, even if a mirror having a small mirror area such as a semiconductor mirror is used as the scanning mirror 4, a light receiving level sufficient to detect a light receiving signal can be secured.
[0040]
The light receiving output addition amplifier 10 adds the input light receiving outputs and inputs the added light receiving output to the data measurement circuit 11. The data measurement circuit 11 outputs the count value of the counter 41 to the distance measurement control circuit 12 as measurement data in the case of the configuration of FIG. 4, and uses the voltage data of the integrator 52 as measurement data in the case of the configuration of FIG. Output to the control circuit 12. If the reflected light is received at this scanning position, the data value of the data measurement circuit 11 is reset by the received light output before the input of the next light transmission pulse generation information. The distance measurement control circuit 12 determines the presence or absence of the reflected light from the object A based on whether or not the data value of the data measurement circuit 11 has been reset before the input of the next light transmission pulse generation information. When the data value is reset before the input of the pulse generation information, the distance to the object A is calculated based on the measurement data of the data measurement circuit 11.
[0041]
According to such a configuration, even if the viewing angle of the light receiving system is expanded using an imaging lens having a wide angle of view, the presence or absence of light reception is monitored only for incident light from an extremely narrow laser spot range in the scanning area. Therefore, an S / N ratio equal to or higher than that of the conventional coaxial type can be obtained, and sufficient object detection accuracy can be secured. In addition, the field of view for monitoring the object can be greatly expanded. Further, by using the conversion table, errors due to the aberration of the imaging lens 7, errors due to mismatch between the optical axes of transmitting and receiving the laser light, errors due to optical distortion due to the incident angle of the laser light to the scanning mirror, and the like are corrected. As a result, an accurate light receiving position can be obtained, and the accuracy of object detection and ranging can be improved. Furthermore, if a semiconductor mirror is used as the scanning mirror 4, the size and weight of the laser radar can be reduced, which is effective when used in a vehicle-mounted device mounted on a moving body. If the conversion table is periodically updated, it is possible to calibrate the shift of the light receiving position due to a change over time or the like, and to maintain the accuracy of object detection and distance measurement.
[0042]
Needless to say, the scanning by the scanning mirror 4 is not limited to two-dimensional, but may be one-dimensional.
Next, a second embodiment of the present invention will be described.
[0043]
FIG. 8 shows a configuration diagram of the second embodiment. The same elements as those in the first embodiment are denoted by the same reference numerals.
8, the scanning laser radar 1 according to the second embodiment includes an A / D converter 14, a sampling clock generator 15, and a waveform data memory 16 in addition to the configuration of the first embodiment.
[0044]
The A / D converter 14 samples the output value of the light receiving output adding amplifier 10 every time the sampling clock of the sampling clock generator 15 is input, converts the analog signal from the light receiving output adding amplifier 10 into a digital signal, and measures it. It is sent to the distance control circuit 12. Here, the A / D converter 14 and the sampling clock generator 15 constitute an A / D converter.
[0045]
The distance measurement control circuit 12 generates the waveform data of the light receiving output in one scanning cycle of the scanning mirror 4 from the digital signal input from the A / D converter 14 based on the scanning position information from the scanning mirror controller 5 and generates the waveform data. It is stored in the memory 16. Further, each time the next waveform data is input, the ranging control circuit 12 performs averaging with the waveform data stored in the waveform data memory 16 and performs a new averaging process on the waveform data in the waveform data memory 16. Rewrite with waveform data and update. Here, the distance measurement control circuit 12 of the present embodiment has a function of an averaging processing means.
[0046]
Note that the distance measurement control circuit 12 of the second embodiment has the function of the data measurement circuit 11 of the first embodiment. The distance measurement control circuit 12 measures the time from the generation of the light transmission pulse to the generation of the light receiving output based on the light transmission pulse generation information from the laser drive circuit 3 and the waveform data information stored in the waveform data memory 16. The distance to the object A is calculated based on the measured value.
[0047]
Next, the operation of the second embodiment will be described.
The operation is the same as that of the first embodiment until the laser light is scanned by the scanning mirror 4 and the light receiving output of the light receiving element array 8 is added by the light receiving output adding amplifier 10. In the second embodiment, an output signal from the light receiving output addition amplifier 10 is converted into a digital signal by the A / D converter 14 and input to the distance measurement control circuit 12. The distance measurement control circuit 12 obtains waveform data of one scanning cycle of the scanning mirror 4 based on the scanning position information from the scanning mirror controller 5, and stores the waveform data stored in the waveform data memory 16 every time new waveform data is obtained. And the waveform data in the waveform data memory 16 is updated.
[0048]
For example, when the sampling clock frequency is 1 GHz, in one scanning cycle of the scanning mirror 4, reception waveform data by sampling data every 1 nsec as shown in FIG. 9A is obtained. By performing an averaging process on the received waveform data, the noise component included in the waveform data is reduced, and the reflected light component of the laser beam is increased. As shown in FIG. can get.
[0049]
The distance measurement control circuit 12 uses the waveform data obtained by performing the averaging process a predetermined number of times, and if the waveform data includes a light reception output, the light transmission to the scanning position of the scanning mirror 4 from which the light reception output was obtained. The time T is calculated based on the pulse generation information and the light receiving output information of the waveform data, and the distance to the object A is calculated.
[0050]
According to the configuration of the second embodiment, when the scanning laser radar according to the present invention is used as a sufficient laser radar having a low scanning speed used for monitoring an object other than a moving object, for example, a road surface or a room, Even if a semiconductor mirror having a high scanning speed (typically 1 kHz or more) as shown in FIG. 2 is used as the scanning mirror 4, a sufficient S / N ratio can be obtained, and high-precision and wide-range object monitoring can be performed. it can. By using a semiconductor mirror, this type of low-speed scanning laser radar can be reduced in size and weight.
[0051]
Next, a third embodiment of the present invention will be described.
FIG. 10 shows a configuration diagram of the third embodiment. Note that the same elements as those in the second embodiment are denoted by the same reference numerals.
[0052]
In FIG. 10, the scanning laser radar 1 according to the third embodiment, except for the waveform data memory 16 according to the second embodiment, serves as a multiple pulse generation circuit 17, an A / D conversion value memory 18, and a firing pulse number table storage means. Is added to the firing pulse number table memory 19.
[0053]
For example, as shown in FIG. 11, the multiple pulse generating circuit 17 includes a plurality of switch elements (for example, power MOSFETs) 17-1 to 17-i, capacitors C1 to Ci, and the like. As shown in FIG. 12, the plurality of trigger pulses Tp1 to Tpi sequentially output from the laser drive circuit 3, for example, at a constant interval, sequentially turn on the switch elements 17-1 to 17-i, thereby causing a plurality of light transmissions in a transmission section. The configuration is such that a pulse Ip is generated and output to the laser light source 2. Here, a laser light source driving unit is constituted by the plural pulse generating circuit 17 and the laser driving circuit 3.
[0054]
The A / D conversion value memory 18 stores the digital value of the light receiving output from the A / D converter 14, and stores the light receiving output state of each scanning position of the scanning mirror 4.
The distance measurement control circuit 12 of the present embodiment fetches the received light waveform stored in the A / D conversion value memory 18 every time the scanning position changes based on the scanning position information from the scanning mirror controller 5, Calculates the correlation value between the transmitted light waveform of the laser light obtained from the trigger pulse generation information and the received light reception waveform. When the correlation value is equal to or greater than a preset threshold value, it is determined that there is a light reception output, and the maximum correlation value Then, the distance to the object is calculated based on the deviation amount. Here, the distance measurement control circuit 12 of the present embodiment has a function of a correlation value calculation unit.
[0055]
The firing pulse number table memory 19 stores the correspondence between the scanning direction of the scanning mirror 4 and the number of firing pulses. In this firing pulse number table, the scanning position of the scanning mirror 4 (the above-described laser spot position) is fixed, and the number of firing pulses is varied to check the number of firing pulses at which a received light output is obtained. This operation is performed for all laser spot positions on the scanning plane in FIG. A small number of firing pulses is set for an object having a high reflectance, and a large number of firing pulses is set for an object having a low reflectance.
[0056]
The firing pulse number table is used when the scanning laser radar of the present invention is used for a monitoring device such as an indoor device where the environment of the monitoring area hardly changes. It is unnecessary when used. When used outdoors, such as in an in-vehicle device, a configuration is adopted in which a predetermined number of a plurality of light-transmitting pulses are emitted so that a sufficient light-receiving output can be obtained regardless of the scanning direction of the scanning mirror 4.
[0057]
Next, a case where the third embodiment of the present invention is applied to an in-vehicle device will be described.
When the power is turned on, an operation start command is output from the distance measurement control circuit 12 to the laser driving circuit 3 and the scanning mirror controller 5, and a plurality of preset trigger pulses are generated from the laser driving circuit 3 at each scanning position of the scanning mirror 4. The scanning light source 2 irradiates the scanning mirror 4 with a plurality of laser beams by inputting the plurality of light transmission pulses Ip from the plurality of pulse generation circuits 17. Therefore, a plurality of laser beams are applied to each scanning position of the scanning mirror 4. Further, trigger pulse generation information is input from the laser drive circuit 3 to the distance measurement control circuit 12.
[0058]
On the other hand, in the light receiving system, the output of the light receiving element array 8 is selected by the multiplexer 9 based on the scanning position information of the scanning mirror 4 in the same manner as in the first and second embodiments. The A / D converter 14 converts the added light reception output into a digital signal and stores the digital signal in the A / D conversion value memory 18. Each time the scanning position of the scanning mirror 4 changes, the distance measurement control circuit 12 fetches the received light waveform in the A / D conversion value memory 18, and correlates the transmitted light waveform of the laser light with the scanned position and the received light waveform. Is calculated. Specifically, the correlation value with the received light waveform is obtained while shifting the transmitted light waveform by a predetermined amount Δt for each sampling clock. If the received light output exists, the correlation value becomes maximum when the transmitted light waveform and the received light waveform match as shown in FIG. 13, and the amount of deviation at that time is the time T from the generation of the transmitted light pulse until the received light output is obtained. Since it is proportional, the time T is obtained from the shift amount, and the distance to the object A is calculated. If there is no light reception output, the correlation value between the light transmission waveform and the light reception waveform does not exceed the threshold, and it is determined that there is no light reception output, and the distance is not calculated.
[0059]
As in the third embodiment, a laser beam is irradiated to each scanning position of the scanning mirror 4 a plurality of times, and the presence or absence of a light reception output is determined based on the correlation value between the light transmission waveform and the light reception waveform at that time. Then, if the laser beam is irradiated n times compared to the case where the laser beam is irradiated only once (n- (n) ^1/2 ), The S / N ratio is improved, and the detection accuracy and the distance measurement accuracy of the object can be improved. When the laser beam is irradiated n times, the signal component is proportional to the number of irradiation pulses, but the noise component cancels each other (n). ^1/2 This is because it can only be doubled.
[0060]
When used in a monitoring device such as an indoor room where the environment of the monitoring area hardly changes, a scan pulse number table stored in the fire pulse number table memory 19 based on the scan position information of the scan mirror 4 is used at that scan position. The number of emission pulses is determined, and the required minimum number of laser beams set for each scanning position are emitted. Thereby, the adverse effect of laser light on humans can be reduced and safety can be improved.
[0061]
In the third embodiment, all the switch elements 17-1 to 17-i in the multiple pulse generation circuit 17 are turned on to generate a plurality of light transmission pulses, but some of them are not turned on. Accordingly, the light transmission pulse train may be transmitted after being subjected to code modulation such as "10011 ...".
[0062]
【The invention's effect】
As described above, according to the present invention, an optical image of a scanning region of laser light is formed on a light receiving unit including a large number of light receiving elements using an imaging lens, and the light receiving element is adjusted in accordance with the scanning position of the laser light. Is limited to take out the received light output by the reflected light, so that a sufficient S / N ratio can be secured even if the field of view of the light receiving system is widened, and the monitoring area of the scanning laser radar can be expanded.
[0063]
Further, the light receiving output is digitally averaged, or a plurality of laser beams are emitted for each scanning position, and the correlation value between the transmission pulse waveform and the light receiving output waveform at that time is obtained to obtain the light receiving output. Therefore, when the present invention is applied to a low-speed scanning type monitoring device that does not require a high scanning speed, a sufficient S / N ratio can be obtained even when a semiconductor mirror having a high scanning speed is used for the optical scanning means.
[0064]
Further, by variably controlling the number of laser beams emitted according to the scanning position and minimizing the number of laser beams emitted, adverse effects of the laser beam on humans can be reduced and safety can be improved.
[0065]
If an extremely small and light semiconductor mirror is used for the optical scanning means, the scanning laser radar can be made much smaller and lighter.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a first embodiment of a scanning laser radar according to the present invention.
FIG. 2 is a plan view of a semiconductor mirror used for the scanning mirror according to the embodiment;
FIG. 3 is a diagram showing a relationship between a light transmission pulse and a reception signal.
FIG. 4 is a configuration diagram illustrating an example of a data measurement circuit.
FIG. 5 is a configuration diagram showing another example of the data measurement circuit.
FIG. 6 shows a light receiving element array.
FIG. 7 is a diagram showing a relationship between a laser light scanning surface and a laser spot.
FIG. 8 is a configuration diagram of a second embodiment of the scanning laser radar according to the present invention.
9A is a reception waveform chart in one scanning cycle, and FIG. 9B is a reception waveform chart after averaging processing;
FIG. 10 is a configuration diagram of a third embodiment of the scanning laser radar according to the present invention.
FIG. 11 is a main part circuit diagram of a multiple pulse generation circuit.
FIG. 12 is a diagram showing a relationship between a trigger pulse and a light transmission pulse.
FIG. 13 is a diagram showing a relationship among a light transmission waveform, a light reception waveform, and a correlation value.
[Explanation of symbols]
1 Scanning laser radar
2 Laser light source
3 Laser drive circuit
4 Scanning mirror
5 Scanning mirror controller
6 Optical filter
7 Imaging lens
8 Photodetector array
9 Multiplexer
10 Received light output summing amplifier
11 Data measurement circuit
12 Distance measurement control circuit
13 Conversion table memory
14 A / D converter
15 Sampling clock generator
16 Waveform data memory
17 Multiple pulse generation circuit
18 A / D conversion value memory
19 Launch pulse number table memory

Claims

In a scanning laser radar that scans laser light from a laser light source with optical scanning means, receives reflected light from a scanning region on a different optical path from the scanning laser light, and monitors the inside of the scanning region,
A number of light receiving elements are arranged in a matrix and light receiving means for receiving reflected light from the scanning area via an imaging lens,
Light-receiving element selecting means for selecting a plurality of light-receiving elements specified from the light-receiving elements of the light-receiving means,
Each time the scanning position of the light scanning means changes, a light-receiving element previously associated with the scanning position and a command to select a light-receiving element around the light-receiving element are output to the light-receiving element selecting means and a plurality of light-receiving elements are selected. Control means for controlling switching;
Light receiving output adding means for adding the light receiving output of the light receiving element selected by the light receiving element selecting means,
A scanning laser radar, wherein the inside of a scanning area is monitored based on the added light receiving output of said light receiving output adding means.

Elapsed time measuring means for measuring an elapsed time from when the laser light is emitted from the laser light source to when the added light receiving output of the light receiving output adding means is input, based on information indicating the measuring time of the elapsed time measuring means. 2. The scanning laser radar according to claim 1, further comprising a distance calculating unit that calculates a distance to an object in the scanning area.

A / D conversion means for A / D converting the output of the light reception output addition means, and light reception waveform data per scanning cycle of the light scanning means obtained based on a digital output of the A / D conversion means are predetermined. 2. The scanning laser radar according to claim 1, further comprising an averaging means for performing averaging processing of the number of scanning cycles, and monitoring the inside of the scanning area based on the received light waveform data obtained by the averaging processing.

Laser light source driving means for outputting a plurality of light transmission pulses to the laser light source for each scanning position of the light scanning means to emit laser light a plurality of times, and A / D converting the output of the light receiving output adding means; A / D conversion means for performing the above operation and shifting the waveform data of the light transmission pulse of the laser light source driving means by a predetermined amount at predetermined time intervals for each scanning position of the optical scanning means, 2. The scanning device according to claim 1, further comprising: a correlation value calculating unit configured to calculate a correlation value with the waveform data, wherein a distance to an object in the scanning area is calculated based on a shift amount when the correlation value becomes maximum. Type laser radar.

5. The configuration according to claim 4, wherein the number of light transmission pulses of the laser light source driving unit is variably controlled in accordance with each scanning position of the optical scanning unit, and the number of times of emitting laser light is variably controlled in accordance with each scanning position. Scanning laser radar.

FIG. 6 shows a correspondence relationship between each scanning position and the number of light transmission pulses created by previously obtaining the number of laser light emission times at which the light scanning means is fixed at each scanning position and emits laser light and the light receiving output is detected at each scanning position. A firing pulse number table storing means for storing a firing pulse number table is provided, and the laser light source drive is performed based on the firing pulse number table stored in the firing pulse number table storing means when scanning position information of the optical scanning means is input. 6. The scanning laser radar according to claim 5, wherein the number of light transmission pulses of the means is determined.

The light scanning means is fixed at each scanning position, emits a laser beam, and at each scanning position, among the respective light receiving elements of the light receiving means, a light receiving element having a maximum light receiving output is determined in advance to obtain each scanning position and each scanning position. A conversion table storing unit that stores a conversion table indicating a correspondence relationship between light receiving element positions; wherein the control unit is configured to store a conversion table based on the conversion table stored in the conversion table storage unit when scanning position information of the optical scanning unit is input. The scanning laser radar according to claim 1, wherein a position of a plurality of light receiving elements to be selected is determined.

The scanning laser radar according to claim 7, wherein the conversion table is updated periodically.

The scanning laser radar according to any one of claims 1 to 8, wherein a semiconductor mirror manufactured by a semiconductor micromachine technique is used for the optical scanning means.