JP3930164B2 - Wavelength selective LCD camera device - Google Patents

Description

【表２】

【００４０】
前記画像処理部３は、図４に示すように、ヘッドアンプ回路１５と、映像処理回路１６と、Ａ／Ｄ変換回路１７を備えている。ヘッドアンプ回路１５は、波長選択光学系２から順次出力される短波長域映像信号、長波長域映像信号を一定の増幅率で増幅する。映像処理回路１６は、ヘッドアンプ回路１５から順次出力される短波長域映像信号、長波長域映像信号に対し、予め設定されている画像処理、例えば液晶フィルタ５の透過領域補償処理や、液晶フィルタ５の透過率補償処理などを行う。Ａ／Ｄ変換回路１７は、映像処理回路１６から順次出力される短波長域映像信号、長波長域映像信号をＡ／Ｄ変換して、デジタル化された短波長域映像信号、長波長域映像信号を生成して差画像抽出部４に供給する。
【００４１】
前記差画像抽出部４は、フレームメモリ回路１８と、差分回路１９と、絶対値回路２０と、Ｄ／Ａ変換回路２１と、増幅回路２２とを備えている。フレームメモリ回路１８は、入力されている垂直同期信号に基づき、画像処理部３から出力されるデジタル化された短波長域映像信号、長波長域映像信号のうち、予め設定されている波長領域の映像信号、例えば短波長域映像信号をフレーム単位で取り込んで記憶する一方、画像処理部３から長波長域映像信号が出力されたときにはこれに同期して、記憶している短波長域映像信号を出力する。差分回路１９は、入力される垂直同期信号に基づき、フレームメモリ回路１８から出力される短波長域映像信号と画像処理部３から出力されるデジタル化された長波長域映像信号とを画素単位で比較し、同じ空間座標の各画素同士のレベル差を演算して前記短波長域映像信号と長波長域映像信号との差を示す映像信号、例えば、水面に浮かんだ油膜の映像や有機膜の映像などのコントラストを高くした映像信号を生成する。絶対値回路２０は、差分回路１９から出力される映像信号の絶対値を演算する。Ｄ／Ａ変換回路２１は、絶対値回路２０から出力されるデジタル信号形式の映像信号をアナログ信号形式の映像信号に変換する。増幅回路２２は、Ｄ／Ａ変換回路２１から出力される映像信号を増幅してディスプレイ装置に供給する。
【００４２】
次に、図１〜図５を参照しながら、この実施の形態の動作について説明する。
【００４３】
まず、波長選択型液晶カメラ装置１によって、油膜が浮かんだ海面などを撮影すると、波長選択型液晶カメラ装置１内に設けられている波長選択光学系２の液晶フィルタ５によって、被写体からの光像（白色の光像）が取り込まれるとともに、入力交流電圧に応じて、光像を構成する短波長域の光像と、光像を構成する長波長域の光像とが順次サイクリックに抽出される。
【００４４】
そして、レンズ６によって撮像素子７上に結像され、これによって得られた短波長域映像信号と、長波長域映像信号とが画像処理部３に順次供給されて、これら短波長域映像信号、長波長域映像信号に対し、前置増幅処理、液晶フィルタ５の透過領域補償処理、液晶フィルタ５の透過率補償処理などが行われ、これによって得られた短波長域映像信号、長波長域映像信号がデジタル化されて、差画像抽出部４に供給される。
【００４５】
この場合、図３の（ｂ）に示すように、映像信号のフレームＡ、Ｃ、Ｅ、Ｇ、Ｉのときには、図３の（ａ）に示すように、液晶フィルタ５にバースト状の交流電圧が印加されている。このため、液晶層１４を構成している液晶の屈折率が変化し、一種のファブリ・ペロー干渉計となっている液晶フィルタ５の中心周波数が変化して、被写体からの光像を構成している各波長域の光像のうち、短波長域に属する複数の光像が抽出され、これが撮像素子７上に結像されて短波長域映像信号が生成され、これが画像処理部３に供給される。
【００４６】
また、図３の（ｂ）に示すように、映像信号のフレームＢ、Ｄ、Ｆ、Ｈ、Ｊのときには、図３の（ａ）に示すように、液晶フィルタ５にバースト状の交流電圧は印加されていない。このため、液晶層１４を構成している液晶の屈折率は元に戻り、一種のファブリ・ペロー干渉計となっている液晶フィルタ５の中心周波数が変化して、被写体からの光像を構成している各波長域の光像のうち、長波長域に属する各光像が抽出され、これが撮像素子７上に結像されて長波長域映像信号が生成され、これが画像処理部３に供給される。
【００４７】
そして、画像処理部３からデジタル化された短波長域映像信号が出力されたとき、入力されている垂直同期信号に基づき、差画像抽出部４のフレームメモリ回路１８によって、短波長域映像信号が取り込まれて記憶された後、画像処理部３からデジタル化された長波長域映像信号が出力されたとき、差分回路１９、絶対値回路２０によって、この長波長域映像信号と、フレームメモリ回路１８に記憶されている短波長域映像信号とが画素単位で比較されて、同じ空間座標の各画素同士のレベル差が演算され、これによって得られた短波長域映像信号と、長波長域映像信号との絶対差｜Ａ−Ｂ｜、｜Ｂ−Ｃ｜、｜Ｃ−Ｄ｜、｜Ｄ−Ｅ｜、｜Ｅ−Ｆ｜、…を示す映像信号（例えば、水面に浮かんだ油膜の映像や有機膜の映像などのコントラストを高くした映像信号）が生成されるとともに、Ｄ／Ａ変換回路２１、増幅回路２２によって映像信号がアナログ化されて、ディスプレイ装置に供給される。
【００４８】
この際、液晶フィルタ５として、“１．５”の常光屈折率と、“１．７”の異常光屈折率とを持つ厚さ２μｍのホメオトロピック配向のネマチック液晶を用い、さらに各誘電体多層膜１０、１３のパワー反射率を０．９にした液晶フィルタを使用し、この液晶フィルタ５によって異常光のみが偏光板で選択されると仮定すると、液晶フィルタ５にバースト状の交流電圧を印加する前、液晶分子が各透明基板８、１１にほぼ垂直に配向した状態になって、図５の（ｆ）に太い実線で示すように、短波長領域から長波長領域に渡り、約２ｎｍの半値全幅（図５では、簡単にするため、直線で近似している）を持つ複数の透過領域を得ることができ、また異常光が“１．５３”の実効屈折率を感じるように、液晶フィルタ５にバースト状の交流電圧を印加したとき、図５の（ｆ）に細い実線で示すように、短波長領域から長波長領域に渡り、約２ｎｍの半値全幅（図５では、簡単にするため、直線で近似している）を持つ複数の透過領域を得ることができる。
【００４９】
そして、厳密には、海水の屈折率分散により反射率が変化するもの、表１に示す水の屈折率分散例から分かるように、その変化量が非常に小さいことから、表２の上段に示す波長領域のとき、水の屈折率分散を無視しても良く、また図５（ａ）〜（ｅ）に示すように、油面の無い海面の反射率が波長依存性を殆ど持たないことから、液晶フィルタ５の中心波長の移動範囲（図５の（ｆ）に示す太い実線と、細い実線のスペクトル差）が表２の下段範囲内であれば、波長が違っても、液晶フィルタ５によって選択される光像が同じレベルになる。
【００５０】
これにより、海面上に油膜が無いときには、画像処理部３から出力される短波長域映像信号と、長波長域映像信号とが画素単位で同じレベルになって、差画像抽出部４からゼロを示す映像信号が出力される。
【００５１】
一方、図５（ａ）〜（ｅ）に示すように、油膜がある海水では、入射角度がどのような角度でも、波長に応じて油膜の反射率が大きく変化するものの、交流電圧が印加されているとき、液晶フィルタ５を透過する光像の中心波長の透過率（最大透過率）に対し、１／ｅ以上の透過率を持つ波長領域の反射率と、交流電圧が印加されていないとき、液晶フィルタ５を透過する光像の中心波長の透過率（最大透過率）に対し、１／ｅ以上の透過率を持つ波長領域の反射率とが異なるレベルになっていることから、油面がある海水面を撮影したとき、画像処理部３から出力される短波長域映像信号と、長波長域映像信号とが画素単位で異なるレベルになり、差画像抽出部４から油膜を示す映像信号が出力される。
【００５２】
この際、液晶フィルタ５から出力される短波長域の光像と、長波長域の光像とのフレーム時間差が１／３０秒であり、この時間内では、通常、海面が殆ど静止していると見なすことができることから、短波長域映像信号を構成する各画素と、長波長域映像信号を構成する各画素とについて、同じ空間座標を持つ画素毎の演算を行うことができ、また強風のために海面が波立っている場合でも、数画素だけ離れた近傍画素毎に、２フレーム間のレベル差を演算していると考えられ、さらにこの範囲内では、入射角度が大きく変化しないことから、海面が穏やかな場合でも、また強風などにより波立っている場合でも、海面上の油膜を検出することができる。
【００５３】
このように、この実施の形態では、波長選択光学系２によって、油膜が浮かんだ海面などを撮影して、短波長域映像信号と、長波長域映像信号とを順次サイクリックに生成しながら、画像処理部３によって短波長域映像信号と、長波長域映像信号とを画像処理して、デジタル化した短波長域映像信号と、デジタル化した長波長域映像信号とを生成するとともに、差画像抽出部４によって短波長域映像信号と、長波長域映像信号との差を抽出し、水面に浮かんだ油膜の映像や有機膜の映像などのコントラストを高くした映像信号を生成して、これをディスプレイ装置に供給するようにしているので、従来、検出が困難であった水面上の油膜や有機膜などを高いコントラストの画像として検出することができる。
【００５４】
これによって、従来、ヘリコプタや航空機などから目視観察で遭難現場などのを探索しても、油膜の発見が困難な場合、例えば海からの反射光が強い場合（逆光状態）、雨天の場合、波浪が高い場合などでも、海面の状態に関わらず、遭難した航空機や船舶などの油膜が海面上に浮いているとき、これを確実に検出して、遭難現場などを見つけ出すことができる。
【００５５】
また、この実施の形態では、撮影した海面などに油膜や有機膜などがあるときにのみ、差画像抽出部４から出力される映像信号がゼロ以外の値になるようにしているので、差画像抽出部４から出力される映像信号を次段装置などに設けられた判定回路に導き、予め設定されているしきい値を越えているかどうかを判定させるだけで、遭難現場の探索を容易に自動化することができる。これによって、ヘリコプタや航空機などに、図１に示す波長選択型液晶カメラ装置１を複数、搭載し、各波長選択型液晶カメラ装置１によって、全方位を同時に探索させて、油膜などの有無を自動判定させれば、従来の目視による場合に比べて、格段に探索効率を向上させて、迅速な災害救助を行うことができる。
【００５６】
また、図１に示す波長選択型液晶カメラ装置１と、ＧＰＳ（Global Positioning System）装置とを組み合わせることにより、油膜の位置を瞬時に決定することができ、これによって遭難現場などの発見を一層、迅速化させることができるとともに、タンカーなどの原油流出状況をリアルタイムで、容易に地図化することができる。
【００５７】
＜第１の実施の形態の第１変形例＞
また、図１に示す波長選択型液晶カメラ装置１では、液晶フィルタ５によって被写体からの光像に含まれている短波長域の光像と、長波長域の光像とを交互に抽出し、レンズ６によって、これら短波長域の光像と、長波長域の光像とを撮像素子７上に結像させるようにしているが、図６に示すように、撮像素子７の前に、光学的バンドパスフィルタ２３を配置した波長選択光学系２ａを使用し、光学的バンドパスフィルタ２３によって、液晶フィルタ５で選択された短波長域の光像と、長波長域の光像とをバンドパスフィルタリングして、波長範囲を絞り込んで、撮像素子７上に結像させるようにしても良い。
【００５８】
但し、この光学的バンドパスフィルタ２３の半値全幅（Full width Half Maximum）を液晶フィルタ５の半値全幅より広くすることが必要である。
【００５９】
このようにしても、図１に示す波長選択型液晶カメラ装置１と同様に、従来、検出が困難であった水面上の油膜や有機膜などを高いコントラストで画像として検出することができる。
【００６０】
また、この第１変形例では、レンズ６と、撮像素子７との間に、光学的バンドパスフィルタ２３を配置するようにしているが、撮像素子７の前であれば、液晶フィルタ５の前に光学的バンドパスフィルタ２３を配置しても、また液晶フィルタ５の後ろに、光学的バンドパスフィルタ２３を配置しても、この第１変形例と同じ効果を得ることができる。
【００６１】
＜第１の実施の形態の第２変形例＞
また、図１に示す波長選択型液晶カメラ装置１では、交流電圧を印加していないとき、液晶の常光屈折率だけを感じる光線を選択し、また交流電圧を印加しているとき、常光屈折率と異常光屈折率との両方に感じる光線を選択して、各光線を撮像素子７に入射させるようにしているが、図７に示すように、液晶フィルタ５の後ろに、偏光フィルム（あるいは、偏光板）２４を配置した波長選択光学系２ｂを使用し、偏光フィルム２４によって、常光屈折率だけを感じる光線を取り除いて、撮像素子７に入射させるようにしても良い。
【００６２】
このようにしても、図１に示す波長選択型液晶カメラ装置１と同様に、従来、検出が困難であった水面上の油膜や有機膜などを高いコントラストで画像として検出することができる。
【００６３】
また、この第２変形例では、液晶フィルタ５と、レンズ６との間に、偏光フィルム２４を配置するようにしているが、撮像素子７の前であれば、液晶フィルタ５の前やレンズ６の後ろに偏光フィルム２４を配置しても、この第２変形例と同じ効果を得ることができる。
【００６４】
＜第１の実施の形態の第３変形例＞
また、図１に示す波長選択型液晶カメラ装置１では、波長選択型光学系２と、画像処理部３と、差画像抽出部４とを１つの筐体内に入れてカメラ装置を構成するようにしているが、差画像抽出部４の全てと、画像処理部３の全てまたは一部とをカメラ装置から分離するようにしても良い。
【００６５】
このようにすることにより、カメラ装置部分を小型、軽量化して、カメラ装置の取扱いや操作などを容易にすることができる。
【００６６】
《発明の第２の実施の形態の説明》
＜第２の実施の形態の基本説明＞
図８は本発明による波長選択型液晶カメラ装置の第２の実施の形態を示すブロック図である。なお、この図においては、説明を簡単にするために、本発明の説明に係わりのない部分、例えば入射光量を減衰させるアイリスやＮＤフィルタなど、カメラ装置を構成するのに必要な部品、駆動回路、映像処理回路などにパルス信号を送るパルス発生回路、映像の輪郭を強調する輪郭補償回路、電源回路などを省略してある。
【００６７】
この図に示す波長選択型液晶カメラ装置３０は、波長選択光学系３１と、短波長側画像処理部３２と、短波長側差画像抽出部３３と、長波長側画像処理部３４と、長波長側差画像抽出部３５と、映像合成部３６とを備えている。波長選択光学系３１は、被写体からの光像を取り込んで２等分するとともに、短波長域の光像、および長波長域の光像を抽出して光電変換し、短波長側映像信号、および長波長領域の光像に対する長波長側映像信号をそれぞれ生成する。短波長側画像処理部３２は、波長選択光学系３１から順次出力される短波長側映像信号を画像処理してデジタル化した短波長側映像信号を順次生成する。短波長側差画像抽出部３３は、短波長側画像処理部３２から出力される短波長側映像信号をフレーム単位で記憶しながら、現フレームの短波長側映像信号と１フレーム前の短波長側映像信号との差に基づき、海面や水面などに浮かんだ油膜の映像や有機膜の映像などのコントラストを高くした短波長側映像信号を生成して映像合成部３６に供給する。長波長側画像処理部３４は、波長選択光学系３１から順次出力される長波長側映像信号を画像処理してデジタル化した長波長側映像信号を順次生成する。長波長側差画像抽出部３５は、この長波長側画像処理部３４から出力される長波長側映像信号をフレーム単位で記憶しながら、現フレームの長波長側映像信号と１フレーム前の長波長側映像信号との差に基づき、海面や水面などに浮かんだ油膜の映像や有機膜の映像などのコントラストを高くした長波長側映像信号を生成する。映像合成部３６は、短波長側差画像抽出部３３から出力される短波長側映像信号と、長波長側差画像抽出部３５から出力される長波長側映像信号とを加算して合成テレビ信号を生成する。
【００６８】
前記波長選択光学系３１は、液晶フィルタ３７と、レンズ３８と、ビームスプリッタ４４とを備えている。液晶フィルタ３７は、図１に示す各液晶フィルタ５と同様に構成され、被写体からの光像（白色の光像）を取り込むとともに、入力される交流電圧に応じて、短波長域の光像、長波長域の光像を抽出する。レンズ３８は、液晶フィルタ３７によって選択された短波長域の光像、長波長域の光像を集光しながら、所定距離だけ後方に結像させる。ビームスプリッタ４４は、入射面３９に入射された短波長域の光像の半分、長波長域の光像の半分を透過させて、第２出射面４０から出射させるとともに、短波長域の光像の残り半分、長波長域の光像の残り半分を反射させる反射透過面４１、この反射透過面４１で反射された短波長域の光像、長波長域の光像を全反射させて、第１出射面４２から、第２出射面４０から出射される短波長域の光像、長波長域の光像と同じ左右方向となった短波長域の光像、長波長域の光像を出射させる全反射面４３を有し、レンズ３８によって集光された短波長域の光像、長波長域の光像を２等分して、第１出射面４２、第２出射面４０からそれぞれ出力する。
【００６９】
さらに、波長選択光学系３１は、光学的バンドパスフィルタ４５と、短波長側撮像素子４６と、光学的バンドパスフィルタ４７と、長波長側撮像素子４８とを備えている。光学的バンドパスフィルタ４５は、ビームスプリッタ４４の第１出射面４２から出射される短波長領域側の光像を透過させる。短波長側撮像素子４６は、ＣＣＤ、ＭＯＳ、ＣＰＤ、ＳＩＴ、ＡＭＩなど、シリコンを用いた固体撮像素子またはＧａＡｓ、ＩｎＧａＡｓなど赤外線領域で高い感度を示す材料を用いた固体撮像素子、または非晶質セレンなど、紫外線や短波長可視光で高い感度を示す材料を用いた固体撮像素子、あるいはプランビコン、サチコン、ビジコン、カルニコン、ハーピコンなどの撮像管のいずれかによって構成され、光学的バンドパスフィルタ４５から出射される短波長領域側の光像を光／電変換し、短波長側映像信号を順次サイクリックに生成する。光学的バンドパスフィルタ４７は、ビームスプリッタ４４の第２出射面４０から出射される長波長領域側の光像を透過させる。長波長側撮像素子４８は、短波長側撮像素子４６と同様に構成され、光学的バンドパスフィルタ４７から出射される長波長領域側の光像を光／電変換し、長波長側映像信号を順次サイクリックに生成する。
【００７０】
この際、レンズ３８と短波長側撮像素子４６との間の光路長と、レンズ３８と長波長側撮像素子４８との間の光路長とが等しくなるように、ビームスプリッタ４４内の各光路長が設定される。
【００７１】
短波長側画像処理部３２は、図９に示すように、ヘッドアンプ回路４９と、映像処理回路５０と、Ａ／Ｄ変換回路５１とを備え、波長選択光学系３１から出力される短波長側映像信号に対し、前置増幅処理、液晶フィルタ３７の透過領域補償処理、液晶フィルタ３７の透過率補償処理などを行い、これによって得られた短波長側映像信号をデジタル化して、短波長側差画像抽出部３３に供給する。ヘッドアンプ回路４９は、波長選択光学系３１から順次出力される短波長側映像信号を一定の増幅率で増幅する。映像処理回路５０は、ヘッドアンプ回路４９から順次出力される短波長側映像信号に対し、予め設定されている画像処理、例えば液晶フィルタ３７の透過領域補償、液晶フィルタ３７の透過率補償などを行う。Ａ／Ｄ変換回路５１は、映像処理回路５０から順次出力される短波長側映像信号をＡ／Ｄ変換して、デジタル化された短波長側映像信号を生成する。
【００７２】
短波長側差画像抽出部３３は、フレームメモリ回路５２と、差分回路５３と、絶対値回路５４と、Ｄ／Ａ変換回路５５と、増幅回路５６とを備えており、入力されている垂直同期信号に基づき、短波長側画像処理部３２からデジタル化された短波長側映像信号が出力されたとき、これを取り込んで記憶するとともに、短波長側画像処理部３２からデジタル化された短波長側映像信号が出力されたとき、この短波長側映像信号と、記憶している１フレーム前の短波長側映像信号とを画素単位で比較して、同じ空間座標の各画素同士のレベル差を演算して、これによって得られた両信号の差を示す短波長側差分映像信号（例えば、水面に浮かんだ油膜の映像や有機膜の映像などのコントラストを高くした短波長側映像信号）をアナログ化して増幅した後、映像合成部３６に供給する。
【００７３】
また、長波長側画像処理部３４は、図１０に示すように、ヘッドアンプ回路５７と、映像処理回路５８と、Ａ／Ｄ変換回路５９とを備えている。ヘッドアンプ回路５７は、波長選択光学系３１から順次出力される長波長側映像信号を一定の増幅率で増幅する。映像処理回路５８は、ヘッドアンプ回路５７から順次出力される長波長側映像信号に対し、予め設定されている画像処理、例えば液晶フィルタ３７の透過領域補償、液晶フィルタ３７の透過率補償などを行う。Ａ／Ｄ変換回路５９は、映像処理回路５８から順次出力される長波長側映像信号をＡ／Ｄ変換して、デジタル化された長波長側映像信号を生成して長波長側差画像抽出部３５に供給する。
【００７４】
長波長側差画像抽出部３５は、フレームメモリ回路６０と、差分回路６１と、絶対値回路６２と、Ｄ／Ａ変換回路６３と、増幅回路６４とを備え、入力されている垂直同期信号に基づき、長波長側画像処理部３４からデジタル化された長波長側映像信号が出力されたとき、これを取り込んで記憶するとともに、長波長側画像処理部３４からデジタル化された長波長側映像信号が出力されたとき、この長波長側映像信号と、記憶している１フレーム前の長波長側映像信号とを画素単位で比較して、同じ空間座標の各画素同士のレベル差を演算し、これによって得られた長波長側映像信号と長波長側映像信号との差を示す長波長側映像信号（例えば、水面に浮かんだ油膜の映像や有機膜の映像などのコントラストを高くした長波長側映像信号）をアナログ化して増幅した後、映像合成部３６に供給する。
【００７５】
映像合成部３６は、図８に示すように、加算回路６５と、増幅回路６６とを備えている。加算回路６５は、短波長側差画像抽出部３３から出力される短波長側映像信号と、長波長側差画像抽出部３５から出力される長波長側映像信号とを加算して合成テレビ信号を生成する。増幅回路６６は、加算回路６５から出力される合成テレビ信号を増幅してディスプレイ装置などに供給し、これにより油膜像などを画像化する。
【００７６】
このように、この実施の形態では、波長選択光学系３１によって、油膜が浮かんだ海面などを撮影して、短波長側映像信号と、長波長側映像信号とを順次生成しながら、短波長側画像処理部３２、長波長側画像処理部３４によって、短波長側映像信号と、長波長側映像信号とを画像処理して、デジタル化した短波長側映像信号と、長波長側映像信号とを生成した後、短波長側差画像抽出部３３によって短波長側映像信号と、短波長側映像信号との差を抽出して、水面などに浮かんだ油膜の映像や有機膜の映像などのコントラストを高くした短波長側映像信号を生成するとともに、長波長側差画像抽出部３５によって長波長側映像信号と、長波長側映像信号との差を抽出して、水面などに浮かんだ油膜の映像や有機膜の映像などのコントラストを高くした長波長側映像信号を生成し、これらを合成した合成テレビ信号をディスプレイ装置に供給するようにしているので、水面の状態がどのような状態であっても、水面上の油膜や有機膜などを高いコントラストで画像として検出することができる。
【００７７】
これによって、従来、ヘリコプタや航空機などから目視観察で遭難現場などを探索しても、油膜の発見が困難な場合、例えば海面からの反射光が強い場合（逆光状態）、雨天の場合、波浪が高い場合などでも、海面の状態に関わらず、遭難した航空機や船舶などの油膜が海面上に浮いているとき、これを確実に検出して、遭難現場などを見つけ出すことができる。
【００７８】
また、この実施の形態では、撮影した海面などに油膜や有機膜などがあるときにのみ、短波長側差画像抽出部３３、長波長側差画像抽出部３５から出力される短波長側映像信号、長波長側映像信号がゼロ以外の値になるようにしているので、映像合成部３６から出力される合成テレビ信号を判定回路（図示は省略する）に導き、予め設定されているしきい値を越えているかどうかを判定させるだけで、遭難現場の探索を容易に自動化することができる。これによって、ヘリコプタや航空機などに、図８に示す波長選択型液晶カメラ装置３０を複数搭載し、各波長選択型液晶カメラ装置３０によって、全方位を同時に探索させ、油膜などの有無を自動判定させれば、従来の目視による場合に比べて、格段に探索効率を向上させて、迅速な災害救助を行うことができる。
【００７９】
また、図８に示す波長選択型液晶カメラ装置３０と、ＧＰＳ（Global Positioning System）装置とを組み合わせることにより、油膜の位置を瞬時に決定することができ、これによって遭難現場などの発見を一層、迅速化させることができるとともに、タンカーなどの原油流出状況をリアルタイムで、容易に地図化することができる。
【００８０】
＜第２の実施の形態の第１変形例＞
また、図８に示す波長選択型カメラ装置３０では、液晶フィルタ３７と、レンズ３８と、ビームスプリッタ４４と、２つの光学的バンドパスフィルタ４５、４７と、短波長側撮像素子４６と、長波長側撮像素子４８とによって構成される波長選択光学系３１を使用するようにしているが、図１１に示すように、液晶フィルタ３７と、レンズ３８と、プリズム型バンドパスフィルタ６７と、短波長側撮像素子４６と、長波長側撮像素子４８とによって構成される波長選択光学系３１ａを使用するようにしても良い。
【００８１】
この場合、プリズム型バンドパスフィルタ６７は、プリズム６９と、プリズム７４と、光学的ローパスフィルタ７５と、光学的ハイパスフィルタ７７と、光学的ローパスフィルタ７９とを備えている。プリズム６９は、前面６８側が４５度にカットされたプリズムである。プリズム７４は、前面７０（後面７１）と斜面７２、７３とのなす角度が４５度、１３５度になるようにカットされた並行四辺形型のプリズムである。光学的ローパスフィルタ７５は、プリズム７４の斜面７３とプリズム６９の前面６８との接合面に配置され、図１２、図１３に示すようなローパス特性で、入射した光像のうち、長波長領域に属する光像を透過させるとともに、短波長領域に属する光像を反射させる。光学的ハイパスフィルタ７７は、プリズム６９の出射面７６に接合され、図１２に示すように、光学的ローパスフィルタ７５の透過波長特性のカットオフ波長λ_７５（但し、ここでは、光学的ローパスフィルタ７５の透過率が最大透過率の５０％になる波長をカットオフ波長と定義する）より長波長側にシフトしたカットオフ波長特性を持ち、光学的ローパスフィルタ７５を透過した長波長側の光像のうち、カットオフ波長λ_７７より短い波長の光像（斜線部分の光像）を透過させる。光学的ローパスフィルタ７９は、プリズム７４の出射面７８（後面７１）に接合され、図１３に示すように、光学的ローパスフィルタ７５の反射波長特性のカットオフ波長λ_７５より短波長側にシフトしたカットオフ波長λ_７９を持ち、光学的ローパスフィルタ７５で反射された短波長側の光像のうち、カットオフ波長λ_７９より長い波長の光像（斜線部分の光像）を透過させる。
【００８２】
勿論、このプリズム型バンドパスフィルタ６７でも、レンズ３８と短波長側撮像素子４６との間の光路長と、レンズ３８と長波長側撮像素子４８との間の光路長とが同じくなるように、プリズム型バンドパスフィルタ６７内の各光路長が設定される。
【００８３】
この波長選択光学系３１ａにおいては、液晶フィルタ３７によって選択された短波長域の光像、長波長域の光像が出力され、これがレンズ３８によって集光されながら、入射面（前面７０）８０に入射したとき、光学的ローパスフィルタ７５のフィルタリング動作、光学的ハイパスフィルタ７７のフィルタリング動作によって、図１２に示すように、波長λ_ａを中心とする長波長領域に属する光像を選択して、これを長波長側撮像素子４８に入射させ、長波長側映像信号と、長波長側映像信号とを生成させるとともに、光学的ローパスフィルタ７５のフィルタリング動作、光学的ローパスフィルタ７９のフィルタリング動作によって、図１３に示すように、波長λ_ｂを中心とする短波長領域に属する光像を選択して、これを短波長側撮像素子４６に入射させ、短波長側映像信号を生成させる。
【００８４】
このように、液晶フィルタ３７と、レンズ３８と、プリズム型バンドパスフィルタ６７と、短波長側撮像素子４６、長波長側撮像素子４８とによって構成される波長選択光学系３１ａを使用しても、液晶フィルタ３７によって選択された短波長域の光像、長波長域の光像を左右が反転されていない２つの光像に２等分して、短波長側映像信号と、長波長側映像信号とを生成することができる。
【００８５】
＜第２の実施の形態の第２変形例＞
また、図１１に示す第１変形例では、液晶フィルタ３７と、レンズ３８と、プリズム型バンドパスフィルタ６７と、短波長側撮像素子４６、長波長側撮像素子４８とによって波長選択光学系３１ａを構成するようにしているが、図１４に示すように、液晶フィルタ３７と、レンズ３８と、プリズム型ローパスフィルタ８１と、光学的ローパスフィルタ８２と、光学的ハイパスフィルタ８３と、短波長側撮像素子４６と、長波長側撮像素子４８とによって波長選択光学系３１ｂを構成し、この波長選択光学系３１ｂを使用して被写体からの光像を波長弁別し、短波長側映像信号と、長波長側映像信号とを生成するようにしても良い。
【００８６】
この場合、プリズム型ローパスフィルタ８１は、プリズム８５と、プリズム９０と、光学的ローパスフィルタ９１とを備えている。プリズム８５は、前面８４側が４５度にカットされたプリズムである。プリズム９０は、前面８６（後面８７）と斜面８８、８９とのなす角度が４５度、１３５度になるようにカットされた並行四辺形型のプリズムである。光学的ローパスフィルタ９１は、プリズム９０の斜面８９とプリズム８５の前面８４との接合面に配置され、図１１に示す光学的ローパスフィルタ７５と同じローパス特性で、入射した光像のうち、長波長領域に属する光像を透過させるとともに、短波長領域に属する光像を反射させる。
【００８７】
このプリズム型ローパスフィルタ８１では、レンズ３８から短波長域の光像、長波長域の光像が入射面（前面８６）９２に入射したとき、光学的ローパスフィルタ９１のフィルタリング動作によって、長波長側の光像を透過させ、これを出射面９３から出射させて、光学的ハイパスフィルタ８３に入射させるとともに、光学的ローパスフィルタ９１によって、短波長側の光像を反射させた後、これを全反射面９４で反射させて、出射面９５から出射させ、光学的ローパスフィルタ８２に入射させる。
【００８８】
光学的ローパスフィルタ８２は、図１１に示す光学的ローパスフィルタ７９と同様なローパス特性（図１３に示すローパス特性）を持つフィルタ板によって構成されており、プリズム型ローパスフィルタ８１の出射面９５から出射される短波長側の光像のち、図１３に示すように、波長λ_ｂを中心とする短波長側の光像を選択し、これを短波長側撮像素子４６に入射させ、短波長側映像信号を生成させる。
【００８９】
また、光学的ハイパスフィルタ８３は、図１１に示す光学的ハイパスフィルタ７７と同様なハイパス特性（図１２に示すハイパス特性）を持つフィルタ板によって構成されており、プリズム型ローパスフィルタ８１の出射面９３から出射される長波長側の光像のうち、図１２に示すように、波長λ_ａを中心とする長波長側の光像を選択して、これを長波長側撮像素子４８に入射させ、長波長側映像信号を生成させる。
【００９０】
このように、液晶フィルタ３７と、レンズ３８と、プリズム型ローパスフィルタ８１と、光学的ローパスフィルタ８２と、光学的ハイパスフィルタ８３と、短波長側撮像素子４６と、長波長側撮像素子４８とによって構成される波長選択光学系３１ｂを使用しても、被写体からの光像を波長弁別し、短波長側映像信号と、長波長側映像信号とを生成することができる。
【００９１】
＜第２の実施の形態の第３変形例＞
また、図１４に示す第２変形例では、液晶フィルタ３７と、レンズ３８と、プリズム型ローパスフィルタ８１と、光学的ローパスフィルタ８２と、光学的ハイパスフィルタ８３と、短波長側撮像素子４６と、長波長側撮像素子４８とによって波長選択光学系３１ｂを構成するようにしているが、図１５に示すように、液晶フィルタ３７と、レンズ３８と、プリズム型ローパスフィルタ９６と、２つの光学的バンドパスフィルタ９７、９８と、短波長側撮像素子４６と、長波長側撮像素子４８とによって波長選択光学系３１ｃを構成し、この波長選択光学系３１ｃを使用して、被写体からの光像を波長弁別し、短波長側映像信号と、長波長側映像信号とを生成するようにしても良い。
【００９２】
この場合、プリズム型ローパスフィルタ９６は、プリズム１００と、プリズム１０５と、光学的ローパスフィルタ１０６とを備えている。プリズム１００は、前面９９側が４５度にカットされたプリズムである。プリズム１０５は、前面１０１（後面１０２）と斜面１０３、１０４とのなす角度が４５度、１３５度になるようにカットされた並行四辺形型のプリズムである。光学的ローパスフィルタ９６は、プリズム１０５の斜面１０４とプリズム１００の前面９９との接合面に配置され、図１４に示す光学的ローパスフィルタ９１と同じローパス特性で、入射した光像のうち、長波長領域に属する光像を透過させるとともに、短波長領域に属する光像を反射させる。そして、このプリズム型ローパスフィルタ９６では、レンズ３８から短波長域の光像、長波長域の光像が入射面１０７に入射したとき、光学的ローパスフィルタ１０６のフィルタリング動作によって、長波長領域に属する光像を透過させて、これを出射面１０８から出射させ、光学的バンドパスフィルタ９８に入射させるとともに、光学的ローパスフィルタ１０６によって、短波長側の光像を反射させた後、これを全反射面１０９で反射させて、出射面１１０から出射させ、光学的バンドパスフィルタ９７に入射させる。
【００９３】
光学的バンドパスフィルタ９７は、図１６に示すように、光学的ローパスフィルタ１０６のローパスフィルタリング特性によって選択された短波長側の光像中から波長λ_ｄを中心として、所定領域に含まれる波長の光を抽出するバンドパス特性を持つフィルタ板によって構成されており、プリズム型ローパスフィルタ９６の出射面１１０から出射される短波長側の光像のうち、図１６に示すように、波長λ_ｄを中心とする所定波長領域の光像を選択して、これを短波長側撮像素子４６に入射させ、短波長側映像信号を生成させる。
【００９４】
また、光学的バンドパスフィルタ９８は、図１７に示すように、光学的ローパスフィルタ１０６のローパスフィルタリング特性によって選択された長波長域の光像中から波長λ_ｃを中心として、所定領域に含まれる波長の光を抽出するバンドパス特性を持つフィルタ板によって構成されており、プリズム型ローパスフィルタ９６の出射面１０８から出射される長波長側の光像、長波長側の光像のうち、図１７に示すように、波長λ_ｃを中心とする所定波長領域の光像を選択して、これを長波長側撮像素子４８に入射させ、長波長側映像信号を生成させる。
【００９５】
このように、液晶フィルタ３７と、レンズ３８と、プリズム型ローパスフィルタ９６と、２つの光学的バンドパスフィルタ９７、９８と、短波長側撮像素子４６と、長波長側撮像素子４８とによって波長選択光学系３１ｃを構成し、この波長選択光学系３１ｃを使用しても、被写体からの光像を波長弁別し、短波長側映像信号と、長波長側映像信号とを生成することができる。
【００９６】
＜第２の実施の形態の第４変形例＞
また、図８に示す波長選択型液晶カメラ装置３０では、液晶フィルタ３７と、レンズ３８と、ビームスプリッタ４４と、２つの光学的バンドパスフィルタ４５、４７と、短波長側撮像素子４６と、長波長側撮像素子４８とによって構成される波長選択光学系３１を使用するようにしているが、この波長選択光学系３１を構成している２つの光学的バンドパスフィルタ４５、４７を取り除いた波長選択光学系を使用しても良い。
【００９７】
また、図８に示す波長選択型液晶カメラ装置３０では、液晶フィルタ３７と、レンズ３８と、ビームスプリッタ４４と、２つの光学的バンドパスフィルタ４５、４７と、短波長側撮像素子４６と、長波長側撮像素子４８とによって構成される波長選択光学系３１を使用するようにしているが、この波長選択光学系３１を構成しているビームスプリッタ４４に代えて、図１４に示すプリズム型ローパスフィルタ８１を設けるとともに、２つの光学的バンドパスフィルタ４５、４７を取り除いた波長選択光学系を使用しても良い。
【００９８】
＜第２の実施の形態の第５変形例＞
また、図８に示す波長選択型液晶カメラ装置３０では、交流電圧を印加していないとき、液晶の常光屈折率だけを感じる光線を選択し、また交流電圧を印加しているとき、常光屈折率と異常光屈折率との両方に感じる光線を選択して、各光線を短波長側撮像素子４６、長波長側撮像素子４８に入射させるようにしているが、液晶フィルタ３７の前、後ろ、レンズ３８の後ろに、または短波長側撮像素子４６、長波長側撮像素子４８の前に、偏光フィルム（あるいは、偏光板）を配置し、この偏光フィルムによって、常光屈折率だけを感じる光線を取り除いて、短波長側撮像素子４６、長波長側撮像素子４８に入射させるようにしても良い。
【００９９】
このようにしても、図８に示す波長選択型液晶カメラ装置３０と同様に、従来、検出が困難であった水面上の油膜や有機膜などを高いコントラストで画像として検出することができる。
【０１００】
＜第２の実施の形態の第６変形例＞
また、図８に示す波長選択型液晶カメラ装置３０では、波長選択型光学系３１と、短波長側画像処理部３２と、短波長側差画像抽出部３３と、長波長側画像処理部３４と、長波長側差画像抽出部３５と、映像合成部３６とを１つの筐体内に入れてカメラ装置を構成するようにしているが、映像合成部３６の全てと、短波長側差画像抽出部３３の全てと、長波長側差画像抽出部３５の全てと、短波長側画像処理部３２の全てまたは一部と、長波長側画像処理部３４の全てまたは一部とをカメラ装置から分離するようにしても良い。
【０１０１】
このようにすることにより、カメラ装置部分を小型、軽量化して、カメラ装置の取扱いや操作などを容易にすることができる。
【０１０２】
《発明の第３の実施の形態の説明》
＜第３の実施の形態の基本説明＞
図１８は本発明による波長選択型液晶カメラ装置の第３の実施の形態を示すブロック図である。なお、この図においては、説明を簡単にするために、本発明の説明に係わりのない部分、例えば入射光量を減衰させるアイリスやＮＤフィルタなど、カメラ装置を構成するのに必要な部品、駆動回路、映像処理回路などにパルス信号を送るパルス発生回路、映像の輪郭を強調する輪郭補償回路、電源回路などを省略してある。
【０１０３】
この図に示す波長選択型液晶カメラ装置１１１は、フルカラー波長選択光学系１１２と、Ｒ色画像処理部１１３と、Ｒ色差画像抽出部１１４とを備えている。フルカラー波長選択光学系１１２は、被写体からの光像を取り込んで、Ｒ、Ｇ、Ｂの三原色に分離するとともに、Ｒ、Ｇ、Ｂ毎に、短波長域の光像、長波長域の光像を抽出して、光電変換し、Ｒ光像に対する短波長域の映像信号（Ｒ色短波長域映像信号）、長波長域の映像信号（Ｒ色長波長域映像信号）、Ｇ光像に対する短波長域の映像信号（Ｇ色短波長域映像信号）、長波長域の映像信号（Ｇ色長波長域映像信号）、Ｂ光像に対する短波長域の映像信号（Ｂ色短波長域映像信号）、長波長域の映像信号（Ｂ色長波長域映像信号）を順次生成する。Ｒ色画像処理部１１３は、このフルカラー波長選択光学系１１２から順次出力されるＲ色短波長域映像信号、Ｒ色長波長域映像信号を画像処理してデジタル化したＲ色短波長域映像信号、Ｒ色長波長域映像信号を順次生成する。Ｒ色差画像抽出部１１４は、Ｒ色画像処理部１１３から出力されるＲ色短波長域映像信号、Ｒ色長波長域映像信号の少なくともいずれか一方をフレーム単位で記憶しながら、これらＲ色短波長域映像信号とＲ色長波長域映像信号との差に基づき、海面や水面などに浮かんだ油膜の映像や有機膜の映像などのコントラストを高くしたＲ色映像信号を生成する。
【０１０４】
さらに、波長選択型液晶カメラ装置１１１は、Ｇ色画像処理部１１５と、Ｇ色差画像抽出部１１６と、Ｂ色画像処理部１１７と、Ｂ色差画像抽出部１１８と、エンコーダ回路１１９とを備えている。Ｇ色画像処理部１１５は、フルカラー波長選択光学系１１２から順次出力されるＧ色短波長域映像信号、Ｇ色長波長域映像信号を画像処理してデジタル化したＧ色短波長域映像信号、Ｇ色長波長域映像信号を順次生成する。Ｇ色差画像抽出部１１６は、Ｇ色画像処理部１１５から出力されるＧ色短波長域映像信号、Ｇ色長波長域映像信号の少なくともいずれか一方をフレーム単位で記憶しながら、これらＧ色短波長域映像信号とＧ色長波長域映像信号との差に基づき、海面や水面などに浮かんだ油膜の映像や有機膜の映像などのコントラストを高くしたＧ色映像信号を生成する。Ｂ色画像処理部１１７は、フルカラー波長選択光学系１１２から順次出力されるＢ色短波長域映像信号、Ｂ色長波長域映像信号を画像処理してデジタル化したＢ色短波長域映像信号、Ｂ色長波長域映像信号を順次生成する。Ｂ色差画像抽出部１１８は、Ｂ色画像処理部１１７から出力されるＢ色短波長域映像信号、Ｂ色長波長域映像信号の少なくともいずれか一方をフレーム単位で記憶しながら、これらＢ色短波長域映像信号とＢ色長波長域映像信号との差に基づき、海面や水面などに浮かんだ油膜の映像や有機膜の映像などのコントラストを高くしたＢ色映像信号を生成する。エンコーダ回路１１９は、Ｒ色差画像抽出部１１４、Ｇ色差画像抽出部１１６、Ｂ色差画像抽出部１１８からそれぞれ出力されるＲ色映像信号、Ｇ色映像信号、Ｂ色映像信号を合成して、合成カラーテレビ信号を生成する。
【０１０５】
フルカラー波長選択光学系１１２は、図１、図８に示す液晶フィルタ５、３７と同様に、液晶フィルタ１２０と、レンズ１２１と、ダイクロイックプリズム１２３と、Ｒ色撮像素子１２４と、Ｇ色撮像素子１２５と、Ｂ色撮像素子１２６とを備えており、被写体からの光像（白色の光像）を取り込むとともに、入力される交流電圧に応じて、光像を構成する短波長域の光像と、光像を構成する長波長域の光像とを順次サイクリックに抽出しながら、これら短波長域の光像と、長波長域の光像とをＲ色の光像、Ｇ色の光像、Ｂ色の光像とに分離した後、これらＲ色の光像、Ｇ色の光像、Ｂ色の光像をそれぞれ光電変換し、これによって得られたＲ色短波長域映像信号と、Ｒ色長波長域映像信号とをＲ色画像処理部１１３に順次供給し、またＧ色短波長域映像信号と、Ｇ色長波長域映像信号とをＧ色画像処理部１１５に順次供給し、さらにＢ色短波長域映像信号と、Ｂ色長波長域映像信号とをＢ色画像処理部１１７に順次供給する。液晶フィルタ１２０は、被写体からの光像（白色の光像）を取り込むとともに、入力される交流電圧に応じて、短波長域の光像、長波長域の光像を抽出する。レンズ１２１は、この液晶フィルタ１２０によって抽出された短波長域の光像、長波長域の光像を集光させて、所定距離だけ後方に結像させる。ダイクロイックプリズム１２３は、レンズ１２１によって集光されている短波長域の光像、長波長域の光像をＲ色の光像とＧ色の光像とＢ色の光像とに分離する。Ｒ色撮像素子１２４は、ＣＣＤ、ＭＯＳ、ＣＰＤ、ＳＩＴ、ＡＭＩなど、シリコンを用いた固体撮像素子またはＧａＡｓ、ＩｎＧａＡｓなど赤外線領域で高い感度を示す材料を用いた固体撮像素子、または非晶質セレンなど、紫外線や短波長可視光で高い感度を示す材料を用いた固体撮像素子、あるいはプランビコン、サチコン、ビジコン、カルニコン、ハーピコンなどの撮像管のいずれかによって構成され、ダイクロイックプリズム１２３から出射されるＲ色の短波長域の光像、長波長域の光像を光／電変換し、Ｒ色短波長域映像信号、Ｒ色長波長域映像信号を順次サイクリックに生成する。Ｇ色撮像素子１２５は、Ｒ色撮像素子１２４と同様に構成され、ダイクロイックプリズム１２３から出射されるＧ色の短波長域の光像、長波長域の光像を光／電変換し、Ｇ色短波長域映像信号、Ｇ色長波長域映像信号を順次サイクリックに生成する。Ｂ色撮像素子１２６は、Ｒ色撮像素子１２４、Ｇ色撮像素子１２５と同様に構成され、ダイクロイックプリズム１２３から出射されるＢ色の短波長域の光像、長波長域の光像を光／電変換し、Ｂ色短波長域映像信号、Ｂ色長波長域映像信号を順次サイクリックに生成する。
【０１０６】
Ｒ色画像処理部１１３は、図１９に示すように、ヘッドアンプ回路１２７と、映像処理回路１２８と、Ａ／Ｄ変換回路１２９とを備えており、フルカラー波長選択光学系１１２から出力されるＲ色短波長域映像信号、Ｒ色長波長域映像信号に対し、前置増幅処理、液晶フィルタ１２０の透過領域補償処理、液晶フィルタ１２０の透過率補償処理などを行い、これによって得られたＲ色短波長域映像信号、Ｒ色長波長域映像信号をデジタル化して、Ｒ色差画像抽出部１１４に供給する。ヘッドアンプ回路１２７は、フルカラー波長選択光学系１１２から順次出力されるＲ色短波長域映像信号、Ｒ色長波長域映像信号を一定の増幅率で増幅する。映像処理回路１２８は、ヘッドアンプ回路１２７から順次出力されるＲ色短波長域映像信号、Ｒ色長波長域映像信号に対し、予め設定されている画像処理、例えば液晶フィルタ１２０の透過領域補償、液晶フィルタ１２０の透過率補償などを行う。Ａ／Ｄ変換回路１２９は、この映像処理回路１２８から順次出力されるＲ色短波長域映像信号、Ｒ色長波長域映像信号をＡ／Ｄ変換して、デジタル化されたＲ色短波長域映像信号、Ｒ色長波長域映像信号を生成する。
【０１０７】
Ｒ色差画像抽出部１１４は、フレームメモリ回路１３０と、差分回路１３１と、絶対値回路１３２と、Ｄ／Ａ変換回路１３３と、増幅回路１３４とを備え、入力されている垂直同期信号に基づき、Ｒ色画像処理部１１３からデジタル化されたＲ色短波長域映像信号が出力されたとき、これを取り込んで記憶するとともに、Ｒ色画像処理部１１３からデジタル化されたＲ色長波長域映像信号が出力されたとき、このＲ色長波長域映像信号と、記憶しているＲ色短波長域映像信号とを画素単位で比較して、同じ空間座標の各画素同士のレベル差を演算し、これによって得られたＲ色短波長域映像信号とＲ色長波長域映像信号との差を示すＲ色映像信号（例えば、水面に浮かんだ油膜の映像や有機膜の映像などのコントラストを高くしたＲ色映像信号）をアナログ化して、エンコーダ回路１１９に供給する。フレームメモリ回路１３０は、入力されている垂直同期信号に基づき、Ｒ色画像処理部１１３から出力されるデジタル化されたＲ色短波長域映像信号、Ｒ色長波長域映像信号のうち、予め設定されている波長領域の映像信号、例えばＲ色短波長域映像信号をフレーム単位で取り込んで、記憶した後、Ｒ色画像処理部１１３からＲ色長波長域映像信号が出力されたとき、これに同期して、記憶しているＲ色短波長域映像信号を出力する。差分回路１３１は、入力されている垂直同期信号に基づき、フレームメモリ回路１３０から出力されるＲ色短波長域映像信号とＲ色画像処理部１１３から出力されるＲ色長波長域映像信号とを画素単位で比較し、同じ空間座標の各画素同士のレベル差を演算してＲ色短波長域映像信号とＲ色長波長域映像信号との差を示すＲ色映像信号を生成する。対値回路１３２は、差分回路１３１から出力されるＲ色映像信号の絶対値を演算する。Ｄ／Ａ変換回路１３３は、この絶対値回路１３２から出力されるデジタル信号形式のＲ色映像信号をアナログ信号形式のＲ色映像信号に変換する。増幅回路１３４は、Ｄ／Ａ変換回路１３３から出力されるＲ色映像信号を増幅する。
【０１０８】
また、Ｇ色画像処理部１１５は、Ｒ色画像処理部１１５と同様、図２０に示すように、ヘッドアンプ回路１２７と、映像処理回路１２８と、Ａ／Ｄ変換回路１２９とを備えており、フルカラー波長選択光学系１１２から出力されるＧ色短波長域映像信号、Ｇ色長波長域映像信号に対し、前置増幅処理、液晶フィルタ１２０の透過領域補償処理、液晶フィルタ１２０の透過率補償処理などを行い、これによって得られたＧ色短波長域映像信号、Ｇ色長波長域映像信号をデジタル化して、Ｇ色差画像抽出部１１６に供給する。
【０１０９】
Ｇ色差画像抽出部１１６は、Ｒ色差画像抽出部１１４と同様、フレームメモリ回路１３０と、差分回路１３１と、絶対値回路１３２と、Ｄ／Ａ変換回路１３３と、増幅回路１３４とを備えており、入力されている垂直同期信号に基づき、Ｇ色画像処理部１１５からデジタル化されたＧ色短波長域映像信号が出力されたとき、これを取り込んで記憶するとともに、Ｇ色画像処理部１１５からデジタル化されたＧ色長波長域映像信号が出力されたとき、このＧ色長波長域映像信号と、記憶しているＧ色短波長域映像信号とを画素単位で比較して、同じ空間座標の各画素同士のレベル差を演算し、これによって得られたＧ色短波長域映像信号とＧ色長波長域映像信号との差を示すＧ色映像信号（例えば、水面に浮かんだ油膜の映像や有機膜の映像などのコントラストを高くしたＧ色映像信号）をアナログ化して、エンコーダ回路１１９に供給する。
【０１１０】
また、Ｂ色画像処理部１１７も前記Ｒ色画像処理部１１３、Ｇ色画像処理部１１５と同様、図２１に示すように、ヘッドアンプ回路１４３と、映像処理回路１４４と、Ａ／Ｄ変換回路１４５とを備えており、フルカラー波長選択光学系１１２から出力されるＢ色短波長域映像信号、Ｂ色長波長域映像信号に対し、前置増幅処理、液晶フィルタ１２０の透過領域補償処理、液晶フィルタ１２０の透過率補償処理などを行い、これによって得られたＢ色短波長域映像信号、Ｂ色長波長域映像信号をデジタル化して、Ｂ色差画像抽出部１１８に供給する。
【０１１１】
Ｂ色差画像抽出部１１８は、前記Ｒ色差画像抽出部１１４、Ｇ色差画像抽出部１１６と同様、フレームメモリ回路１４６と、差分回路１４７と、絶対値回路１４８と、Ｄ／Ａ変換回路１４９と、増幅回路１５０とを備えており、入力されている垂直同期信号に基づき、Ｂ色画像処理部１１７からデジタル化されたＢ色短波長域映像信号が出力されたとき、これを取り込んで記憶するとともに、Ｂ色画像処理部１１７からデジタル化されたＢ色長波長域映像信号が出力されたとき、このＢ色長波長域映像信号と、記憶しているＢ色短波長域映像信号とを画素単位で比較して、同じ空間座標の各画素同士のレベル差を演算し、これによって得られたＢ色短波長域映像信号とＢ色長波長域映像信号との差を示すＢ色映像信号（例えば、水面に浮かんだ油膜の映像や有機膜の映像などのコントラストを高くしたＢ色映像信号）をアナログ化して、エンコーダ回路１１９に供給する。
【０１１２】
エンコーダ回路１１９は、Ｒ色差画像抽出部１１４から出力されるＲ色映像信号と、Ｇ色差画像抽出部１１６から出力されるＧ色映像信号と、Ｂ色差画像抽出部１１８から出力されるＢ色映像信号を取り込んで、これを予め設定されている合成方法で、合成して、合成カラーテレビ信号を生成し、これをディスプレイ装置などに供給し、油膜像などを画像化する。
【０１１３】
このように、この実施の形態では、フルカラー波長選択光学系１１２によって、油膜が浮かんだ海面などを撮影して、Ｒ、Ｇ、Ｂ毎に、短波長域の映像信号と、長波長域の映像信号とを順次生成しながら、Ｒ色画像処理部１１３、Ｇ色画像処理部１１５、Ｂ色画像処理部１１７によってＲ、Ｇ、Ｂ毎に、短波長域の映像信号と、長波長域の映像信号とを画像処理して、デジタル化した短波長域の映像信号と、長波長域の映像信号とを生成した後、Ｒ色差画像抽出部１１４、Ｇ色差画像抽出部１１６、Ｂ色差画像抽出部１１８によってＲ、Ｇ、Ｂ毎に、短波長域の映像信号と、長波長域の映像信号との差を抽出して、水面などに浮かんだ油膜の映像や有機膜の映像などのコントラストを高くしたＲ、Ｇ、Ｂ毎の映像信号を生成し、これを合成して得られた合成カラーテレビ信号をディスプレイ装置に供給するようにしているので、水面の状態がどのような状態であっても、水面上の油膜や有機膜などを高いコントラストでフルカラー画像として検出することができる。
【０１１４】
これによって、従来、ヘリコプタや航空機などから目視観察で遭難現場などを探索しても、油膜の発見が困難な場合、例えば海面からの反射光が強い場合（逆光状態）、雨天の場合、波浪が高い場合などでも、海面の状態に関わらず、遭難した航空機や船舶などの油膜が海面上に浮いているとき、これを確実に検出して、遭難現場などを見つけ出すことができる。
【０１１５】
また、この実施の形態では、撮影した海面などに油膜や有機膜などがあるときにのみ、Ｒ色差画像抽出部１１４、Ｇ色差画像抽出部１１６、Ｂ色差画像抽出部１１８から出力されるＲ色映像信号、Ｇ色映像信号、Ｂ色映像信号がゼロ以外の値になるようにしているので、エンコーダ回路１１９から出力される合成カラーテレビ信号を判定回路（図示は省略する）に導き、予め設定されているしきい値を越えているかどうかを判定させるだけで、遭難現場の探索を容易に自動化することができる。これによって、ヘリコプタや航空機などに、図１８に示す波長選択型液晶カメラ装置１１１を複数搭載し、各波長選択型液晶カメラ装置１１１によって、全方位を同時に探索させ、油膜などの有無を自動判定させれば、従来の目視による場合に比べて、格段に探索効率を向上させて、迅速な災害救助を行うことができる。
【０１１６】
また、図１８に示す波長選択型液晶カメラ装置１１１と、ＧＰＳ（Global Positioning System）装置とを組み合わせることにより、油膜の位置を瞬時に決定することができ、これによって遭難現場などの発見を一層、迅速化させることができるとともに、タンカーなどの原油流出状況をリアルタイムで、容易に地図化することができる。
【０１１７】
＜第３の実施の形態の第１変形例＞
また、図１８に示す波長選択型液晶カメラ装置１１１では、液晶フィルタ１２０によって被写体からの光像に含まれている短波長域の光像と、長波長域の光像とを交互に抽出し、ダイクロイックプリズム１２３によって、短波長域の光像と、長波長域の光像とをＲ色、Ｇ色、Ｂ色に分離して、Ｒ撮像素子１２４上、Ｇ撮像素子上１２５、Ｂ撮像素子１２６上にそれぞれ結像させるようにしているが、図２２に示すフルカラー波長選択光学系１１２ａのように、ダイクロイックプリズム１２３の前に、光学的バンドパスフィルタ１５１を配置し、この光学的バンドパスフィルタ１５１によって、液晶フィルタ１２０で選択された短波長域の光像と、長波長域の光像とをバンドパスフィルタリングして、波長範囲を絞り込んだ後、ダイクロイックプリズム１２３によって、Ｒ色、Ｇ色、Ｂ色に分離し、Ｒ色撮像素子１２４上、Ｇ色撮像素子１２５上、Ｂ色撮像素子１２６上にそれぞれ結像するようにしても良い。
【０１１８】
但し、この光学的バンドパスフィルタ１５１の半値全幅（Full width Half Maximum）をＲ色撮像素子１２４、Ｇ色撮像素子１２５、Ｂ色撮像素子１２６に入射する光像の半値全幅より広くすることが必要である。
【０１１９】
このようにしても、図１８に示す波長選択型液晶カメラ装置１１１と同様に、従来、検出が困難であった水面上の油膜や有機膜などを高いコントラストのフルカラー画像として検出することができる。
【０１２０】
また、この第１変形例では、ダイクロイックプリズム１２３の前に、光学的バンドパスフィルタ１５１を配置するようにしているが、Ｒ撮像素子１２４、Ｇ撮像素子１２５、Ｂ撮像素子１２６の前であれば、液晶フィルタ１２０の前に１つの光学的バンドパスフィルタを配置しても、またダイクロイックプリズム１２３の後に３つの光学的バンドパスフィルタを配置しても良い。
【０１２１】
このように、Ｒ撮像素子１２４、Ｇ撮像素子１２５、Ｂ撮像素子１２６の前であれば、どこに光学的バンドパスフィルタを配置しても、この第１変形例と同じ効果を得ることができる。
【０１２２】
＜第３の実施の形態の第２変形例＞
また、図１８に示す波長選択型液晶カメラ装置１１１では、液晶の常光屈折率だけを感じる光線と、電圧が印加されて、常光屈折率と異常光屈折率との両方に感じる光線とをＲ撮像素子１２４、Ｇ撮像素子１２５、Ｂ撮像素子１２６に入射させるようにしているが、図２３に示すフルカラー波長選択光学系１１２ｂのように、液晶フィルタ１２０の後ろに、偏光フィルム（あるいは、偏光板）１５２を配置し、この偏光フィルム１５２によって、常光屈折率だけを感じる光線を取り除いて、Ｒ撮像素子１２４、Ｇ撮像素子１２５、Ｂ撮像素子１２６に入射させるようにしても良い。
【０１２３】
このようにしても、図１８示す波長選択型液晶カメラ装置１１１と同様に、従来、検出が困難であった水面上の油膜や有機膜などを高いコントラストのフルカラー画像として検出することができる。
【０１２４】
また、この第２変形例では、液晶フィルタ１２０と、レンズ１２１との間に、偏光フィルム１５２を配置するようにしているが、Ｒ撮像素子１２４、Ｇ撮像素子１２５、Ｂ撮像素子１２６の前であれば、液晶フィルタ１２０の前、またはレンズ１２１の後ろ、あるいはダイクロイックプリズム１２３の各出射面などに偏光フィルムを配置しても良い。
【０１２５】
＜第３の実施の形態の第３変形例＞
また、図１８に示す波長選択型液晶カメラ装置１１１では、フルカラー波長選択型光学系１１２と、Ｒ色画像処理部１１３と、Ｒ色差画像抽出部１１４と、Ｇ色画像処理部１１５と、Ｇ色差画像抽出部１１６と、Ｂ色画像処理部１１７と、Ｂ色差画像抽出部１１８と、エンコーダ回路１１９とを１つの筐体内に入れてカメラ装置を構成するようにしているが、エンコーダ回路１１９の全てと、Ｒ色差画像抽出部１１４の全てと、Ｇ色差画像抽出部１１６の全てと、Ｂ色差画像抽出部１１８の全てと、Ｒ色画像処理部１１３の全てまたは一部と、Ｇ色画像処理部１１５の全てまたは一部と、Ｂ色画像処理部１１７の全てまたは一部とをカメラ装置から分離するようにしても良い。
【０１２６】
このようにすることにより、カメラ装置部分を小型、軽量化して、カメラ装置の取扱いや操作などを容易にすることができる。
【０１２７】
《第１〜第３の実施の形態で使用される液晶の説明》
また、上述した第１〜第３の実施の形態では、液晶フィルタ５、３７、１２０として、強誘電性液晶や反強誘電性液晶など、交流電圧の有無に応じて、一方の透過特性から他方の透過特性に素早く切り替えることができる、応答速度が優れた液晶フィルタを用いる場合、何に問題が発生しない。
【０１２８】
さらに、液晶フィルタ５、３７、１２０として、ネマチック液晶やコレステリック液晶など、交流電圧の有無に応じて、一方の透過特性から他方の透過特性に素早く切り替えることができない、応答速度が遅い液晶フィルタを用いた場合には、トランジェントな動作を考慮しなければならないことから、このような特性を持つ液晶をディスプレイ装置などに使用するときには、大きな問題になるが、本発明よる波長選択型液晶カメラ装置１、３０、１１１では、殆ど問題にならない。以下、この理由について、詳細に説明する。
【０１２９】
まず、各液晶フィルタ５、３７、１２０、例えば液晶フィルタ５を構成している各誘電体多層膜１０、１３のパワー反射率を“Ｒ”とし、液晶層１４に垂直に入射した光が液晶層１４内を１回だけ通過するときの位相変化量を“δ”とし、さらに入射光が直線偏光しているものと仮定すると、液晶層１４、各誘電体多層膜１０、１３など、液晶フィルタ５を構成している各層の光吸収率を無視したとき、液晶フィルタ５の透過率Ｔは、次式で表わすことができる。
【０１３０】
［数７］
Ｔ＝［１＋４Ｒｓｉｎ^２（δ／２）／（１−Ｒ）^２］^−１ …（７）
そして、真空中における光の波長を“λ”とし、液晶層１４を構成している液晶の屈折率を“ｎ”、厚さを“Ｄ”とすると、位相変化量δは、次式で表わすこととができる。
【０１３１】
δ＝４πｎＤ／λ …（８）
【０１３２】
ここで、“Ｒ＝０．７”として、（７）式、（８）式から透過率Ｔと、波長λとの関係を計算すると、図２４に示すグラフが得られ、このグラフから明らかなように、液晶層１４を構成している液晶の屈折率ｎが変化しても、中心波長（液晶フィルタ５の透過率Ｔが最大となる波長）がずれるだけで、透過率のカーブが変化しない。
【０１３３】
これにより、液晶の応答が遅い場合、波長フィルタ５が様々な波長を選択しながら、ある波長に落ち着くように動作し、このとき表１に示すように、水の屈折率が波長依存性を持つものの、液晶によって生じる程度の波長変化では、淡水や海水の屈折率が殆ど変化しないことから、液晶フィルタ５がトランジェントな動作をしても、海面上に油膜が無ければ、水面の明るさが一定になって、２つのフレーム間に信号のレベル差が無くなり、ディスプレイ装置上にゼロを示す画像が表示される。
【０１３４】
これに対し、図５に示すように、海面上に油膜がある場合には、波長が僅かに変化しても、油膜の反射光強度が大きく変化することから、液晶フィルタ５がトランジェントな動作をしても、２つのフレーム間に信号のレベル差が現われて、
ディスプレイ装置上に油膜の画像が表示される。
【０１３５】
ただし、トランジェントな特性を考慮すると、液晶フィルタ５を透過した２つの光量（太い実線の合計値と、細い実線の合計値）が常に一致するとは限らないことから、予め白紙など反射率が一定の物を撮影して、２つの異なる波長に対する光電変信号が一致するように、画像処理部３を構成している映像処理回路１６の透過率特性、反射率特性などを調整（セットアップ調整）しておく必要がある。
【０１３６】
また、強誘電性液晶なども、厳密に言えば、僅かなトランジェント効果が現われることから、ネマチック液晶と同様に、白紙などを撮影して、セットアップ調整を行っておく方が良い。
【０１３７】
また、稀なケースではあるが、油膜がある海面を撮影したとき、特定の入射角度からの光が入射されて、液晶フィルタ５から出力される短波長域の光像の光量と、長波長域の光像の光量とが一致することも考えられるが、このような特殊な場合でも、波長選択型液晶カメラ装置１は、様々な入射角度φ_１からの光像が入射して画像化するため、油膜の存在を見失うことは無い。
【０１３８】
同様に、図２５に示すように、波や風などによって海面１５３が常に変動し、海面１５３が鏡面状態のときの入射角度よりも、多様な入射角度からの光像がヘリコプタ１５４に搭載された波長選択型液晶カメラ装置１に取り込まれることから、特定の入射角度で反射率が同じレベルになっても、他の入射角度で反射率が異なるレベルになり、油膜を見失うことが殆ど無い。
【０１３９】
特に、図８に示す波長選択型液晶カメラ装置３０などのように、短波長側の光像と、長波長側の光像とに分けている場合、あるいは図１８に示す波長選択型液晶カメラ装置１１１などのように、Ｒ色の光像、Ｇ色の光像、Ｂ色の映像信号に分けている場合などのように、波長が異なる複数の映像信号を作成している場合には、いずれかの波長領域で、油膜や有機膜を検出することができることから、油膜や有機膜などを確実に検出して、油膜などを見失わないようにすることができる。
【０１４０】
《第１〜第３の実施の形態における油膜検出感度の説明》
次に、上述した各波長選択型液晶カメラ装置１、３０、１１１を使用して、海面上に浮いている油膜を検出する際における撮像素子７、短波長側撮像素子４６、長波長側撮像素子４８、Ｒ色撮像素子１２４、Ｇ色撮像素子１２５、Ｂ色撮像素子１２６などの分解能と、油膜検出感度の関係について説明する。
【０１４１】
＜静止状態での探査能力＞
まず、上述した各波長選択型液晶カメラ装置１、３０、１１１、例えば図１に示す波長選択型液晶カメラ装置１で使用されている撮像素子７の最小検出単位である各画素（ピクセル）が大きい場合や撮影距離が短い場合には、１つのピクセルに対し、入射角度φ_１が異なる複数の光線が入射し、各ピクセルの出力が各光線の輝度を加算した値になる。
【０１４２】
この際、各光線毎の入射角度φ_１が異なり、その角度差が大きいと、反射率から求めた輝度の波長依存性が緩和されて、油膜検出感度が低下する恐れがあることから、この点について詳細に説明する。
【０１４３】
今、波長選択型液晶カメラ装置１で使用される撮像素子７として、垂直画素数が“４５０”、水平画素数が“６００”程度の画素数に設定され、かつピクセルの受光部が正方形に形成される撮像素子を使用するものと仮定し、図２６に示すように、ヘリコプタ１５５に波長選択型液晶カメラ装置１を取り付けて、波長選択型液晶カメラ装置１の画像取込み角度（波長選択型液晶カメラ装置１の光軸１５６と被写体からの光線１５７、１５８とがなす最大角度）を所定の値、例えば“±２５度”になるようにレンズ６を調整するとともに、波長選択型液晶カメラ装置１の光軸１５６が海面１５９と直交するように、波長選択型液晶カメラ装置１の撮影方向を調整した状態で、海面１５９からの高さが３００〜１０００ｍとなるようにヘリコプタ１５５を飛ばして、海面１５９上に浮かんでいる油膜を探査する場合を考える。
【０１４４】
この場合、ヘリコプタ１５５が、例えば海面１５９から３００〜１０００ｍ上空、例えば８００ｍ上空を飛びながら、波長選択型液晶カメラ装置１によって海面１５９を撮影すると、図２７に示すように波長選択型液晶カメラ装置１の撮像素子７の撮影動作によって、１フレーム間に、海面１５９上で、直径“７４６ｍ”の円に内接する長方形の領域ＡＢＣＤ（約５９７ｍ×約４４８ｍ）を探査することができることから、海面１５９上の“約１ｍ^２”の部分からの光線が撮像素子７を構成する１つのピクセルに入射される。
【０１４５】
この面積は、波やうねりなどによる海面１５９の揺らぎと比較すると、十分に小さな値であることから、本発明による波長選択型液晶カメラ装置１を使用するだけで、従来から使用されている通常の探索方法でも、十分な検出感度で、海面１５９に浮いている油膜を検出することができる。また、ハイビジョンテレビカメラ装置などの高解像度テレビカメラ装置で使用されている撮像素子を用いれば、分解できる最小面積Ｓを“０．２ｍ^２”にすることができることから、探査能力をさらに向上させることができる。
【０１４６】
＜移動状態での探査能力、探査範囲＞
また、探査範囲を広げるために、ヘリコプタ１５５を移動させながら、海面１５９上に浮いている油膜を探査する場合には、上述した分解可能な最小面積Ｓまで、検出するには、ヘリコプタ１５５の飛行速度Ｖ（ｋｍ／ｈ）を以下に示す値にすることが望ましい。
【０１４７】
［数８］
Ｓ^０．５≦（Ｖ×１０^３）／（３．６×１０^３×３０） …（９）
このように、ヘリコプタ１５５の飛行速度Ｖ（ｋｍ／ｈ）を規制しても、ヘリコプタ１５５の飛行速度Ｖが約１０８ｋｍ／ｈのとき、撮像素子７を構成する１ピクセル当たりの探査面積ＳをＳ≒１ｍ^２にすることができ、これによって油膜検出時における十分な分解能を確保しながら、１時間当たり、“６４．８ｋｍ^２（１０８×０．６ｋｍ^２）”の広い範囲を探索することができる。
【０１４８】
＜高速移動状態での探査能力、探査範囲＞
また、このように、移動しながら探査する方法では、撮影方法として、連続撮影方法を使用することから、隣接したテレビフレーム間では、上下２画素列しか画像が変化しないようにすることができ、目視で映像信号の画像を観察して油膜などを検出する際には、これで十分であるが、本発明による波長選択型液晶カメラ装置１では、次段装置内に判定回路を設けることにより、ＣＣＤなどの撮像素子７が持つ垂直画素数に匹敵する距離毎に撮影を行うようにすれば、探査を行うヘリコプタ１５５などの飛行速度をさらに速くすることができ、これによってさらに広い範囲を捜索することができる。
【０１４９】
但し、このような方法で、撮影を行う場合には、撮像素子７の前に光シャッタを設け、この光シャッタを動作させて、各ピクセルに空間分解能以下の海面面積からの光を入れることが必要であることから、光シャッタの開口時間ｔと、探査を行うヘリコプタ１５５などの飛行速度Ｖ（ｋｍ／ｈ）とが次式を満たすようにすることが望ましい。
【０１５０】
［数９］
Ｓ^０．５≦（Ｖ×１０^３×ｔ）／（３．６×１０^３） …（１０）
これにより、ヘリコプタ１５５に搭載した波長選択型液晶カメラ装置１に設けた光シャッタの開口時間ｔを“ｔ＝５（ミリ秒）”にしたとき、“Ｖ≦７２０（ｋｍ／ｈ）”にすることができ、先の例に比べて、およそ６．７倍（７２０×０．６＝４３２ｋｍ^２）に拡大することができる。
【０１５１】
さらに、１台のヘリコプタ１５５や航空機などに、波長選択型液晶カメラ装置１を複数台、搭載し、各波長選択型液晶カメラ装置１の撮影方向を互いに異ならせて、異なる方向を探査すれば、さらに探査範囲を拡大することができる。例えば、３台の波長選択型液晶カメラ装置１を使用して、左右および真下を同時に監視すれば、１時間当たりの探査範囲を約１３００ｋｍ^２にすることができ、これによって１時間以内で、東京湾全域を隈無く探索することができる。
【０１５２】
＜光シャッタの選択＞
また、上述した光シャッタとしては、ネマチック液晶、コレステリック液晶、スメクチック液晶などの材料を使用することができる。この場合、光シャッタとして、９０度ねじれネマチック液晶を使用すれば、白色光を変調することができ、これによって広い波長範囲で利用することができ、またスメクチック液晶の一種である強誘電性液晶や反強誘電性液晶を使用すれば、１ミリ秒以下の高速度で、光画像をピックアップすることができる。
【０１５３】
また、光シャッタとして、ＬｉＮｂＯ_３、ＬｉＴａＯ_３、ＫＤＰ、ＤＫＤＰ、ＰＺＴ、ＧａＡｓなどの電気材料を用いることもできる。但し、各電気材料の特性として、非常に高速で光像の透過／不透過を制御することができるものの、駆動する際、大きな印加電圧が必要である。
【０１５４】
これらのことから、光シャッタとして、強誘電性液晶や反強誘電性液晶を使用することが望ましい。
【０１５５】
【発明の効果】
以上説明したように本発明によれば、海面からの反射光が強い場合でも、海面上などに浮いている油膜や有機膜、または液晶ディスプレイやプラズマディスプレイなどのガラス基板の表面に付着した油膜や有機膜の汚れなどを高いコントラストで映像化することができ、これによって遭難現場やガラス基板の汚れなどを確実に見つけ出すことができる。
【０１５６】
また、海面からの反射光が強い場合でも、また海面がどのような状態であっても、海面上などに浮いている油膜や有機膜、または液晶ディスプレイやプラズマディスプレイなどのガラス基板の表面に付着した油膜や有機膜の汚れなどを高いコントラストで映像化することができ、これによって遭難現場やガラス基板の汚れなどを確実に見つけ出すことができる。
【０１５７】
また、海面からの反射光が強い場合でも、また海面がどのような状態であっても、海面上などに浮いている油膜や有機膜、または液晶ディスプレイやプラズマディスプレイなどのガラス基板の表面に付着した油膜や有機膜の汚れなどを高いコントラストでカラー映像化することができ、これによって遭難現場やガラス基板の汚れなどを確実に見つけ出すことができる。
【０１５８】
また、ヘリコプタや航空機などで、探索範囲の上空を高速で飛行しながら、海面からの反射光が強い場合でも、また海面がどのような状態であっても、海面上などに浮いている油膜や有機膜などを高いコントラストで映像化することができ、これによって遭難現場などを迅速に、かつ確実に見つけ出すことができる。
【図面の簡単な説明】
【図１】 本発明による波長選択型液晶カメラ装置の第１の実施の形態を示すブロック図である。
【図２】 図１に示す液晶フィルタの詳細な構成を示す断面図である。
【図３】 図１に示す液晶フィルタに入力される交流電圧と、各フレームとの関係を示す波形図である。
【図４】 図１に示す画像処理部、差画像抽出部の詳細な回路構成を示すブロック図である。
【図５】 図１に示す波長選択型液晶カメラ装置の波長選択動作例を示すグラフである。
【図６】 図１に示す波長選択型液晶カメラ装置の第１変形例を示すブロック図である。
【図７】 図１に示す波長選択型液晶カメラ装置の第２変形例を示すブロック図である。
【図８】 本発明による波長選択型液晶カメラ装置の第２の実施の形態を示すブロック図である。
【図９】 図１０に示す短波長側画像処理部、短波長側差画像抽出部の詳細な回路構成を示すブロック図である。
【図１０】 図８に示す長波長側画像処理部、長波長側差画像抽出部の詳細な回路構成を示すブロック図である。
【図１１】 図８に示す波長選択型液晶カメラ装置の第１変形例で使用される波長選択光学系を示すブロック図である。
【図１２】 図１１に示す波長選択光学系を構成する光学的ローパスフィルタ、光学的ハイパスフィルタの波長選択特性例を示すグラフである。
【図１３】 図１１に示す波長選択光学系を構成する各光学的ローパスフィルタの波長選択特性例を示すグラフである。
【図１４】 図８に示す波長選択型液晶カメラ装置の第２変形例で使用される波長選択光学系を示すブロック図である。
【図１５】 図８に示す波長選択型液晶カメラ装置の第３変形例で使用される波長選択光学系を示すブロック図である。
【図１６】 図１５に示す波長選択光学系を構成する光学的ローパスフィルタ、一方の光学的バンドパスフィルタの波長選択特性例を示すグラフである。
【図１７】 図１５に示す波長選択光学系を構成する光学的ローパスフィルタ、他方の光学的バンドパスフィルタの波長選択特性例を示すグラフである。
【図１８】 本発明による波長選択型液晶カメラ装置の第３の実施の形態を示すブロック図である。
【図１９】 図１８に示すＲ色画像処理部、Ｒ色差画像抽出部の詳細な回路構成を示すブロック図である。
【図２０】 図１８に示すＧ色画像処理部、Ｇ色差画像抽出部の詳細な回路構成を示すブロック図である。
【図２１】 図１８に示すＢ色画像処理部、Ｂ色差画像抽出部の詳細な回路構成を示すブロック図である。
【図２２】 図１８に示す波長選択型液晶カメラ装置の第１変形例で使用されるフルカラー波長選択光学系を示すブロック図である。
【図２３】 図１８に示す波長選択型液晶カメラ装置の第２変形例で使用されるフルカラー波長選択光学系を示すブロック図である。
【図２４】 本発明による各波長選択型液晶カメラ装置で使用される各液晶フィルタの液晶屈折率と透過特性との関係を示すグラフである。
【図２５】 本発明による各波長選択型液晶カメラ装置の油膜検出動作の一例を示す模式図である。
【図２６】 本発明による各波長選択型液晶カメラ装置を使用して、海面上に浮いている油膜を検出する際の検出範囲を説明する側面図である。
【図２７】 本発明による各波長選択型液晶カメラ装置を使用して、海面上に浮いている油膜を検出する際の検出範囲を説明する模式図である。
【図２８】 従来から知られている一般的なフルカラーカメラ装置の一例を示すブロック図である。
【図２９】 海面上に浮いている油膜をモデル化した断面図である。
【図３０】 図２９に示す中層が厚さ１μｍで、かつ光を吸収しないときにおける反射率と波長との関係を示すグラフである。
【図３１】 図２９に示す中層が厚さ１０μｍで、かつ光を吸収しないときにおける反射率と波長との関係を示すグラフである。
【図３２】 図２９に示す中層が厚さ１μｍで、かつ光を吸収するときにおける反射率と波長との関係を示すグラフである。
【図３３】 図２９に示す中層が厚さ１０μｍで、かつ光を吸収するときにおける反射率と波長との関係を示すグラフである。
【符号の説明】
１：波長選択型液晶カメラ装置、２：波長選択光学系、２ａ：波長選択光学系、２ｂ：波長選択光学系、３：画像処理部、４：差画像抽出部、５：液晶フィルタ、６：レンズ、７：撮像素子、８：透明基板、９：透明電極膜、１０：誘電体多層膜、１１：透明基板、１２：透明電極膜、１３：誘電体多層膜、１４：液晶層、１５：ヘッドアンプ回路、１６：映像処理回路、１７：Ａ／Ｄ変換回路、１８：フレームメモリ回路、１９：差分回路、２０：絶対値回路、２１：Ｄ／Ａ変換回路、２２：増幅回路、２３：光学的バンドパスフィルタ、２４：偏光フィルム、３０：波長選択型液晶カメラ装置、３１：波長選択光学系、３１ａ：波長選択光学系、３１ｂ：波長選択光学系、３１ｃ：波長選択光学系、３２：短波長側画像処理部、３３：短波長側差画像抽出部、３４：長波長側画像処理部、３５：長波長側差画像抽出部、３６：映像合成部、３７：液晶フィルタ、３８：レンズ、３９：入射面、４０：第２出射面、４１：反射透過面、４２：第１出射面、４３：全反射面、４４：ビームスプリッタ、４５：光学的バンドパスフィルタ、４６：短波長側撮像素子、４７：光学的バンドパスフィルタ、４８：長波長側撮像素子、４９：ヘッドアンプ回路、５０：映像処理回路、５１：Ａ／Ｄ変換回路、５２：フレームメモリ回路、５３：差分回路、５４：絶対値回路、５５：Ｄ／Ａ変換回路、５６：増幅回路、５７：ヘッドアンプ回路、５８：映像処理回路、５９：Ａ／Ｄ変換回路、６０：フレームメモリ回路、６１：差分回路、６２：絶対値回路、６３：Ｄ／Ａ変換回路、６４：増幅回路、６５：加算回路、６６：増幅回路、６７：プリズム型バンドパスフィルタ、６８：前面、６９：プリズム、７０：前面、７１：後面、７２：斜面、７３：斜面、７４：プリズム、７５：光学的ローパスフィルタ、７６：出射面、７７：光学的ハイパスフィルタ、７８：出射面、７９：光学的ローパスフィルタ、８０：入射面、８１：プリズム型ローパスフィルタ、８２：光学的ローパスフィルタ、８３：光学的ハイパスフィルタ、８４：前面、８５：プリズム、８６：前面、８７：後面、８８：斜面、８９：斜面、９０：プリズム、９１：光学的ローパスフィルタ、９２：入射面、９３：出射面、９４：全反射面、９５：出射面、９６：プリズム型ローパスフィルタ、９７：光学的バンドパスフィルタ、９８：光学的バンドパスフィルタ、９９：前面、１００：プリズム、１０１：前面、１０２：後面、１０３：斜面、１０４：斜面、１０５：プリズム、１０６：光学的ローパスフィルタ、１０７：入射面、１０８：出射面、１０９：全反射面、１１０：出射面、１１１：波長選択型液晶カメラ装置、１１２：フルカラー波長選択光学系、１１２ａ：フルカラー波長選択光学系、１１２ｂ：フルカラー波長選択光学系、１１３：Ｒ色画像処理部、１１４：Ｒ色差画像抽出部、１１５：Ｇ色画像処理部、１１６：Ｇ色差画像抽出部、１１７：Ｂ色画像処理部、１１８：Ｂ色差画像抽出部、１１９：エンコーダ回路、１２０：液晶フィルタ、１２１：レンズ、１２３：ダイクロイックプリズム、１２４：Ｒ色撮像素子、１２５：Ｇ色撮像素子、１２６：Ｂ色撮像素子、１２７：ヘッドアンプ回路、１２８：映像処理回路、１２９：Ａ／Ｄ変換回路、１３０：フレームメモリ回路、１３１：差分回路、１３２：絶対値回路、１３３：Ｄ／Ａ変換回路、１３４：増幅回路、１３５：ヘッドアンプ回路、１３６：映像処理回路、１３７：Ａ／Ｄ変換回路、１３８：フレームメモリ回路、１３９：差分回路、１４０：絶対値回路、１４１：Ｄ／Ａ変換回路、１４２：増幅回路、１４３：ヘッドアンプ回路、１４４：映像処理回路、１４５：Ａ／Ｄ変換回路、１４６：フレームメモリ回路、１４７：差分回路、１４８：絶対値回路、１４９：Ｄ／Ａ変換回路、１５０：増幅回路、１５１：光学的バンドパスフィルタ、１５２：偏光フィルム、１５３：海面、１５４：ヘリコプタ、１５５：ヘリコプタ、１５６：光軸、１５７：光線、１５８：光線、１５９：海面[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a wavelength-selective liquid crystal camera device that extracts a specific subject image by combining an optical bandpass filter and an image sensor, and in particular, the center wavelength of the transmission wavelength region depends on the input voltage. The present invention relates to a wavelength selective liquid crystal camera device that uses a changing liquid crystal filter to discriminate a light image from a subject into a plurality of wavelength regions and visualize an image such as an oil film floating on the sea surface.
[0002]
  [Summary of Invention]
  The present invention relates to a wavelength-selective liquid crystal camera device that extracts a specific image by combining an optical bandpass filter and an image sensor, and has an optical bandpass filter function, and the center wavelength is determined by voltage. A variable liquid crystal filter, one or a plurality of image sensors having a photoelectric conversion function provided after the liquid crystal filter, an optical system including a lens that sends the same optical image to the image sensor, and a plurality of different wavelengths For an image, by calculating a signal level difference for each pixel having the same spatial coordinates and configuring a wavelength selective liquid crystal camera device with an image calculation unit that outputs a value proportional to the absolute value, Imaging of foreign substances on the surface of liquid, such as oil film and organic film floating on the surface of the sea and water that were difficult to detect, solids such as metals and dielectrics Is to image the like uneven coating of transparent or semi-transparent film applied to imaging and solid surfaces of foreign materials present on the surface.
[0003]
[Prior art]
  Conventionally, a full-color camera device shown in FIG. 28 is known as one of wavelength selection type camera devices.
[0004]
  In the full-color camera device 200 shown in this figure, a dichroic prism 205 is provided between the lens 201 and each of the image pickup elements 202, 203, and 204, and white light 206 from the subject side is converted into three primary color lights R, G, and B. Has been broken down. In this case, as each of the imaging elements 202, 203, and 204, a CCD (Charge Coupled Device), a MOS (Metal Oxide Semiconductor), a CPD (Charge Priming Device), an SIT (Static Induction Transistor), a CMD (Charge Modulation Device), an AMI. A well-known individual imaging device such as (Amplified Mos Intelligent Imager) is used. In addition, imaging tubes such as planvicon, saticon, vidicon, carnicon, and harpicon are also used.
[0005]
  The video signals generated by the image sensors 202 to 204 are supplied to the head amplifier circuits 207, 208, and 209 and amplified, and various compensation processes are performed by the video processing circuits 210, 211, and 212. After that, it is synthesized by the encoder circuit 213, converted into a color television signal, and supplied to the next stage apparatus.
[0006]
  In this full-color camera device 200, an iris or ND (Neutral Density) filter that attenuates the amount of incident light, an IR (Infrared) filter that blocks infrared rays, a pulse generator that sends a pulse signal to a drive circuit or an image processing circuit, A contour compensation circuit for emphasizing the contour, a power source, and the like are also used, but these component parts are omitted because they are not related to the essence of the full-color camera device 200.
[0007]
[Problems to be solved by the invention]
  By the way, transparent foreign matter on the liquid surface such as oil film or organic film floating in fresh water or seawater, transparent foreign matter on the solid surface such as metal or dielectric, or transparent film or translucent applied on the solid surface Since the unevenness of coating has a refractive index close to that of water, it absorbs little light (especially long-wavelength light longer than visible light) when light absorption is small, and is visually distinguished from transparent substances such as water and glass. It is difficult to do.
[0008]
  Even if the absorption rate is large, when the film thickness is small, most of the light passes through the thin film, and it is difficult to visually distinguish it from a transparent substance such as water or glass. For example, in the case of an oil film floating in water, the water absorption rate (about 2.3 × 10 for green light)^-4cm^-1) Crude oil (absorption rate for green light is about 8cm)^-1: Reference [1] VMZOLOTAREV, IAKITUSHINA, and SMSUTOVSKIY, Optical Characteristics of Oils in the 0.4-15 μm Band, Oceanology Vol.17, No.6, pp.736-739 (1977).) In the case of 1 μm, at most 1% of light is absorbed.
[0009]
  For this reason, it is difficult to clearly distinguish between images of the sea surface and images of oil films, etc., with conventional wavelength selective camera devices that have been known so far, and it is possible to detect oil films and organic films floating in fresh water or sea water. Difficult to do.
[0010]
  Similarly, the full-color camera device 200 shown in FIG. 28 is intended to capture an image as close as possible to human visual characteristics, and thus cannot be easily detected by visual observation, such as the oil film or organic film floating on the water surface described above. Even if a subject is photographed, these cannot be detected as high-contrast images.
[0011]
  In addition, as a wavelength selection type camera device other than the full-color camera device 200, color filters that transmit light in a specific wavelength region and absorb light in other regions are installed before and after the lens of the full-color camera device. There is also a wavelength selective camera device.
[0012]
  However, this wavelength selection type camera device only narrows the wavelength selection region of the full-color camera device, and the imaging principle is the same as that of the full-color camera device 200 shown in FIG. 28. Therefore, the full-color camera device shown in FIG. Similar to the camera device 200, it is difficult to make an oil film or an organic film floating on the water surface into a high-contrast image.
[0013]
  Hereinafter, the reason will be described in detail with reference to the drawings, taking an oil film floating on the sea surface as an example.
[0014]
  When the oil film floats on the lake surface or the sea surface, as shown in FIG. 29, the upper layer (generally air) 215, the middle layer (liquid oil film or organic film) 216, and the lower layer (liquid such as fresh water or seawater) 217 It can be regarded as a layer structure. When the light 218 is incident on the middle layer 216 from the upper layer 215 side, the light 219 is emitted to the upper layer 215 side while being repeatedly reflected inside the thin film constituting the middle layer 216, and the light 220 is emitted to the lower layer 217 side. Radiated. Since many of these lights 219 (or light 220) interfere with each other, the intensity of light 219 reflected by the thin film and light 220 transmitted through the thin film has a weak wavelength dependency. Therefore, the oil film floating on the water surface can be regarded as a kind of antireflection film or antireflection film having poor performance.
[0015]
  Here, each refractive index of the upper layer 215, the middle layer 216, and the lower layer 217 is set to n₁, N₂, N₃And the absorptivity and thickness of the middle layer 216 are a and L, respectively, the intensity I of the reflected light from the middle layer 216 is
[Equation 1]
  I = [(r₁-R₂e^-2ad)²+ 4r₁r₂e^-2adsin²(Ψ / 2)] / [(1-r₁r₂e^-2ad)²+ 4r₁r₂e^-2adsin²(Ψ / 2)] ... (1)
Given in. Here, as shown in FIG. 29, ψ is a phase difference between adjacent reflected light beams (light 219), and when the wavelength of incident light 218 in vacuum is λ,
[Equation 2]
    ψ = (4πn₂d) [1- (n₁/ N₂)²sin²φ₁]^0.5/ Λ (2)
It can be expressed as However, in this equation (2), the incident angle of the light 218 incident from the upper layer 215 to the middle layer 216 is φ₁It was. Also, d is the optical path length when traversing the middle layer 216 only once, as shown in FIG.
[Equation 3]
    d = L / [1- (1-n₁/ N₂)²sin²φ₁]^0.5          ... (3)
It is represented by In addition, r₁Is the amplitude reflectivity at the interface between the upper layer 215 and the middle layer 216, r₂Is the amplitude reflectance at the interface between the middle layer 216 and the lower layer 217, and when the incident light 218 is P-wave light,
[Equation 4]
    r₁= Tan (φ₁−φ₂) / Tan (φ₁+ Φ₂)
    r₂= Tan (φ₃−φ₂) / Tan (φ₃+ Φ₂(4)
Given in. Where φ₂, Φ₃Is represented by the following equation.
[0016]
[Equation 5]
    φ₂= Sin^-1[(N₁/ N₂) Sinφ₁]
    φ₃= Sin^-1[(N₁/ N₃) Sinφ₁] (5)
[0017]
  When the incident light 218 is S wave light, r₁, R₂Is given by:
[0018]
[Equation 6]
    r₁= -Sin (φ₁−φ₂) / Sin (φ₁+ Φ₂)
    r₂= -Sin (φ₃−φ₂) / Sin (φ₃+ Φ₂(6)
[0019]
  Then, the relationship between the reflected light (light 219) from the intermediate layer 216 and the wavelength can be obtained from the equations (1) to (6). For example, the upper layer 215 may be air (n₁= 1), lower layer 217 is seawater (n₃= 1.33), the refractive index of the film which is the middle layer 216 is n₂= 1.5, the absorptance is “a = 0 cm^-1”, The normalized reflection intensity of the S wave light (hereinafter referred to as the reflectance of the intermediate layer 216) and the spectrum are shown in FIGS. 30 (a) to 30 (e) and FIGS. 31 (a) to 31 (e). 30 (a) to 30 (e), the thickness L of the middle layer 216 is “L = 1 μm”, and the thickness L of the middle layer 216 is “L = 10 μm” in FIGS. In this case, the refractive index dispersion of each layer is ignored. Here, a straight line having no wavelength dependency (broken line) indicates the reflectance of the sea surface without a film.
[0020]
  As is clear from these figures, when the sea surface is spatially and temporally constant and the intensity of the light 218 incident on the film is constant, the reflected light intensity from the film and the reflection from the sea surface without the film are as follows. In principle, it is possible to distinguish between the two by measuring the difference in light intensity.
[0021]
  However, in actuality, however, the height of the sea surface changes greatly both in terms of time and space, and the intensity of light 218 incident on the film varies greatly depending on the weather conditions and shooting direction. It is extremely difficult to determine the location of the film only by detecting the difference between the reflectance of the sea surface and the reflectance of the sea surface. This means that the incident angle φ₁Not only when the difference between the reflected light intensity from the film and the reflected light intensity from the sea surface without the film is very small, but also the incident angle φ₁This is the same even when is large.
[0022]
  Furthermore, in actual measurement, the reflectivity cannot be measured directly, the reflected light intensity must be measured, and the reflectivity must be calculated based on the measurement result. Thus, when the reflected light intensity is changing, unless a human intervenes in the determination, even if an oil film or the like floats on the sea surface, this cannot be recognized. Therefore, it has been pointed out that the conventional oil film detection method not only makes it impossible to automate the measurement, but also has a problem in reliability, such as a mistake in the oil film and the tide.
[0023]
  In the above description, the calculation is performed on the condition that the absorption of the film is negligible, and as shown in FIGS. 30 (a) to 30 (e) and 31 (a) to 31 (e), the reflection of the S wave light is performed. When the absorption is taken into consideration, for example, the absorption rate a of the film is set to “a = 8 cm.^-1"", The reflectivity of the intermediate layer 216 has wavelength dependency as shown in FIGS. 32A to 32E and FIGS. 33A to 33E. However, FIG. 33 is the case where the thickness L of the intermediate layer 216 is “L = 10 μm”, and the refractive index dispersion of each layer is ignored, where there is no wavelength dependence. The straight line (broken line) indicates the reflectance of the sea surface without a film.
[0024]
  As is clear from these figures, even when the absorption rate of the film is large, the dependence of the reflectance of the film is only slightly reduced, and FIGS. 30 (a) to 30 (e) and FIGS. 31 (a) to 31 (e). ) And there is no essential difference, just narrowing the wavelength region using an optical bandpass filter and simply photoelectrically converting it into an image with an image sensor as in a conventional wavelength selective camera device, Originally, an image with a very low contrast that is difficult or impossible to visually observe, such as an oil film floating on the sea surface, cannot be converted into an image with a high contrast that is easy to see.
[0025]
  For this reason, when it is necessary to detect oil films and organic films floating on the sea surface accurately and quickly, for example, when searching for damaged aircraft or ships, or accurately grasping the situation of crude oil spills from tankers, etc. However, there has been a strong demand for the development of a wavelength-selective camera device that cannot obtain an image of an oil film or the like and can obtain such an image.
[0026]
  Also, for the same reason, it is impossible to visualize oil film and organic film dirt on the surface of glass substrates such as liquid crystal displays and plasma displays, so flat displays such as liquid crystal displays and plasma displays are mass-produced. Since it is difficult to reduce the cost, development of a wavelength-selective camera device that can visualize oil film, organic film, and other dirt attached to the surface of glass substrates such as liquid crystal displays and plasma displays. Was strongly desired.
[0027]
  In view of the above circumstances, the present invention is an oil film or an organic film floating on the sea surface or the like even when the reflected light is strong, or an oil film or an organic film adhered to the surface of a glass substrate such as a liquid crystal display or a plasma display. The object of the present invention is to provide a wavelength-selective liquid crystal camera device that can image a high-contrast image and thereby reliably find the location of distress or dirt on a glass substrate.
[0028]
[Means for Solving the Problems]
  In order to achieve the above object, according to a first aspect of the present invention, there is provided a wavelength selective liquid crystal camera device that extracts a specific subject image by converting a light image obtained by a photographing operation into a light image for each wavelength region. A liquid crystal filter having an optical band-pass filter function, the center wavelength of which can be changed by voltage, and one imaging that generates a video signal by photoelectrically converting a light image in a wavelength region selected by the liquid crystal filter And an image calculation unit that calculates a signal level difference between two images having different wavelengths output from the image sensor and generates a video signal based on an absolute value of the difference. Yes.
[0029]
  According to a second aspect of the present invention, there is provided a wavelength selective liquid crystal camera device for extracting a specific subject image by converting an optical image obtained by a photographing operation into an optical image for each wavelength region, and having an optical bandpass filter function. The center wavelength is configured to be changeable by voltage, and from the optical image obtained by the imaging operation, the optical image of each wavelength region included in the short wavelength side and the optical image of each wavelength region included in the long wavelength side are the voltage. A liquid crystal filter that cyclically extracts in response to the light, and a short-wavelength-side image sensor that photoelectrically converts a light image in each wavelength region included on the short-wavelength side selected by the liquid crystal filter to generate a short-wavelength video signal And for each pixel of each short wavelength side video signal output from this short wavelength side image sensor, for each pixel having the same spatial coordinatesThe video signal of the current frame and the video signal of the previous frameA short-wavelength-side image calculation unit that calculates a signal level difference and generates a short-wavelength-side video signal based on the absolute value of the difference, and an optical image in each wavelength region included on the long-wavelength side selected by the liquid crystal filter For each pixel having the same spatial coordinate for each pixel of the long-wavelength side image signal output from the long-wavelength side image sensor. InThe video signal of the current frame and the video signal of the previous frameA long wavelength side image calculation unit that calculates a signal level difference and generates a long wavelength side video signal based on the absolute value of the difference, and the long wavelength side video signal output from the long wavelength side image calculation unit and the short wavelength side image signal And a video signal synthesis unit that synthesizes the short-wavelength video signal output from the wavelength-side image calculation unit to generate a synthesized video signal.
[0030]
  According to a third aspect of the present invention, in the wavelength selection type liquid crystal camera device for extracting a specific subject image by converting the optical image obtained by the photographing operation into an optical image for each wavelength region, and having an optical bandpass filter function. The center wavelength is configured to be changeable by voltage, and from the optical image obtained by the imaging operation, the optical image of each wavelength region included in the short wavelength side and the optical image of each wavelength region included in the long wavelength side are the voltage. A liquid crystal filter that extracts cyclically according to the wavelength, and a light image in each of the short wavelength side and the long wavelength side selected by the liquid crystal filter is displayed in a red (R) region, a green (G) region, and a blue (B) And a photoelectric converter for separating the R light image, the G light image, and the B light image in each of the short wavelength side and the long wavelength side separated by the separation unit. , Short wavelength side and long wavelength side R color image signal wavelength range, G color video signal, and a color image sensor for generating a B color image signal, outputted from the color image sensorThe R-color video signal, G-color video signal, and B-color video signal for each wavelength region on the short wavelength side and the R-color video signal, the G-color video signal, and the B-color video signal for each wavelength region on the long wavelength side are in units of pixels. Compare withFor each of R, G, and B colors, a signal level difference is calculated for each pixel having the same spatial coordinates, and based on the absolute value of this difference, an R color video signal, a G color video signal, and a B color are calculated. A color image calculation unit that generates a video signal, and a color video signal combination unit that generates a combined color video signal by combining the R color video signal, the G color video signal, and the B color video signal output from the color image calculation unit It is characterized by having.
[0031]
  Claim 4ThenAny one of Claims 1-3In the wavelength selective liquid crystal camera device described inThe imaging device, the short wavelength side imaging device and the long wavelength side imaging device, or the color imaging device of the wavelength selection type liquid crystal camera devicePlace an optical shutter before and operate this optical shutterTo intermittently visualizeIt is characterized by that.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
    << Description of the First Embodiment of the Invention >>
    <Basic description of the first embodiment>
  FIG. 1 shows a wavelength selective liquid crystal camera device according to the present invention.First embodimentFIG. In this figure, in order to simplify the description, parts that are not related to the description of the present invention, such as an iris and an ND filter that attenuate the amount of incident light, components necessary for configuring the camera device, and a drive circuit. A pulse generation circuit that sends a pulse signal to a video processing circuit, a contour compensation circuit that emphasizes the contour of a video, a power supply circuit, and the like are omitted.
[0033]
  A wavelength selection type liquid crystal camera device 1 shown in this figure includes a wavelength selection optical system 2, an image processing unit 3, and a difference image extraction unit 4. The wavelength selection optical system 2 takes in an optical image obtained by photographing a subject such as the sea surface where an oil film is floated, extracts light in a specified wavelength range, photoelectrically converts it, and outputs a short wavelength range video signal, Wavelength range video signals are generated cyclically sequentially. The image processing unit 3 sequentially generates a short-wavelength video signal and a long-wavelength video signal obtained by performing image processing on the short-wavelength video signal and the long-wavelength video signal output from the wavelength selection optical system 2. The difference image extraction unit 4 stores at least one of the short wavelength region video signal and the long wavelength region video signal output from the image processing unit 3 in units of frames, and the short wavelength region image signal and the long wavelength region image. Based on the difference from the signal, a video signal having a high contrast such as an oil film image or an organic film image floating on the sea surface or water surface is generated and supplied to a display device (not shown).
[0034]
  The wavelength selection optical system 2 includes a liquid crystal filter 5, a lens 6, and an image sensor 7. The liquid crystal filter 5 has an optical band-pass filter function, captures a light image (white light image) from a subject, and an optical image in a short wavelength region that forms the light image according to an input AC voltage. And a long-wavelength light image constituting the light image are sequentially extracted. The lens 6 forms an image of light in the wavelength region selected by the liquid crystal filter 5 backward by a predetermined distance. The imaging device 7 is a solid-state imaging device using silicon, such as CCD, MOS, CPD, SIT, and AMI, or a solid-state imaging device using a material that exhibits high sensitivity in the infrared region, such as GaAs and InGaAs, or amorphous selenium, Each light image emitted from the lens 6 is composed of either a solid-state image sensor using a material exhibiting high sensitivity with ultraviolet rays or short-wavelength visible light, or an imaging tube such as a planbicon, a saticon, a vidicon, a carnicon, or a harpicon. The light / electric conversion is performed, and the short wavelength image signal and the long wavelength image signal obtained thereby are sequentially supplied to the image processing unit 3.
[0035]
  As shown in FIG. 2, the liquid crystal filter 5 is formed by sequentially laminating a transparent substrate 8, a transparent electrode film 9, and a dielectric multilayer film 10, and a transparent substrate 11, a transparent electrode film 12, and a dielectric multilayer film. The film 13 is sequentially laminated, and the liquid crystal layer 14 is interposed between the dielectric multilayer film 13 and the dielectric multilayer film 10. The transparent electrode film 9 is composed of a metal film or the like laminated on one surface side of the transparent substrate 8 and is connected to a ground point. The dielectric multilayer films 10 and 11 are formed by stacking a required number of dielectric films having a refractive index corresponding to the reflectance and effective wavelength region on the transparent electrode film 9 or 12, and functioning as a kind of mirror. The transmission wavelength range is determined based on the same principle as the Perot interferometer. The transparent electrode film 12 is composed of a metal film or the like laminated on one surface side of the transparent substrate 11, and an AC voltage is applied from the outside. The liquid crystal layer 14 is composed of a nematic liquid crystal, a cholesteric liquid crystal, a smectic liquid crystal, a twisted nematic liquid crystal, an electric field control birefringence mode liquid crystal (Electrically Controllable Birefringence) liquid crystal, a surface stabilized ferroelectric liquid crystal, or the like.
[0036]
  The liquid crystal filter 5 captures a light image (white light image) from the subject and has a constant amplitude as shown in FIGS. When a burst-like AC voltage synchronized with a vertical synchronization signal is applied to the transparent electrode film 12, a plurality of light images belonging to a short wavelength region and a plurality of light images belonging to a long wavelength region are cyclically sequentially. Extract and enter the lens 6.
[0037]
  At this time, the alignment direction of the liquid crystal constituting the liquid crystal layer 14 is homogeneous alignment in which the long axis of the liquid crystal molecules is parallel to each surface of the transparent substrates 8 and 11 or the long axis of the liquid crystal molecules is the transparent substrates 8 and 11. One of the homeotropic orientations which is substantially perpendicular to each surface of the film. However, in the former liquid crystal array, the dielectric anisotropy needs to be “positive”, and in the latter liquid crystal array, the dielectric anisotropy needs to be “negative”.
[0038]
  Table 1 shows the relationship between the refractive index dispersion of general fresh water and the wavelength. Table 2 shows an example of the wavelength selection operation of the wavelength selection type liquid crystal camera device shown in FIG.
  The upper layer side of the subject is air (refractive index n₁= 1) If the lower layer is fresh water having a refractive index dispersion as shown in Table 1 (a table cited from the scientific chronology), the difference in reflectance from the fresh water is 1% or less, so that As shown, as the transmission wavelength region of the liquid crystal filter 5 shifts to the short wavelength side, the central wavelength λ of the transmission wavelength region of the liquid crystal filter 5 when a burst-like AC voltage is input.₁And the center wavelength λ of the transmission wavelength region of the liquid crystal filter 5 when no burst-like AC voltage is input.₂Absolute value of difference | λ₁−λ₂The center wavelength λ of the liquid crystal filter 5 so that |₁And the center wavelength λ₂Value is determined. Note that the values shown in Table 2 are only a guide, and each center wavelength λ of the liquid crystal filter 5 is shown.₁, Λ₂May slightly deviate from these values.
[0039]
[Table 1]

[Table 2]

[0040]
  As shown in FIG. 4, the image processing unit 3 includes a head amplifier circuit 15, a video processing circuit 16, and an A / D conversion circuit 17. The head amplifier circuit 15 amplifies the short wavelength region video signal and the long wavelength region image signal sequentially output from the wavelength selection optical system 2 with a constant amplification factor. The video processing circuit 16 performs preset image processing, for example, transmission region compensation processing of the liquid crystal filter 5, liquid crystal filter, and the like on the short wavelength video signal and the long wavelength video signal sequentially output from the head amplifier circuit 15. 5 transmittance compensation processing is performed. The A / D conversion circuit 17 performs A / D conversion on the short-wavelength video signal and the long-wavelength video signal sequentially output from the video processing circuit 16, and digitizes the short-wavelength video signal and the long-wavelength video. A signal is generated and supplied to the difference image extraction unit 4.
[0041]
  The difference image extraction unit 4 includes a frame memory circuit 18, a difference circuit 19, an absolute value circuit 20, a D / A conversion circuit 21, and an amplification circuit 22. The frame memory circuit 18 is based on the input vertical synchronization signal, and the digitized short wavelength range video signal and long wavelength range video signal output from the image processing unit 3 are set in a preset wavelength range. While a video signal, for example, a short-wavelength video signal is captured and stored in units of frames, when the long-wavelength video signal is output from the image processing unit 3, the stored short-wavelength video signal is synchronized with the video signal. Output. The difference circuit 19, based on the input vertical synchronization signal, outputs the short wavelength region video signal output from the frame memory circuit 18 and the digitized long wavelength region image signal output from the image processing unit 3 in units of pixels. Comparing and calculating the level difference between the pixels of the same spatial coordinates to show the difference between the short wavelength image signal and the long wavelength image signal, for example, the image of the oil film floating on the water surface or the organic film A video signal with high contrast such as video is generated. The absolute value circuit 20 calculates the absolute value of the video signal output from the difference circuit 19. The D / A conversion circuit 21 converts the digital signal format video signal output from the absolute value circuit 20 into an analog signal format video signal. The amplification circuit 22 amplifies the video signal output from the D / A conversion circuit 21 and supplies the amplified video signal to the display device.
[0042]
  Next, the operation of this embodiment will be described with reference to FIGS.
[0043]
  First, when the wavelength-selective liquid crystal camera device 1 shoots the sea surface where an oil film is floated, a light image from a subject is captured by the liquid crystal filter 5 of the wavelength-selective optical system 2 provided in the wavelength-selective liquid crystal camera device 1. (White light image) is captured, and in accordance with the input AC voltage, the short-wavelength light image constituting the light image and the long-wavelength light image constituting the light image are sequentially extracted cyclically. The
[0044]
  Then, an image is formed on the image sensor 7 by the lens 6, and the short wavelength region video signal and the long wavelength region image signal obtained thereby are sequentially supplied to the image processing unit 3, and these short wavelength region image signals, Pre-amplification processing, transmission region compensation processing of the liquid crystal filter 5 and transmittance compensation processing of the liquid crystal filter 5 are performed on the long wavelength region video signal, and the short wavelength region video signal and long wavelength region image obtained thereby are obtained. The signal is digitized and supplied to the difference image extraction unit 4.
[0045]
  In this case, as shown in FIG. 3B, in the case of the frames A, C, E, G, and I of the video signal, a burst-like AC voltage is applied to the liquid crystal filter 5 as shown in FIG. Is applied. For this reason, the refractive index of the liquid crystal constituting the liquid crystal layer 14 is changed, and the center frequency of the liquid crystal filter 5 which is a kind of Fabry-Perot interferometer is changed to form a light image from the subject. A plurality of optical images belonging to the short wavelength region are extracted from the optical images in the respective wavelength regions, and are formed on the image sensor 7 to generate a short wavelength region video signal, which is supplied to the image processing unit 3. The
[0046]
  Also, as shown in FIG. 3B, in the case of frames B, D, F, H, and J of the video signal, as shown in FIG. Not applied. For this reason, the refractive index of the liquid crystal constituting the liquid crystal layer 14 is restored to the original, and the center frequency of the liquid crystal filter 5 which is a kind of Fabry-Perot interferometer is changed to form an optical image from the subject. Of the optical images in each wavelength region, each optical image belonging to the long wavelength region is extracted and imaged on the image sensor 7 to generate a long wavelength region video signal, which is supplied to the image processing unit 3. The
[0047]
  When the digitized short wavelength region video signal is output from the image processing unit 3, the short wavelength region video signal is converted by the frame memory circuit 18 of the difference image extraction unit 4 based on the input vertical synchronization signal. When the digitized long wavelength image signal is output from the image processing unit 3 after being captured and stored, the difference circuit 19 and the absolute value circuit 20 cause the long wavelength image signal and the frame memory circuit 18 to be output. Are compared with each other in the pixel unit, and the level difference between each pixel of the same spatial coordinate is calculated, and the short wavelength region image signal and the long wavelength region image signal obtained thereby are calculated. | A−B |, | B−C |, | C−D |, | D−E |, | E−F |,... Video signals (for example, an image of an oil film floating on the water surface, Contrast such as organic film images Kushida together with the video signal) is generated, D / A conversion circuit 21, the video signal by the amplification circuit 22 is an analog of, is supplied to the display device.
[0048]
  At this time, a nematic liquid crystal having a thickness of 2 μm and having an ordinary light refractive index of “1.5” and an extraordinary light refractive index of “1.7” is used as the liquid crystal filter 5, and each dielectric multilayer is used. Assuming that a liquid crystal filter having a power reflectivity of 0.9 for the films 10 and 13 is used and only abnormal light is selected by the polarizing plate by the liquid crystal filter 5, a burst AC voltage is applied to the liquid crystal filter 5. Before the liquid crystal molecules are aligned substantially perpendicularly to the transparent substrates 8 and 11, as shown by a thick solid line in FIG. 5F, the liquid crystal molecules are about 2 nm from the short wavelength region to the long wavelength region. A plurality of transmission regions having a full width at half maximum (in FIG. 5, approximated by a straight line for the sake of simplicity) can be obtained, and the liquid crystal can be observed so that extraordinary light has an effective refractive index of “1.53”. Filter 5 has burst AC voltage When applied, as shown by the thin solid line in FIG. 5 (f), the full width at half maximum of about 2 nm from the short wavelength region to the long wavelength region (in FIG. 5, it is approximated by a straight line for simplicity). A plurality of transmissive regions having can be obtained.
[0049]
  Strictly speaking, as shown in the example of the refractive index dispersion of water shown in Table 1 because the refractive index dispersion of seawater changes, the amount of change is very small. In the wavelength region, the refractive index dispersion of water may be ignored, and as shown in FIGS. 5 (a) to 5 (e), the reflectance of the sea surface without an oil surface has almost no wavelength dependency. If the movement range of the central wavelength of the liquid crystal filter 5 (spectrum difference between the thick solid line and the thin solid line shown in FIG. 5 (f)) is within the lower range of Table 2, even if the wavelength is different, the liquid crystal filter 5 The selected light images are at the same level.
[0050]
  As a result, when there is no oil film on the sea surface, the short wavelength image signal and the long wavelength image signal output from the image processing unit 3 are at the same level in units of pixels, and zero is output from the difference image extracting unit 4. The video signal shown is output.
[0051]
  On the other hand, as shown in FIGS. 5A to 5E, in seawater with an oil film, the reflectivity of the oil film varies greatly depending on the wavelength regardless of the incident angle, but an alternating voltage is applied. When the reflectance of the wavelength region having a transmittance of 1 / e or more with respect to the transmittance (maximum transmittance) of the center wavelength of the optical image transmitted through the liquid crystal filter 5 is not applied Since the reflectance of the wavelength region having a transmittance of 1 / e or more is different from the transmittance (maximum transmittance) of the central wavelength of the optical image transmitted through the liquid crystal filter 5, the oil level When a certain seawater surface is photographed, the short wavelength image signal output from the image processing unit 3 and the long wavelength image signal are at different levels in units of pixels, and the difference image extraction unit 4 indicates an oil film. Is output.
[0052]
  At this time, the frame time difference between the light image in the short wavelength region and the light image in the long wavelength region output from the liquid crystal filter 5 is 1/30 second, and usually the sea surface is almost stationary within this time. Therefore, for each pixel constituting the short wavelength region video signal and each pixel constituting the long wavelength region image signal, calculation can be performed for each pixel having the same spatial coordinates. For this reason, even if the sea surface is rippled, it is considered that the level difference between two frames is calculated for each neighboring pixel separated by several pixels, and the incident angle does not change significantly within this range. Even when the sea surface is calm, or when the sea surface is waved by strong winds, an oil film on the sea surface can be detected.
[0053]
  As described above, in this embodiment, the wavelength selection optical system 2 shoots the sea surface where the oil film is floated, and while sequentially generating the short wavelength video signal and the long wavelength video signal sequentially, The image processing unit 3 performs image processing on the short-wavelength video signal and the long-wavelength video signal to generate a digitized short-wavelength video signal and a digitized long-wavelength video signal. The extraction unit 4 extracts the difference between the short wavelength video signal and the long wavelength video signal, and generates a video signal with high contrast such as an oil film image or an organic film image floating on the water surface. Since it is supplied to the display device, it is possible to detect an oil film, an organic film, etc. on the water surface, which has been difficult to detect, as a high-contrast image.it can.
[0054]
  Thus, conventionally, even when searching for a distressed site by visual observation from a helicopter or an aircraft, it is difficult to find an oil film, for example, when the reflected light from the sea is strong (backlit state), in the case of rainy weather, Even when the water level is high, regardless of the state of the sea surface, when an oil film such as a damaged aircraft or ship floats on the sea surface, it is possible to reliably detect this and find the disaster site.
[0055]
  In this embodiment, the video signal output from the difference image extraction unit 4 is set to a value other than zero only when there is an oil film or an organic film on the photographed sea surface. The video signal output from the extraction unit 4 is guided to a determination circuit provided in the next-stage device or the like, and it is easily determined whether or not a preset threshold value is exceeded. can do. As a result, a plurality of wavelength selective liquid crystal camera devices 1 shown in FIG. 1 are installed in a helicopter, an aircraft, etc., and each wavelength selective liquid crystal camera device 1 automatically searches for all directions to automatically detect the presence or absence of an oil film or the like. If judged, the search efficiency can be greatly improved compared to the case of conventional visual observation, and quick disaster relief can be performed.it can.
[0056]
  In addition, by combining the wavelength selective liquid crystal camera device 1 shown in FIG. 1 and a GPS (Global Positioning System) device, the position of the oil film can be determined instantaneously, thereby further finding the location of the distress, In addition to speeding up, it is possible to easily map the situation of oil spills such as tankers in real time.
[0057]
    <First Modification of First Embodiment>
  Further, in the wavelength selective liquid crystal camera device 1 shown in FIG. 1, the liquid crystal filter 5 alternately extracts the short-wavelength light image and the long-wavelength light image included in the light image from the subject, The optical image in the short wavelength region and the optical image in the long wavelength region are formed on the image sensor 7 by the lens 6. However, as shown in FIG. The wavelength selective optical system 2a in which the optical bandpass filter 23 is disposed is used to band-pass the short-wavelength optical image and the long-wavelength optical image selected by the liquid crystal filter 5 with the optical bandpass filter 23. Filtering may narrow down the wavelength range and form an image on the image sensor 7.
[0058]
  However, it is necessary to make the full width at half maximum (full width half maximum) of the optical bandpass filter 23 wider than the full width at half maximum of the liquid crystal filter 5.
[0059]
  Even in this case, similar to the wavelength selective liquid crystal camera device 1 shown in FIG. 1, it is possible to detect an oil film, an organic film, etc. on the water surface as an image with high contrast, which has heretofore been difficult to detect.it can.
[0060]
  In the first modification, the optical bandpass filter 23 is arranged between the lens 6 and the image sensor 7. However, if it is in front of the image sensor 7, it is in front of the liquid crystal filter 5. Even if the optical band-pass filter 23 is arranged on the liquid crystal filter 5 or the optical band-pass filter 23 is arranged behind the liquid crystal filter 5, the same effect as in the first modification can be obtained.
[0061]
    <Second Modification of First Embodiment>
  Further, in the wavelength selection type liquid crystal camera device 1 shown in FIG. 1, when an alternating voltage is not applied, a light beam that senses only the ordinary light refractive index of the liquid crystal is selected, and when an alternating voltage is applied, the ordinary light refractive index. And the extraordinary refractive index are selected so that each ray is incident on the image sensor 7. As shown in FIG. 7, behind the liquid crystal filter 5, a polarizing film (or It is also possible to use the wavelength selection optical system 2b in which the polarizing plate) 24 is disposed, and to remove the light beam that senses only the ordinary light refractive index by the polarizing film 24 and make it incident on the image sensor 7.
[0062]
  Even in this case, similar to the wavelength selective liquid crystal camera device 1 shown in FIG. 1, it is possible to detect an oil film, an organic film, etc. on the water surface as an image with high contrast, which has heretofore been difficult to detect.it can.
[0063]
  In the second modification, the polarizing film 24 is disposed between the liquid crystal filter 5 and the lens 6. However, in front of the image sensor 7, the liquid crystal filter 5 and the lens 6 are provided. Even if the polarizing film 24 is disposed behind the same, the same effect as that of the second modification can be obtained.
[0064]
    <Third Modification of First Embodiment>
  Further, in the wavelength selection type liquid crystal camera device 1 shown in FIG. 1, the wavelength selection type optical system 2, the image processing unit 3, and the difference image extraction unit 4 are placed in one housing to constitute the camera device. However, all of the difference image extraction unit 4 and all or a part of the image processing unit 3 may be separated from the camera device.
[0065]
  By doing so, the camera device portion can be reduced in size and weight, and handling and operation of the camera device can be facilitated.
[0066]
    << Description of the Second Embodiment of the Invention >>
    <Basic description of the second embodiment>
  FIG. 8 shows a wavelength selective liquid crystal camera device according to the present invention.2nd Embodiment is shownIt is a block diagram. In this figure, in order to simplify the description, parts that are not related to the description of the present invention, such as an iris and an ND filter that attenuate the amount of incident light, components necessary for configuring the camera device, and a drive circuit. A pulse generation circuit that sends a pulse signal to a video processing circuit, a contour compensation circuit that emphasizes the contour of a video, a power supply circuit, and the like are omitted.
[0067]
  The wavelength selection type liquid crystal camera device 30 shown in this figure includes a wavelength selection optical system 31, a short wavelength side image processing unit 32, a short wavelength side difference image extraction unit 33, a long wavelength side image processing unit 34, and a long wavelength. A side difference image extraction unit 35 and a video composition unit 36 are provided. The wavelength selection optical system 31 captures and divides the optical image from the subject into two equal parts, extracts the optical image in the short wavelength region and the optical image in the long wavelength region, photoelectrically converts the optical image, and A long wavelength side video signal is generated for an optical image in the long wavelength region. The short wavelength side image processing unit 32 sequentially generates short wavelength side video signals obtained by performing image processing on the short wavelength side video signals sequentially output from the wavelength selection optical system 31. The short wavelength side difference image extraction unit 33 stores the short wavelength side video signal output from the short wavelength side image processing unit 32 in units of frames, while the short wavelength side video signal of the current frame and the short wavelength side one frame before are stored. Based on the difference from the video signal, a short-wavelength video signal having a high contrast such as an oil film image or an organic film image floating on the sea surface or the water surface is generated and supplied to the video synthesis unit 36. The long wavelength side image processing unit 34 sequentially generates long wavelength side video signals obtained by performing image processing on the long wavelength side video signals sequentially output from the wavelength selection optical system 31. The long wavelength side difference image extraction unit 35 stores the long wavelength side video signal output from the long wavelength side image processing unit 34 in units of frames, while the long wavelength side video signal of the current frame and the long wavelength one frame before Based on the difference from the side video signal, a long wavelength side video signal having a high contrast such as an oil film image or an organic film image floating on the sea surface or the water surface is generated. The video synthesizing unit 36 adds the short wavelength side video signal output from the short wavelength side difference image extracting unit 33 and the long wavelength side video signal output from the long wavelength side difference image extracting unit 35 to add a synthesized television signal. Is generated.
[0068]
  The wavelength selection optical system 31 includes a liquid crystal filter 37, a lens 38, and a beam splitter 44. The liquid crystal filter 37 is configured in the same manner as each of the liquid crystal filters 5 shown in FIG. 1, captures a light image (white light image) from the subject, and according to the input AC voltage, Extract a long-wavelength light image. The lens 38 forms a light image in a short wavelength region and a light image in a long wavelength region selected by the liquid crystal filter 37, and forms a rearward image by a predetermined distance. The beam splitter 44 transmits half of the short-wavelength light image incident on the incident surface 39 and half of the long-wavelength light image to be emitted from the second emission surface 40, and the short-wavelength light image. The reflection / transmission surface 41 that reflects the remaining half of the light and the remaining half of the light image in the long wavelength region, the light image in the short wavelength region and the light image in the long wavelength region reflected by the reflection / transmission surface 41 are totally reflected, A short-wavelength light image, a short-wavelength light image, and a long-wavelength light image that are in the same horizontal direction as the long-wavelength light image are emitted from the first light-exiting surface 42. The short-wavelength light image and the long-wavelength light image collected by the lens 38 are divided into two equal parts and output from the first emission surface 42 and the second emission surface 40, respectively. To do.
[0069]
  Further, the wavelength selection optical system 31 includes an optical bandpass filter 45, a short wavelength side imaging device 46, an optical bandpass filter 47, and a long wavelength side imaging device 48. The optical bandpass filter 45 transmits the light image on the short wavelength region side emitted from the first emission surface 42 of the beam splitter 44. The short-wavelength-side imaging device 46 is a solid-state imaging device using silicon, such as CCD, MOS, CPD, SIT, AMI, or the like, or a solid-state imaging device using a material having high sensitivity in the infrared region such as GaAs, InGaAs, or amorphous. Consists of either a solid-state imaging device using a material that exhibits high sensitivity to ultraviolet rays or short-wavelength visible light, such as selenium, or an imaging tube such as planvicon, sachicon, vidicon, carnicon, harpicon, etc. The emitted light image on the short wavelength region side is optically / electrically converted, and short wavelength side video signals are sequentially generated cyclically. The optical bandpass filter 47 transmits the light image on the long wavelength region side emitted from the second emission surface 40 of the beam splitter 44. The long-wavelength-side image sensor 48 is configured in the same manner as the short-wavelength-side image sensor 46, and optically / electrically converts the long-wavelength region side optical image emitted from the optical bandpass filter 47 to convert the long-wavelength-side image signal. Generate cyclically sequentially.
[0070]
  At this time, each optical path length in the beam splitter 44 is set so that the optical path length between the lens 38 and the short wavelength side imaging device 46 is equal to the optical path length between the lens 38 and the long wavelength side imaging device 48. Is set.
[0071]
  As shown in FIG. 9, the short wavelength side image processing unit 32 includes a head amplifier circuit 49, a video processing circuit 50, and an A / D conversion circuit 51, and the short wavelength side output from the wavelength selection optical system 31. Pre-amplification processing, transmission region compensation processing of the liquid crystal filter 37, transmittance compensation processing of the liquid crystal filter 37, etc. are performed on the video signal, and the short-wavelength video signal obtained thereby is digitized to produce a short-wavelength side difference. This is supplied to the image extraction unit 33. The head amplifier circuit 49 amplifies the short wavelength video signals sequentially output from the wavelength selection optical system 31 with a constant amplification factor. The video processing circuit 50 performs preset image processing such as transmission region compensation of the liquid crystal filter 37 and transmittance compensation of the liquid crystal filter 37 on the short wavelength side video signals sequentially output from the head amplifier circuit 49. . The A / D conversion circuit 51 performs A / D conversion on the short-wavelength video signals sequentially output from the video processing circuit 50 to generate a digitized short-wavelength video signal.
[0072]
  The short-wavelength side difference image extraction unit 33 includes a frame memory circuit 52, a difference circuit 53, an absolute value circuit 54, a D / A conversion circuit 55, and an amplification circuit 56, and is inputted with vertical synchronization. When the short wavelength side video signal output from the short wavelength side image processing unit 32 is output based on the signal, the short wavelength side image signal is captured and stored, and also digitized from the short wavelength side image processing unit 32 When a video signal is output, this short wavelength side video signal and the stored short wavelength side video signal of the previous frame are compared in pixel units, and the level difference between each pixel of the same spatial coordinate is calculated. Thus, the short-wavelength difference video signal indicating the difference between the two signals obtained in this way (for example, the short-wavelength video signal with a high contrast such as an oil film image or an organic film image floating on the water surface) is analogized. Amplification After supplied to the video synthesizing unit 36.
[0073]
  Further, as shown in FIG. 10, the long wavelength side image processing unit 34 includes a head amplifier circuit 57, a video processing circuit 58, and an A / D conversion circuit 59. The head amplifier circuit 57 amplifies the long wavelength video signals sequentially output from the wavelength selection optical system 31 with a constant amplification factor. The video processing circuit 58 performs preset image processing, for example, transmission region compensation of the liquid crystal filter 37, transmittance compensation of the liquid crystal filter 37, and the like on the long wavelength side video signals sequentially output from the head amplifier circuit 57. . The A / D conversion circuit 59 performs A / D conversion on the long-wavelength video signals sequentially output from the video processing circuit 58, generates a digitized long-wavelength video signal, and generates a long-wavelength side difference image extraction unit. 35.
[0074]
  The long-wavelength side difference image extraction unit 35 includes a frame memory circuit 60, a difference circuit 61, an absolute value circuit 62, a D / A conversion circuit 63, and an amplification circuit 64. On the basis of this, when the long wavelength side video signal output from the long wavelength side image processing unit 34 is output, the long wavelength side video signal is captured and stored, and digitized from the long wavelength side image processing unit 34 Is output, the long-wavelength video signal is compared with the stored long-wavelength video signal one frame before in pixel units, and the level difference between the pixels of the same spatial coordinates is calculated. The long wavelength side video signal indicating the difference between the long wavelength side video signal and the long wavelength side video signal obtained by this (for example, the long wavelength side with a high contrast such as the image of the oil film floating on the water surface or the image of the organic film) Video signal) After amplified analog of supplies to video synthesis unit 36.
[0075]
  As shown in FIG. 8, the video composition unit 36 includes an addition circuit 65 and an amplification circuit 66. The adder circuit 65 adds the short wavelength side video signal output from the short wavelength side difference image extraction unit 33 and the long wavelength side video signal output from the long wavelength side difference image extraction unit 35 to obtain a composite television signal. Generate. The amplifying circuit 66 amplifies the synthesized television signal output from the adding circuit 65 and supplies it to a display device or the like, thereby imaging an oil film image or the like.
[0076]
  As described above, in this embodiment, the wavelength selection optical system 31 shoots the sea surface where the oil film is floated and the like, while sequentially generating the short wavelength side video signal and the long wavelength side video signal, The image processing unit 32 and the long wavelength side image processing unit 34 perform image processing on the short wavelength side video signal and the long wavelength side video signal, and digitize the short wavelength side video signal and the long wavelength side video signal. After the generation, the difference between the short-wavelength side video signal and the short-wavelength side video signal is extracted by the short-wavelength side difference image extraction unit 33, and the contrast of the oil film image or the organic film image floating on the water surface is obtained. In addition to generating an increased short wavelength side video signal, the long wavelength side difference image extraction unit 35 extracts the difference between the long wavelength side video signal and the long wavelength side video signal, and the image of the oil film floating on the water surface or the like Contrast such as organic film images Since the high-wavelength side video signal is generated and the combined television signal is synthesized and supplied to the display device, no matter what the state of the water surface is, the oil film or organic film on the water surface Can be detected as an image with high contrast.it can.
[0077]
  Conventionally, even when searching for a distressed site by visual observation from a helicopter or an aircraft, when it is difficult to find an oil film, for example, when the reflected light from the sea surface is strong (backlit state), in the case of rainy weather, Even if it is high, regardless of the state of the sea surface, when an oil film such as a damaged aircraft or ship floats on the sea surface, it is possible to reliably detect this and find the disaster site.
[0078]
  In this embodiment, the short-wavelength video signal output from the short-wavelength side difference image extraction unit 33 and the long-wavelength side difference image extraction unit 35 only when there is an oil film or an organic film on the photographed sea surface. Since the long-wavelength video signal is set to a value other than zero, the synthesized television signal output from the video synthesizing unit 36 is guided to a determination circuit (not shown), and a preset threshold value is set. It is possible to easily automate the search for the site of distress simply by determining whether or not the distance is exceeded. As a result, a plurality of wavelength selective liquid crystal camera devices 30 shown in FIG. 8 are installed in a helicopter, an aircraft, etc., and each wavelength selective liquid crystal camera device 30 searches for all directions at the same time and automatically determines the presence or absence of an oil film or the like. Compared with the case of conventional visual inspection, the search efficiency can be greatly improved and quick disaster relief can be performed.it can.
[0079]
  In addition, by combining the wavelength selective liquid crystal camera device 30 shown in FIG. 8 and a GPS (Global Positioning System) device, the position of the oil film can be determined instantaneously, thereby further discovering the distressed site, etc. In addition to speeding up, it is possible to easily map the situation of oil spills such as tankers in real time.
[0080]
    <First Modification of Second Embodiment>
  Further, in the wavelength selection type camera device 30 shown in FIG. 8, the liquid crystal filter 37, the lens 38, the beam splitter 44, the two optical bandpass filters 45 and 47, the short wavelength side imaging device 46, and the long wavelength Although the wavelength selection optical system 31 comprised by the side image pick-up element 48 is used, as shown in FIG. 11, the liquid crystal filter 37, the lens 38, the prism type band pass filter 67, and the short wavelength side A wavelength selection optical system 31a configured by the image sensor 46 and the long wavelength side image sensor 48 may be used.good.
[0081]
  In this case, the prism type bandpass filter 67 includes a prism 69, a prism 74, an optical low-pass filter 75, an optical high-pass filter 77, and an optical low-pass filter 79. The prism 69 is a prism whose front surface 68 side is cut at 45 degrees. The prism 74 is a parallelogram-shaped prism cut so that the angle formed by the front surface 70 (rear surface 71) and the inclined surfaces 72 and 73 is 45 degrees and 135 degrees. The optical low-pass filter 75 is disposed on the joint surface between the slope 73 of the prism 74 and the front surface 68 of the prism 69, and has a low-pass characteristic as shown in FIGS. The optical image belonging is transmitted, and the optical image belonging to the short wavelength region is reflected. The optical high-pass filter 77 is bonded to the emission surface 76 of the prism 69, and as shown in FIG. 12, the cut-off wavelength λ of the transmission wavelength characteristic of the optical low-pass filter 75 is obtained.₇₅(Here, the wavelength at which the transmittance of the optical low-pass filter 75 is 50% of the maximum transmittance is defined as the cutoff wavelength). The optical low-pass filter has a cutoff wavelength characteristic shifted to the longer wavelength side. Among the long-wavelength light images transmitted through 75, the cutoff wavelength λ₇₇A light image having a shorter wavelength (light image in the shaded area) is transmitted. The optical low-pass filter 79 is bonded to the emission surface 78 (rear surface 71) of the prism 74, and as shown in FIG. 13, the cut-off wavelength λ of the reflection wavelength characteristic of the optical low-pass filter 75.₇₅Cut-off wavelength λ shifted to shorter wavelength side₇₉Of the short-wavelength light image reflected by the optical low-pass filter 75 and having a cutoff wavelength λ₇₉A light image having a longer wavelength (light image in the shaded area) is transmitted.
[0082]
  Of course, also in this prism type bandpass filter 67, the optical path length between the lens 38 and the short wavelength side imaging device 46 and the optical path length between the lens 38 and the long wavelength side imaging device 48 are the same. Each optical path length in the prism type band pass filter 67 is set.
[0083]
  In the wavelength selection optical system 31 a, a short-wavelength light image and a long-wavelength light image selected by the liquid crystal filter 37 are output, and are collected by the lens 38 while being incident on the incident surface (front surface 70) 80. When incident, as shown in FIG. 12, by the filtering operation of the optical low-pass filter 75 and the filtering operation of the optical high-pass filter 77, the wavelength λ_aAn optical image belonging to a long wavelength region centered on the image is selected and incident on the long wavelength side image sensor 48 to generate a long wavelength side video signal and a long wavelength side video signal, and an optical low-pass filter. By the filtering operation of 75 and the filtering operation of the optical low-pass filter 79, as shown in FIG._bAn optical image belonging to a short wavelength region centering on is selected and made incident on the short wavelength side image pickup device 46 to generate a short wavelength side video signal.
[0084]
  As described above, even when the wavelength selection optical system 31a configured by the liquid crystal filter 37, the lens 38, the prism type bandpass filter 67, the short wavelength side imaging element 46, and the long wavelength side imaging element 48 is used, The short-wavelength side video signal and the long-wavelength side video signal are divided into two light images that are not inverted in the left-right direction by dividing the short-wavelength optical image and long-wavelength optical image selected by the liquid crystal filter 37 into two. And can be generated.
[0085]
    <Second Modification of Second Embodiment>
  In the first modification shown in FIG. 11, the wavelength selection optical system 31 a is configured by the liquid crystal filter 37, the lens 38, the prism type band pass filter 67, the short wavelength side imaging element 46, and the long wavelength side imaging element 48. As shown in FIG. 14, the liquid crystal filter 37, the lens 38, the prism-type low-pass filter 81, the optical low-pass filter 82, the optical high-pass filter 83, and the short wavelength side imaging device are configured. 46 and the long wavelength side imaging device 48 constitute a wavelength selection optical system 31b, and the wavelength selection optical system 31b is used to discriminate the wavelength of the optical image from the subject, and the short wavelength side video signal and the long wavelength side To generate video signals.good.
[0086]
  In this case, the prism type low-pass filter 81 includes a prism 85, a prism 90, and an optical low-pass filter 91. The prism 85 is a prism whose front surface 84 side is cut at 45 degrees. The prism 90 is a parallelogram prism that is cut so that the angle formed by the front surface 86 (rear surface 87) and the inclined surfaces 88 and 89 is 45 degrees and 135 degrees. The optical low-pass filter 91 is disposed on the joint surface between the inclined surface 89 of the prism 90 and the front surface 84 of the prism 85, and has the same low-pass characteristics as the optical low-pass filter 75 shown in FIG. The optical image belonging to the region is transmitted and the optical image belonging to the short wavelength region is reflected.
[0087]
  In this prism type low-pass filter 81, when a light image in a short wavelength region and a light image in a long wavelength region are incident on the incident surface (front surface 86) 92 from the lens 38, The light image is transmitted from the output surface 93 and incident on the optical high-pass filter 83. The optical low-pass filter 91 reflects the light image on the short wavelength side, and then totally reflects the light image. The light is reflected by the surface 94, is emitted from the emission surface 95, and is incident on the optical low-pass filter 82.
[0088]
  The optical low-pass filter 82 is configured by a filter plate having the same low-pass characteristics (low-pass characteristics shown in FIG. 13) as the optical low-pass filter 79 shown in FIG. After the optical image on the short wavelength side, as shown in FIG._bA short-wavelength-side optical image centering on is selected and made incident on the short-wavelength-side imaging device 46 to generate a short-wavelength-side video signal.
[0089]
  The optical high-pass filter 83 is configured by a filter plate having the same high-pass characteristics (high-pass characteristics shown in FIG. 12) as the optical high-pass filter 77 shown in FIG. As shown in FIG. 12, among the long-wavelength light images emitted from the wavelength λ,_aA long-wavelength side image signal is generated by selecting an optical image on the long-wavelength side centering on, and making it incident on the long-wavelength-side image sensor 48.
[0090]
  As described above, the liquid crystal filter 37, the lens 38, the prism-type low-pass filter 81, the optical low-pass filter 82, the optical high-pass filter 83, the short wavelength side image sensor 46, and the long wavelength side image sensor 48. Even when the configured wavelength selection optical system 31b is used, it is possible to discriminate the wavelength of an optical image from a subject and generate a short wavelength side video signal and a long wavelength side video signal.
[0091]
    <Third Modification of Second Embodiment>
  In the second modification shown in FIG. 14, the liquid crystal filter 37, the lens 38, the prism type low-pass filter 81, the optical low-pass filter 82, the optical high-pass filter 83, the short wavelength side image sensor 46, Although the wavelength selection optical system 31b is constituted by the long wavelength side image pickup device 48, as shown in FIG. 15, a liquid crystal filter 37, a lens 38, a prism type low pass filter 96, and two optical bands. The path filters 97 and 98, the short wavelength side imaging device 46, and the long wavelength side imaging device 48 constitute a wavelength selection optical system 31c, and the wavelength selection optical system 31c is used to change the wavelength of an optical image from the subject. Discriminating and generating a short wavelength side video signal and a long wavelength side video signalgood.
[0092]
  In this case, the prism type low-pass filter 96 includes a prism 100, a prism 105, and an optical low-pass filter 106. The prism 100 is a prism whose front surface 99 side is cut at 45 degrees. The prism 105 is a parallelogram prism that is cut so that the angle between the front surface 101 (rear surface 102) and the inclined surfaces 103 and 104 is 45 degrees and 135 degrees. The optical low-pass filter 96 is disposed on the joint surface between the inclined surface 104 of the prism 105 and the front surface 99 of the prism 100, and has the same low-pass characteristics as the optical low-pass filter 91 shown in FIG. The optical image belonging to the region is transmitted and the optical image belonging to the short wavelength region is reflected. The prism-type low-pass filter 96 belongs to the long-wavelength region by the filtering operation of the optical low-pass filter 106 when a short-wavelength light image and a long-wavelength light image are incident on the incident surface 107 from the lens 38. The optical image is transmitted, is output from the output surface 108, is incident on the optical bandpass filter 98, and the optical lowpass filter 106 reflects the optical image on the short wavelength side, which is then totally reflected. The light is reflected by the surface 109, is emitted from the emission surface 110, and is incident on the optical bandpass filter 97.
[0093]
  As shown in FIG. 16, the optical bandpass filter 97 has a wavelength λ from the short wavelength side optical image selected by the lowpass filtering characteristic of the optical lowpass filter 106._dIs a filter plate having a bandpass characteristic for extracting light of a wavelength included in a predetermined region, and among the short-wavelength side light images emitted from the emission surface 110 of the prism type low-pass filter 96, As shown in FIG. 16, the wavelength λ_dAn optical image in a predetermined wavelength region centering on is selected and made incident on the short-wavelength imaging device 46 to generate a short-wavelength video signal.
[0094]
  Further, as shown in FIG. 17, the optical band-pass filter 98 has a wavelength λ from the long-wavelength optical image selected by the low-pass filtering characteristic of the optical low-pass filter 106._cIs a filter plate having a bandpass characteristic for extracting light having a wavelength included in a predetermined region, and a long-wavelength optical image emitted from the emission surface 108 of the prism type low-pass filter 96, a long wavelength In the side optical image, as shown in FIG._cAn optical image in a predetermined wavelength region centering on is selected and made incident on the long-wavelength imaging device 48 to generate a long-wavelength video signal.
[0095]
  Thus, wavelength selection is performed by the liquid crystal filter 37, the lens 38, the prism-type low-pass filter 96, the two optical band-pass filters 97 and 98, the short-wavelength side image sensor 46, and the long-wavelength side image sensor 48. Even if the optical system 31c is configured and the wavelength selection optical system 31c is used, it is possible to discriminate the wavelength of an optical image from a subject and generate a short wavelength side video signal and a long wavelength side video signal.
[0096]
    <Fourth Modification of Second Embodiment>
  Further, in the wavelength selection type liquid crystal camera device 30 shown in FIG. 8, the liquid crystal filter 37, the lens 38, the beam splitter 44, the two optical bandpass filters 45 and 47, the short wavelength side imaging device 46, and the long The wavelength selection optical system 31 constituted by the wavelength side imaging device 48 is used, but the wavelength selection is made by removing the two optical bandpass filters 45 and 47 constituting the wavelength selection optical system 31. An optical system may be used.
[0097]
  Further, in the wavelength selection type liquid crystal camera device 30 shown in FIG. 8, the liquid crystal filter 37, the lens 38, the beam splitter 44, the two optical bandpass filters 45 and 47, the short wavelength side imaging device 46, and the long A wavelength selection optical system 31 constituted by the wavelength side image pickup device 48 is used. Instead of the beam splitter 44 constituting the wavelength selection optical system 31, a prism type low-pass filter shown in FIG. A wavelength selection optical system in which 81 is provided and the two optical bandpass filters 45 and 47 are removed may be used.
[0098]
    <Fifth Modification of Second Embodiment>
  Further, in the wavelength selection type liquid crystal camera device 30 shown in FIG. 8, when no alternating voltage is applied, a light beam that senses only the ordinary light refractive index of the liquid crystal is selected, and when the alternating voltage is applied, the ordinary light refractive index. And the extraordinary refractive index are selected so that each light beam is incident on the short-wavelength side image sensor 46 and the long-wavelength side image sensor 48. 38, or in front of the short-wavelength side image pickup element 46 and the long-wavelength side image pickup element 48, a polarizing film (or a polarizing plate) is disposed, and the light beam that senses only ordinary light refractive index is removed by this polarizing film. The light may be incident on the short wavelength side image sensor 46 and the long wavelength side image sensor 48.
[0099]
  Even in this case, like the wavelength selective liquid crystal camera device 30 shown in FIG. 8, it is possible to detect an oil film, an organic film, etc. on the water surface as an image with high contrast, which has heretofore been difficult to detect.it can.
[0100]
    <Sixth Modification of Second Embodiment>
  Further, in the wavelength selective liquid crystal camera device 30 shown in FIG. 8, the wavelength selective optical system 31, the short wavelength side image processing unit 32, the short wavelength side difference image extracting unit 33, and the long wavelength side image processing unit 34 are provided. The long wavelength side difference image extraction unit 35 and the video synthesis unit 36 are included in one housing to constitute a camera device. However, all of the video synthesis unit 36 and the short wavelength side difference image extraction unit 33, all of the long wavelength side difference image extraction unit 35, all or part of the short wavelength side image processing unit 32, and all or part of the long wavelength side image processing unit 34 are separated from the camera device. You may do it.
[0101]
  By doing so, the camera device portion can be reduced in size and weight, and handling and operation of the camera device can be facilitated.
[0102]
    << Description of the Third Embodiment of the Invention >>
    <Basic description of the third embodiment>
  FIG. 18 shows a wavelength selective liquid crystal camera device according to the present invention.3rd Embodiment is shownIt is a block diagram. In this figure, in order to simplify the description, parts that are not related to the description of the present invention, such as an iris and an ND filter that attenuate the amount of incident light, components necessary for configuring the camera device, and a drive circuit. A pulse generation circuit that sends a pulse signal to a video processing circuit, a contour compensation circuit that emphasizes the contour of a video, a power supply circuit, and the like are omitted.
[0103]
  The wavelength selection type liquid crystal camera device 111 shown in this figure includes a full color wavelength selection optical system 112, an R color image processing unit 113, and an R color difference image extraction unit 114. The full-color wavelength selection optical system 112 captures an optical image from a subject and separates it into three primary colors of R, G, and B, and for each of R, G, and B, a short wavelength optical image and a long wavelength optical image. Are extracted, photoelectrically converted, and a short wavelength video signal (R color short wavelength video signal) for the R light image, a long wavelength video signal (R color long wavelength video signal), and a short for the G light image are extracted. Wavelength range video signal (G color short wavelength range video signal), long wavelength range video signal (G color long wavelength range video signal), short wavelength range video signal for B optical image (B color short wavelength range video signal) Then, a long wavelength video signal (B color long wavelength video signal) is sequentially generated. The R color image processing unit 113 performs image processing on the R color short wavelength region video signal and the R color long wavelength region video signal sequentially output from the full color wavelength selection optical system 112 and digitizes the R color short wavelength region video signal. , R color long wavelength region video signals are sequentially generated. The R color difference image extraction unit 114 stores at least one of the R color short wavelength region video signal and the R color long wavelength region image signal output from the R color image processing unit 113 in units of frames, and stores these R color short image signals. Based on the difference between the wavelength band video signal and the R color long wavelength band video signal, an R color video signal with a high contrast such as an oil film image or an organic film image floating on the sea surface or water surface is generated.
[0104]
  Further, the wavelength selection type liquid crystal camera device 111 includes a G color image processing unit 115, a G color difference image extraction unit 116, a B color image processing unit 117, a B color difference image extraction unit 118, and an encoder circuit 119. Yes. The G color image processing unit 115 is a G color short wavelength region video signal that is sequentially output from the full color wavelength selection optical system 112, a G color short wavelength region image signal obtained by digitizing the G color long wavelength region image signal, G color long wavelength region video signals are sequentially generated. The G color difference image extraction unit 116 stores at least one of the G color short wavelength region video signal and the G color long wavelength region video signal output from the G color image processing unit 115 in units of frames, Based on the difference between the wavelength band video signal and the G color long wavelength band video signal, a G color video signal having a high contrast such as an oil film image or an organic film image floating on the sea surface or the water surface is generated. The B color image processing unit 117 is a B color short wavelength region video signal sequentially output from the full color wavelength selection optical system 112, a B color short wavelength region image signal obtained by digitizing the B color long wavelength region image signal, B color long wavelength region video signals are sequentially generated. The B color difference image extraction unit 118 stores at least one of the B color short wavelength region video signal and the B color long wavelength region image signal output from the B color image processing unit 117 in units of frames, Based on the difference between the wavelength band video signal and the B color long wavelength band video signal, a B color video signal having a high contrast such as an oil film image or an organic film image floating on the sea surface or the water surface is generated. The encoder circuit 119 combines the R color video signal, the G color video signal, and the B color video signal output from the R color difference image extraction unit 114, the G color difference image extraction unit 116, and the B color difference image extraction unit 118, respectively. Generate a color television signal.
[0105]
  As with the liquid crystal filters 5 and 37 shown in FIGS. 1 and 8, the full color wavelength selection optical system 112 includes a liquid crystal filter 120, a lens 121, a dichroic prism 123, an R color image sensor 124, and a G color image sensor 125. And a B-color image pickup device 126, which captures a light image (white light image) from a subject, and according to an input AC voltage, a short-wavelength light image constituting the light image; While sequentially cyclically extracting the long-wavelength light image constituting the light image, the short-wavelength light image and the long-wavelength light image are converted into an R-color light image, a G-color light image, After being separated into the B color light image, the R color light image, the G color light image, and the B color light image are respectively photoelectrically converted, and the R color short wavelength region video signal obtained thereby, The color long wavelength band video signal is sequentially supplied to the R color image processing unit 113, and the G color The wavelength band video signal and the G color long wavelength band video signal are sequentially supplied to the G color image processing unit 115, and the B color short wavelength band video signal and the B color long wavelength band video signal are further supplied to the B color image processing unit. 117 are sequentially supplied. The liquid crystal filter 120 captures a light image (white light image) from the subject, and extracts a short-wavelength light image and a long-wavelength light image according to the input AC voltage. The lens 121 condenses the short-wavelength light image and the long-wavelength light image extracted by the liquid crystal filter 120, and forms a rearward image by a predetermined distance. The dichroic prism 123 separates the short-wavelength light image and the long-wavelength light image collected by the lens 121 into an R-color light image, a G-color light image, and a B-color light image. The R-color image pickup device 124 is a solid-state image pickup device using silicon, such as CCD, MOS, CPD, SIT, AMI, or the like, or a solid-state image pickup device using a material having high sensitivity in the infrared region such as GaAs, InGaAs, or amorphous selenium. R or the like emitted from the dichroic prism 123, such as a solid-state imaging device using a material exhibiting high sensitivity in ultraviolet light or short-wavelength visible light, or an imaging tube such as planbicon, sachicon, vidicon, carnicon, or harpicon. An optical image of a short wavelength region and an optical image of a long wavelength region are photoelectrically / electrically converted to sequentially generate an R color short wavelength region video signal and an R color long wavelength region image signal in order. The G-color image sensor 125 is configured in the same manner as the R-color image sensor 124, and optically / electrically converts a G-color short-wavelength light image and a long-wavelength light image emitted from the dichroic prism 123 to obtain a G-color image. A short wavelength video signal and a G color long wavelength video signal are sequentially generated in a cyclic manner. The B-color image pickup device 126 is configured in the same manner as the R-color image pickup device 124 and the G-color image pickup device 125. The B-color image pickup device 126 outputs a B-color short-wavelength light image and a long-wavelength light image emitted from the dichroic prism 123. Electric conversion is performed to sequentially generate a B color short wavelength region video signal and a B color long wavelength region image signal sequentially.
[0106]
  As shown in FIG. 19, the R color image processing unit 113 includes a head amplifier circuit 127, a video processing circuit 128, and an A / D conversion circuit 129, and an R output from the full color wavelength selection optical system 112. Pre-amplification processing, transmission region compensation processing of the liquid crystal filter 120, transmittance compensation processing of the liquid crystal filter 120, etc. are performed on the color short wavelength region video signal and the R color long wavelength region video signal, and the R color obtained thereby The short wavelength region video signal and the R color long wavelength region image signal are digitized and supplied to the R color difference image extraction unit 114. The head amplifier circuit 127 amplifies the R color short wavelength region video signal and the R color long wavelength region image signal sequentially output from the full color wavelength selection optical system 112 at a constant amplification factor. The video processing circuit 128 performs preset image processing on the R color short wavelength region video signal and the R color long wavelength region video signal sequentially output from the head amplifier circuit 127, for example, transmission region compensation of the liquid crystal filter 120, The transmittance of the liquid crystal filter 120 is compensated. The A / D conversion circuit 129 performs A / D conversion on the R color short wavelength region video signal and the R color long wavelength region video signal sequentially output from the video processing circuit 128, thereby digitizing the R color short wavelength region. An image signal and an R color long wavelength region image signal are generated.
[0107]
  The R color difference image extraction unit 114 includes a frame memory circuit 130, a difference circuit 131, an absolute value circuit 132, a D / A conversion circuit 133, and an amplifier circuit 134. Based on the input vertical synchronization signal, When the digitized R color short wavelength region video signal is output from the R color image processing unit 113, the R color short wavelength region video signal is captured and stored, and also digitized from the R color image processing unit 113. Is output, the R color long wavelength region video signal and the stored R color short wavelength region video signal are compared in pixel units, and the level difference between the pixels of the same spatial coordinates is calculated. The R color video signal indicating the difference between the R color short wavelength region video signal and the R color long wavelength region image signal thus obtained (for example, the contrast of the image of the oil film floating on the water surface or the image of the organic film is increased). R color image ) And analogs of the supply to the encoder circuit 119. The frame memory circuit 130 sets in advance one of the digitized R color short wavelength region video signal and R color long wavelength region video signal output from the R color image processing unit 113 based on the input vertical synchronization signal. When an R color long wavelength region video signal is output from the R color image processing unit 113 after capturing and storing a video signal in the wavelength region, for example, an R color short wavelength region video signal in units of frames, Synchronously, the stored R color short wavelength region video signal is output. The difference circuit 131 generates an R color short wavelength region video signal output from the frame memory circuit 130 and an R color long wavelength region image signal output from the R color image processing unit 113 based on the input vertical synchronization signal. Comparison is made on a pixel-by-pixel basis, and a level difference between pixels having the same spatial coordinates is calculated to generate an R-color video signal indicating the difference between the R-color short wavelength region video signal and the R-color long wavelength region video signal. The counter circuit 132 calculates the absolute value of the R color video signal output from the difference circuit 131. The D / A conversion circuit 133 converts the R color video signal in the digital signal format output from the absolute value circuit 132 into an R color video signal in the analog signal format. The amplification circuit 134 amplifies the R color video signal output from the D / A conversion circuit 133.
[0108]
  Similarly to the R color image processing unit 115, the G color image processing unit 115 includes a head amplifier circuit 127, a video processing circuit 128, and an A / D conversion circuit 129, as shown in FIG. Pre-amplification processing, transmission region compensation processing of the liquid crystal filter 120, and transmittance compensation processing of the liquid crystal filter 120 for the G color short wavelength region video signal and the G color long wavelength region image signal output from the full color wavelength selection optical system 112 The G color short wavelength region video signal and the G color long wavelength region image signal thus obtained are digitized and supplied to the G color difference image extraction unit 116.
[0109]
  Similar to the R color difference image extraction unit 114, the G color difference image extraction unit 116 includes a frame memory circuit 130, a difference circuit 131, an absolute value circuit 132, a D / A conversion circuit 133, and an amplification circuit 134. When the digitized G color short wavelength region video signal is output from the G color image processing unit 115 based on the input vertical synchronization signal, it is captured and stored, and from the G color image processing unit 115 When the digitized G color long wavelength region video signal is output, the G color long wavelength region video signal is compared with the stored G color short wavelength region image signal in units of pixels, and the same spatial coordinates The G-color video signal indicating the difference between the G-color short wavelength region video signal and the G-color long wavelength region image signal obtained by calculating the level difference between the respective pixels (for example, the image of the oil film floating on the water surface) Or an organic film Higher the G color video signal contrast) to analog form and supplies the encoder circuit 119.
[0110]
  Similarly to the R color image processing unit 113 and the G color image processing unit 115, the B color image processing unit 117 also has a head amplifier circuit 143, a video processing circuit 144, and an A / D conversion circuit as shown in FIG. 145, pre-amplification processing, transmission region compensation processing of the liquid crystal filter 120, and liquid crystal filter 120 for the B color short wavelength region video signal and B color long wavelength region image signal output from the full color wavelength selection optical system 112 The transmittance compensation process of the filter 120 is performed, and the B color short wavelength region video signal and the B color long wavelength region image signal obtained thereby are digitized and supplied to the B color difference image extraction unit 118.
[0111]
  As with the R color difference image extraction unit 114 and the G color difference image extraction unit 116, the B color difference image extraction unit 118 includes a frame memory circuit 146, a difference circuit 147, an absolute value circuit 148, a D / A conversion circuit 149, When the digitized B color short wavelength band video signal is output from the B color image processing unit 117 based on the input vertical synchronization signal, it is captured and stored. When the digitized B color long wavelength range video signal is output from the B color image processing unit 117, the B color long wavelength range video signal and the stored B color short wavelength range video signal are converted into pixel units. The B color video signal (for example, indicating the difference between the B color short wavelength region video signal and the B color long wavelength region video signal obtained by calculating the level difference between the pixels having the same spatial coordinates. Floating on the water The higher the B color video signal) contrast, such as images of oil film video and organic film into analog, and supplies the encoder circuit 119.
[0112]
  The encoder circuit 119 includes an R color video signal output from the R color difference image extraction unit 114, a G color video signal output from the G color difference image extraction unit 116, and a B color video output from the B color difference image extraction unit 118. The signal is taken in and synthesized by a preset synthesis method to generate a synthesized color television signal, which is supplied to a display device or the like, and an oil film image or the like is imaged.
[0113]
  As described above, in this embodiment, the full-color wavelength selection optical system 112 shoots the sea surface where the oil film is floated, and the short wavelength image signal and the long wavelength image for each of R, G, and B. The R color image processing unit 113, the G color image processing unit 115, and the B color image processing unit 117 sequentially generate a signal and a short wavelength video signal and a long wavelength video for each of R, G, and B. The signal is image-processed to generate a digitized short-wavelength video signal and a long-wavelength video signal, and then an R color difference image extraction unit 114, a G color difference image extraction unit 116, and a B color difference image extraction unit. 118, for each of R, G, and B, the difference between the short wavelength video signal and the long wavelength video signal is extracted to increase the contrast of the oil film image or the organic film image floating on the water surface. Generated video signals for each of R, G, and B Since the resulting composite color TV signal is supplied to the display device, oil film and organic film on the water surface can be detected as a full-color image with high contrast regardless of the water surface condition. Can do.
[0114]
  Conventionally, even when searching for a distressed site by visual observation from a helicopter or an aircraft, when it is difficult to find an oil film, for example, when the reflected light from the sea surface is strong (backlit state), in the case of rainy weather, Even if it is high, regardless of the state of the sea surface, when an oil film such as a damaged aircraft or ship floats on the sea surface, it is possible to reliably detect this and find the disaster site.
[0115]
  In this embodiment, the R color output from the R color difference image extraction unit 114, the G color difference image extraction unit 116, and the B color difference image extraction unit 118 only when there is an oil film or an organic film on the photographed sea surface. Since the video signal, the G color video signal, and the B color video signal are set to values other than zero, the composite color television signal output from the encoder circuit 119 is guided to a determination circuit (not shown) and set in advance. By simply determining whether or not the threshold value is exceeded, the search for the distress site can be easily automated. Accordingly, a plurality of wavelength selective liquid crystal camera devices 111 shown in FIG. 18 are installed in a helicopter, an aircraft, etc., and each wavelength selective liquid crystal camera device 111 searches for all directions at the same time and automatically determines the presence or absence of an oil film or the like. Compared with the case of conventional visual inspection, the search efficiency can be greatly improved and quick disaster relief can be performed.it can.
[0116]
  In addition, by combining the wavelength selective liquid crystal camera device 111 shown in FIG. 18 and a GPS (Global Positioning System) device, the position of the oil film can be determined instantaneously, thereby further finding the location of the distress, In addition to speeding up, it is possible to easily map the situation of oil spills such as tankers in real time.
[0117]
    <First Modification of Third Embodiment>
  Further, in the wavelength selective liquid crystal camera device 111 shown in FIG. 18, the liquid crystal filter 120 alternately extracts the short wavelength light image and the long wavelength light image included in the light image from the subject, The dichroic prism 123 separates the short-wavelength light image and the long-wavelength light image into R color, G color, and B color, and the R image sensor 124, the G image sensor 125, and the B image sensor 126 are separated. Each of the optical images is formed above, but an optical bandpass filter 151 is disposed in front of the dichroic prism 123 as in the full-color wavelength selection optical system 112a shown in FIG. Thus, after narrowing the wavelength range by band-pass filtering the short-wavelength light image and the long-wavelength light image selected by the liquid crystal filter 120, the dichroic The rhythm 123, R color, G color, separated into color B, the R-color image pickup device 124, on the G color image pickup device 125, even if each on the B color image pickup device 126 such that imaginggood.
[0118]
  However, it is necessary to make the full width half maximum of the optical bandpass filter 151 wider than the full width at half maximum of the light image incident on the R color image sensor 124, the G color image sensor 125, and the B color image sensor 126. It is.
[0119]
  Even in this case, similar to the wavelength selective liquid crystal camera device 111 shown in FIG. 18, it is possible to detect an oil film or an organic film on the water surface, which has been difficult to detect conventionally, as a high-contrast full-color image.
[0120]
  In this first modification, the optical bandpass filter 151 is arranged in front of the dichroic prism 123. However, if it is in front of the R imaging element 124, the G imaging element 125, and the B imaging element 126, One optical bandpass filter may be disposed before the liquid crystal filter 120, or three optical bandpass filters may be disposed after the dichroic prism 123.
[0121]
  As described above, the same effect as that of the first modification can be obtained no matter where the optical band-pass filter is disposed before the R imaging element 124, the G imaging element 125, and the B imaging element 126.
[0122]
    <Second Modification of Third Embodiment>
  In addition, in the wavelength selection type liquid crystal camera device 111 shown in FIG. 18, R imaging is performed for a light beam that feels only the ordinary light refractive index of the liquid crystal and a light beam that feels both the ordinary light refractive index and the extraordinary light refractive index when a voltage is applied. The light is incident on the element 124, the G image sensor 125, and the B image sensor 126, but a polarizing film (or a polarizing plate) is placed behind the liquid crystal filter 120 as in the full color wavelength selection optical system 112b shown in FIG. 152, and the polarizing film 152 removes the light beam that senses only the ordinary light refractive index and makes it incident on the R imaging device 124, the G imaging device 125, and the B imaging device 126.good.
[0123]
  Even in this case, similar to the wavelength selective liquid crystal camera device 111 shown in FIG. 18, it is possible to detect an oil film, an organic film, etc. on the water surface, which has heretofore been difficult to detect, as a high-contrast full-color image.
[0124]
  In the second modification, the polarizing film 152 is disposed between the liquid crystal filter 120 and the lens 121, but in front of the R imaging element 124, the G imaging element 125, and the B imaging element 126. If necessary, a polarizing film may be disposed in front of the liquid crystal filter 120, behind the lens 121, or on each exit surface of the dichroic prism 123.
[0125]
    <Third Modification of Third Embodiment>
  Further, in the wavelength selection type liquid crystal camera device 111 shown in FIG. 18, the full color wavelength selection type optical system 112, the R color image processing unit 113, the R color difference image extraction unit 114, the G color image processing unit 115, and the G color difference. An image extraction unit 116, a B color image processing unit 117, a B color difference image extraction unit 118, and an encoder circuit 119 are included in one housing to constitute a camera device. All of the R color difference image extracting unit 114, all of the G color difference image extracting unit 116, all of the B color difference image extracting unit 118, all or part of the R color image processing unit 113, and the G color image processing unit. All or part of 115 and all or part of the B-color image processing unit 117 may be separated from the camera device.
[0126]
  By doing so, the camera device portion can be reduced in size and weight, and handling and operation of the camera device can be facilitated.
[0127]
    << Description of the liquid crystal used in the first to third embodiments >>
  In the first to third embodiments described above, the liquid crystal filters 5, 37, and 120 can be changed from one transmission characteristic to the other according to the presence or absence of an alternating voltage, such as a ferroelectric liquid crystal or an antiferroelectric liquid crystal. When using a liquid crystal filter having an excellent response speed that can be quickly switched to the transmission characteristics, there is no problem.
[0128]
  Further, as the liquid crystal filters 5, 37, 120, liquid crystal filters such as nematic liquid crystals and cholesteric liquid crystals, which cannot quickly switch from one transmission characteristic to the other transmission characteristic depending on the presence or absence of an alternating voltage, are used. In such a case, since the transient operation must be taken into consideration, when the liquid crystal having such characteristics is used for a display device or the like, it becomes a big problem, but the wavelength selective liquid crystal camera device 1 according to the present invention, 30 and 111 are hardly a problem. Hereinafter, this reason will be described in detail.
[0129]
  First, each of the liquid crystal filters 5, 37, 120, for example, each dielectric multilayer film 10, 13 constituting the liquid crystal filter 5 has a power reflectance of “R”, and light incident perpendicularly to the liquid crystal layer 14 is liquid crystal layer Assuming that the amount of phase change when passing through the inside 14 is “δ” and the incident light is linearly polarized, the liquid crystal filter 5, the dielectric multilayer films 10 and 13, etc. Is ignored, the transmittance T of the liquid crystal filter 5 can be expressed by the following equation.
[0130]
[Equation 7]
    T = [1 + 4Rsin²(Δ / 2) / (1-R)²]^-1    ... (7)
  When the wavelength of light in vacuum is “λ”, the refractive index of the liquid crystal constituting the liquid crystal layer 14 is “n”, and the thickness is “D”, the phase change amount δ is expressed by the following equation: Can be.
[0131]
  δ = 4πnD / λ (8)
[0132]
  Here, assuming that “R = 0.7” and calculating the relationship between the transmittance T and the wavelength λ from the equations (7) and (8), the graph shown in FIG. 24 is obtained, which is apparent from this graph. Thus, even if the refractive index n of the liquid crystal constituting the liquid crystal layer 14 changes, only the center wavelength (the wavelength at which the transmittance T of the liquid crystal filter 5 becomes maximum) is shifted, and the transmittance curve does not change. .
[0133]
  Thus, when the response of the liquid crystal is slow, the wavelength filter 5 operates to settle at a certain wavelength while selecting various wavelengths. At this time, as shown in Table 1, the refractive index of water has wavelength dependency. However, since the refractive index of freshwater or seawater hardly changes with the wavelength change caused by the liquid crystal, even if the liquid crystal filter 5 operates transiently, if there is no oil film on the sea surface, the brightness of the water surface is constant. Thus, there is no signal level difference between the two frames, and an image indicating zero is displayed on the display device.
[0134]
  On the other hand, as shown in FIG. 5, when there is an oil film on the sea surface, even if the wavelength changes slightly, the reflected light intensity of the oil film changes greatly, so that the liquid crystal filter 5 operates transiently. Even if there is a signal level difference between the two frames,
An oil film image is displayed on the display device.
[0135]
  However, considering the transient characteristics, the two light quantities transmitted through the liquid crystal filter 5 (the total value of the thick solid line and the total value of the thin solid line) do not always coincide with each other. The object is photographed, and the transmittance characteristic and reflectance characteristic of the video processing circuit 16 constituting the image processing unit 3 are adjusted (setup adjustment) so that the photoelectric change signals for the two different wavelengths match. It is necessary to keep.
[0136]
  Strictly speaking, a slight transient effect appears in the ferroelectric liquid crystal or the like, so it is better to perform setup adjustment by photographing a blank sheet or the like as in the case of the nematic liquid crystal.
[0137]
  Moreover, although it is a rare case, when the sea surface with an oil film is image | photographed, the light from the specific incident angle is inject | emitted, the light quantity of the light image of the short wavelength region output from the liquid crystal filter 5, and a long wavelength region However, even in such a special case, the wavelength-selective liquid crystal camera device 1 has various incident angles φ.₁Therefore, the presence of the oil film is not lost.
[0138]
  Similarly, as shown in FIG. 25, the sea surface 153 constantly fluctuates due to waves, winds, and the like, and light images from various incident angles are mounted on the helicopter 154, compared to the incident angle when the sea surface 153 is in a mirror state. Since it is taken into the wavelength selective liquid crystal camera device 1, even if the reflectance becomes the same level at a specific incident angle, the reflectance becomes a different level at other incident angles, and the oil film is hardly lost.
[0139]
  In particular, as in the case of the wavelength selection type liquid crystal camera device 30 shown in FIG. 8 or the like, when the light image is divided into the short wavelength side optical image and the long wavelength side optical image, or the wavelength selection type liquid crystal camera device shown in FIG. When a plurality of video signals having different wavelengths are created, such as when the image is divided into an R color light image, a G color light image, and a B color video signal, such as 111, Since the oil film or the organic film can be detected in such a wavelength region, the oil film or the organic film can be reliably detected so that the oil film or the like is not lost.
[0140]
    << Description of Oil Film Detection Sensitivity in First to Third Embodiments >>
  Next, the image sensor 7, the short wavelength side image sensor 46, and the long wavelength side image sensor when the oil film floating on the sea surface is detected using each of the wavelength selective liquid crystal camera devices 1, 30, and 111 described above. 48, the relationship between the resolution of the R color image sensor 124, the G color image sensor 125, the B color image sensor 126, etc., and the oil film detection sensitivity will be described.
[0141]
    <Capability of exploration in a stationary state>
  First, each pixel (pixel) which is the minimum detection unit of the image sensor 7 used in each of the wavelength selective liquid crystal camera devices 1, 30 and 111 described above, for example, the wavelength selective liquid crystal camera device 1 shown in FIG. 1 is large. Or when the shooting distance is short, the incident angle φ₁A plurality of light beams having different values are incident, and the output of each pixel is a value obtained by adding the luminance of each light beam.
[0142]
  At this time, the incident angle φ for each light beam₁However, if the angle difference is large, the wavelength dependency of the luminance obtained from the reflectance is relaxed, and the oil film detection sensitivity may be lowered. This point will be described in detail.
[0143]
  Now, as the imaging device 7 used in the wavelength selective liquid crystal camera device 1, the number of vertical pixels is set to “450”, the number of horizontal pixels is set to about “600”, and the light receiving portion of the pixel is formed in a square shape. As shown in FIG. 26, the wavelength selective liquid crystal camera device 1 is attached to the helicopter 155, and the image capture angle of the wavelength selective liquid crystal camera device 1 (wavelength selective liquid crystal camera) is assumed. The lens 6 is adjusted so that the maximum angle formed by the optical axis 156 of the apparatus 1 and the light beams 157 and 158 from the subject becomes a predetermined value, for example, “± 25 degrees”, and the wavelength selective liquid crystal camera apparatus 1 The helicopter is adjusted so that the height from the sea surface 159 is 300 to 1000 m in a state where the photographing direction of the wavelength selective liquid crystal camera device 1 is adjusted so that the optical axis 156 is orthogonal to the sea surface 159. Skip 55, consider the case to probe oil film is floating on the sea surface 159.
[0144]
  In this case, when the helicopter 155 takes an image of the sea surface 159 with the wavelength selective liquid crystal camera device 1 while flying over the sea surface 159 from 300 to 1000 m, for example, 800 m above, for example, the wavelength selective liquid crystal camera device 1 as shown in FIG. Since the image pickup device 7 of FIG. 1 can search a rectangular area ABCD (about 597 m × about 448 m) inscribed in a circle having a diameter of “746 m” on the sea surface 159 during one frame, "About 1m²The light beam from the portion “” is incident on one pixel constituting the image sensor 7.
[0145]
  This area isundulationCompared with the fluctuation of the sea level 159 due to the above, the value is sufficiently small, so that only the wavelength selection type liquid crystal camera device 1 according to the present invention is used, and a normal search method that has been conventionally used can be sufficiently detected. With sensitivity, an oil film floating on the sea surface 159 can be detected. Further, if an image sensor used in a high-resolution television camera device such as a high-definition television camera device is used, the minimum area S that can be disassembled is set to “0.2 m”.²", The exploration ability can be further improved.
[0146]
    <Exploration capability and range when moving>
  In addition, when the oil film floating on the sea surface 159 is searched while moving the helicopter 155 in order to widen the search range, the helicopter 155 can be detected by the flight of the helicopter 155 in order to detect the minimum resolvable area S. The speed V (km / h) is preferably set to the following value.
[0147]
[Equation 8]
    S^0.5≦ (V × 10³) / (3.6 × 10³× 30) (9)
  Thus, even if the flight speed V (km / h) of the helicopter 155 is regulated, when the flight speed V of the helicopter 155 is about 108 km / h, the exploration area S per pixel constituting the image sensor 7 is S ≒ 1m²This ensures “64.8 km per hour while ensuring sufficient resolution during oil film detection.²(108 × 0.6km²) "" Wide range can be searched.
[0148]
    <Exploration capability and exploration range in high-speed movement>
  Further, in this way, in the method of exploring while moving, since the continuous shooting method is used as the shooting method, it is possible to change the image only in the upper and lower two pixel columns between adjacent TV frames, This is sufficient when visually observing the image of the video signal to detect an oil film or the like, but in the wavelength selective liquid crystal camera device 1 according to the present invention, by providing a determination circuit in the next stage device, If shooting is performed at a distance comparable to the number of vertical pixels of the image sensor 7 such as a CCD, the flight speed of the helicopter 155 or the like for exploration can be further increased, thereby searching for a wider range. be able to.
[0149]
  However, in the case of shooting by such a method, an optical shutter is provided in front of the image sensor 7, and this optical shutter is operated so that light from a sea surface area having a spatial resolution or less can be input to each pixel. Since it is necessary, it is desirable that the opening time t of the optical shutter and the flight speed V (km / h) of the helicopter 155 or the like that performs the search satisfy the following equation.
[0150]
[Equation 9]
    S^0.5≦ (V × 10³× t) / (3.6 × 10³(10)
  Thus, when the opening time t of the optical shutter provided in the wavelength selective liquid crystal camera device 1 mounted on the helicopter 155 is “t = 5 (milliseconds)”, “V ≦ 720 (km / h)” is set. About 6.7 times (720 × 0.6 = 432 km) compared to the previous example²Can be expanded toit can.
[0151]
  Further, if a plurality of wavelength selective liquid crystal camera devices 1 are mounted on one helicopter 155 or an aircraft, and the shooting directions of the respective wavelength selective liquid crystal camera devices 1 are different from each other, and different directions are searched, Further, the exploration range can be expanded. For example, if three wavelength selection type liquid crystal camera devices 1 are used to monitor right and left and directly below, the search range per hour is about 1300 km.²This makes it possible to search all over Tokyo Bay in less than an hour.
[0152]
    <Optical shutter selection>
  For the above-described optical shutter, materials such as nematic liquid crystal, cholesteric liquid crystal, and smectic liquid crystal can be used. In this case, if a 90-degree twisted nematic liquid crystal is used as an optical shutter, white light can be modulated, and thus it can be used in a wide wavelength range, and a ferroelectric liquid crystal that is a kind of smectic liquid crystal or If antiferroelectric liquid crystal is used, optical images can be picked up at a high speed of 1 millisecond or less.it can.
[0153]
  Also, as an optical shutter, LiNbO₃LiTaO₃An electrical material such as KDP, DKDP, PZT, or GaAs can also be used. However, although it is possible to control transmission / non-transmission of a light image at a very high speed as a characteristic of each electric material, a large applied voltage is required for driving.
[0154]
  For these reasons, it is desirable to use a ferroelectric liquid crystal or an antiferroelectric liquid crystal as the optical shutter.
[0155]
【The invention's effect】
  As described above, according to the present invention, even when the reflected light from the sea surface is strong, an oil film or an organic film floating on the sea surface, or an oil film attached to the surface of a glass substrate such as a liquid crystal display or a plasma display It is possible to visualize the contamination of the organic film with a high contrast, thereby reliably finding the location of the disaster and the contamination of the glass substrate.
[0156]
  In addition, even when the reflected light from the sea surface is strong or in any state, it adheres to the surface of an oil film or organic film floating on the sea surface, or a glass substrate such as a liquid crystal display or plasma display. The oil film and organic film dirt can be imaged with high contrast, and this makes it possible to reliably find the site of distress and dirt on the glass substrate.
[0157]
  In addition, even when the reflected light from the sea surface is strong or in any state, it adheres to the surface of an oil film or organic film floating on the sea surface, or a glass substrate such as a liquid crystal display or plasma display. The oil film and organic film stains can be made into a color image with high contrast, which makes it possible to reliably find the location of the disaster and the stains on the glass substrate.
[0158]
  Also, helicopters and airplanes fly over the search area at high speed, and even if the reflected light from the sea surface is strong or in any state, the oil film floating on the sea surface, etc. An organic film or the like can be imaged with high contrast, thereby enabling to quickly and surely find a disaster site or the like.
[Brief description of the drawings]
FIG. 1 shows a wavelength selective liquid crystal camera device according to the present invention.1st Embodiment is shownIt is a block diagram.
FIG. 2 is a cross-sectional view showing a detailed configuration of the liquid crystal filter shown in FIG.
FIG. 3 is a waveform diagram showing a relationship between an AC voltage input to the liquid crystal filter shown in FIG. 1 and each frame.
4 is a block diagram illustrating detailed circuit configurations of an image processing unit and a difference image extraction unit illustrated in FIG. 1;
FIG. 5 is a graph showing an example of wavelength selection operation of the wavelength selection type liquid crystal camera device shown in FIG. 1;
6 is a block diagram showing a first modification of the wavelength selective liquid crystal camera device shown in FIG. 1. FIG.
FIG. 7 is a block diagram showing a second modification of the wavelength selective liquid crystal camera device shown in FIG.
FIG. 8 shows a wavelength selective liquid crystal camera device according to the present invention.2nd Embodiment is shownIt is a block diagram.
9 is a block diagram showing detailed circuit configurations of a short wavelength side image processing unit and a short wavelength side difference image extracting unit shown in FIG. 10;
10 is a block diagram showing detailed circuit configurations of a long wavelength side image processing unit and a long wavelength side difference image extracting unit shown in FIG. 8. FIG.
11 is a block diagram showing a wavelength selection optical system used in a first modification of the wavelength selection type liquid crystal camera device shown in FIG. 8. FIG.
12 is a graph showing an example of wavelength selection characteristics of an optical low-pass filter and an optical high-pass filter constituting the wavelength selection optical system shown in FIG.
13 is a graph showing an example of wavelength selection characteristics of optical low-pass filters constituting the wavelength selection optical system shown in FIG.
14 is a block diagram showing a wavelength selection optical system used in a second modification of the wavelength selection type liquid crystal camera device shown in FIG. 8. FIG.
15 is a block diagram showing a wavelength selection optical system used in a third modification of the wavelength selection type liquid crystal camera device shown in FIG.
16 is a graph showing an example of wavelength selection characteristics of an optical low-pass filter and one optical band-pass filter constituting the wavelength selection optical system shown in FIG.
17 is a graph showing an example of wavelength selection characteristics of the optical low-pass filter and the other optical band-pass filter that constitute the wavelength selection optical system shown in FIG. 15;
FIG. 18 shows a wavelength selective liquid crystal camera device according to the present invention.3rd Embodiment is shownIt is a block diagram.
FIG. 19 is a block diagram illustrating detailed circuit configurations of an R color image processing unit and an R color difference image extraction unit illustrated in FIG. 18;
20 is a block diagram illustrating detailed circuit configurations of a G color image processing unit and a G color difference image extraction unit illustrated in FIG. 18;
FIG. 21 is a block diagram illustrating detailed circuit configurations of a B color image processing unit and a B color difference image extraction unit illustrated in FIG. 18;
22 is a block diagram showing a full-color wavelength selection optical system used in a first modification of the wavelength selection type liquid crystal camera device shown in FIG.
23 is a block diagram showing a full-color wavelength selection optical system used in a second modification of the wavelength selection type liquid crystal camera device shown in FIG.
FIG. 24 is a graph showing a relationship between a liquid crystal refractive index and a transmission characteristic of each liquid crystal filter used in each wavelength selection type liquid crystal camera device according to the present invention.
FIG. 25 is a schematic diagram showing an example of an oil film detection operation of each wavelength-selective liquid crystal camera device according to the present invention.
FIG. 26 is a side view for explaining a detection range when detecting an oil film floating on the sea surface using each wavelength selective liquid crystal camera device according to the present invention.
FIG. 27 is a schematic diagram for explaining a detection range when an oil film floating on the sea surface is detected using each wavelength selection type liquid crystal camera device according to the present invention.
FIG. 28 is a block diagram illustrating an example of a general full-color camera device that has been conventionally known.
FIG. 29 is a cross-sectional view modeling an oil film floating on the sea surface.
30 is a graph showing the relationship between the reflectance and the wavelength when the middle layer shown in FIG. 29 has a thickness of 1 μm and does not absorb light. FIG.
31 is a graph showing the relationship between reflectance and wavelength when the middle layer shown in FIG. 29 has a thickness of 10 μm and does not absorb light. FIG.
32 is a graph showing the relationship between the reflectance and wavelength when the middle layer shown in FIG. 29 has a thickness of 1 μm and absorbs light. FIG.
FIG. 33 is a graph showing the relationship between the reflectance and wavelength when the middle layer shown in FIG. 29 has a thickness of 10 μm and absorbs light.
[Explanation of symbols]
  1: wavelength selection type liquid crystal camera device, 2: wavelength selection optical system, 2a: wavelength selection optical system, 2b: wavelength selection optical system, 3: image processing unit, 4: difference image extraction unit, 5: liquid crystal filter, 6: Lens: 7: Image sensor, 8: Transparent substrate, 9: Transparent electrode film, 10: Dielectric multilayer film, 11: Transparent substrate, 12: Transparent electrode film, 13: Dielectric multilayer film, 14: Liquid crystal layer, 15: Head amplifier circuit, 16: video processing circuit, 17: A / D conversion circuit, 18: frame memory circuit, 19: difference circuit, 20: absolute value circuit, 21: D / A conversion circuit, 22: amplification circuit, 23: Optical bandpass filter, 24: Polarizing film, 30: Wavelength selection type liquid crystal camera device, 31: Wavelength selection optical system, 31a: Wavelength selection optical system, 31b: Wavelength selection optical system, 31c: Wavelength selection optical system, 32: Short wavelength side image processing unit 33: short Long side difference image extraction unit 34: Long wavelength side image processing unit 35: Long wavelength side difference image extraction unit 36: Video composition unit 37: Liquid crystal filter 38: Lens 39: Entrance surface 40: Second Exit surface, 41: reflection / transmission surface, 42: first exit surface, 43: total reflection surface, 44: beam splitter, 45: optical band-pass filter, 46: short wavelength side imaging device, 47: optical band-pass filter , 48: long wavelength side imaging device, 49: head amplifier circuit, 50: video processing circuit, 51: A / D conversion circuit, 52: frame memory circuit, 53: difference circuit, 54: absolute value circuit, 55: D / A conversion circuit, 56: amplification circuit, 57: head amplifier circuit, 58: video processing circuit, 59: A / D conversion circuit, 60: frame memory circuit, 61: difference circuit, 62: absolute value circuit, 63: D / A conversion circuit, 64: increase Circuit: 65: addition circuit, 66: amplification circuit, 67: prism type bandpass filter, 68: front surface, 69: prism, 70: front surface, 71: rear surface, 72: slope, 73: slope, 74: prism, 75: Optical low-pass filter, 76: exit surface, 77: optical high-pass filter, 78: exit surface, 79: optical low-pass filter, 80: entrance surface, 81: prism type low-pass filter, 82: optical low-pass filter, 83: Optical high-pass filter, 84: front surface, 85: prism, 86: front surface, 87: rear surface, 88: slope, 89: slope, 90: prism, 91: optical low-pass filter, 92: entrance surface, 93: exit surface, 94: total reflection surface, 95: emission surface, 96: prism type low-pass filter, 97: optical bandpass filter, 98: optical bandpass filter 99: front surface, 100: prism, 101: front surface, 102: rear surface, 103: slope, 104: slope, 105: prism, 106: optical low-pass filter, 107: entrance surface, 108: exit surface, 109: all Reflective surface, 110: exit surface, 111: wavelength selection type liquid crystal camera device, 112: full color wavelength selection optical system, 112a: full color wavelength selection optical system, 112b: full color wavelength selection optical system, 113: R color image processing unit, 114 : R color difference image extraction unit, 115: G color image processing unit, 116: G color difference image extraction unit, 117: B color image processing unit, 118: B color difference image extraction unit, 119: encoder circuit, 120: liquid crystal filter, 121 : Lens, 123: Dichroic prism, 124: R color image sensor, 125: G color image sensor, 126: B color image sensor, 127: F Deamplifier circuit, 128: Video processing circuit, 129: A / D conversion circuit, 130: Frame memory circuit, 131: Difference circuit, 132: Absolute value circuit, 133: D / A conversion circuit, 134: Amplifier circuit, 135: Head Amplifier circuit 136: Video processing circuit 137: A / D conversion circuit 138: Frame memory circuit 139: Difference circuit 140: Absolute value circuit 141: D / A conversion circuit 142: Amplifier circuit 143: Head Amplifier circuit 144: Video processing circuit 145: A / D conversion circuit 146: Frame memory circuit 147: Difference circuit 148: Absolute value circuit 149: D / A conversion circuit 150: Amplification circuit 151: Optical Band pass filter, 152: polarizing film, 153: sea surface, 154: helicopter, 155: helicopter, 156: optical axis, 157: light beam 158: ray, 159: sea level

Claims (4)

In the wavelength selection type liquid crystal camera device for extracting a specific subject image by converting the optical image obtained by the photographing operation into an optical image for each wavelength range,
A liquid crystal filter having an optical band-pass filter function and whose center wavelength can be changed by voltage;
One image sensor for photoelectrically converting a light image in a wavelength region selected by the liquid crystal filter to generate a video signal;
An image calculation unit that calculates a signal level difference between two images having different wavelengths output from the image sensor and generates a video signal based on an absolute value of the difference;
A wavelength-selective liquid crystal camera device comprising: In the wavelength selection type liquid crystal camera device for extracting a specific subject image by converting the optical image obtained by the photographing operation into an optical image for each wavelength range,
It has an optical bandpass filter function, and its center wavelength can be changed by voltage, and it is included in the optical image of each wavelength region included in the short wavelength side and the long wavelength side from the optical image obtained by the imaging operation. A liquid crystal filter that cyclically extracts a light image in each wavelength range according to the voltage,
A short-wavelength-side image sensor that photoelectrically converts a light image in each wavelength region included in the short-wavelength side selected by the liquid crystal filter to generate a short-wavelength-side video signal;
For each pixel of each short wavelength side video signal output from this short wavelength side image sensor , a signal level difference between the current frame video signal and the previous frame video signal is calculated for each pixel having the same spatial coordinates. , A short wavelength side image calculation unit that generates a short wavelength side video signal based on the absolute value of this difference,
A long-wavelength imaging device that photoelectrically converts a light image in each wavelength region included in the long-wavelength side selected by the liquid crystal filter to generate a long-wavelength video signal;
For each pixel of each long wavelength video signal output from this long wavelength image sensor , the signal level difference between the current frame video signal and the previous frame video signal is calculated for each pixel having the same spatial coordinates. , A long wavelength side image calculation unit that generates a long wavelength side video signal based on the absolute value of this difference,
A video signal synthesizing unit that synthesizes the long wavelength side video signal output from the long wavelength side image calculation unit and the short wavelength side video signal output from the short wavelength side image calculation unit;
A wavelength-selective liquid crystal camera device comprising: In the wavelength selection type liquid crystal camera device for extracting a specific subject image by converting the optical image obtained by the photographing operation into an optical image for each wavelength range,
It has an optical bandpass filter function, and its center wavelength can be changed by voltage, and it is included in the optical image of each wavelength region included in the short wavelength side and the long wavelength side from the optical image obtained by the imaging operation. A liquid crystal filter that cyclically extracts a light image in each wavelength range according to the voltage,
Separating means for separating the light images of the short wavelength side and the long wavelength side selected by the liquid crystal filter into red (R) region, green (G) region, and blue (B) region,
The R light image, the G light image, and the B light image in the short wavelength side and the long wavelength side separated by the separating means are respectively photoelectrically converted, and the short wavelength side and the long wavelength side are respectively photoelectrically converted. A color imaging device for generating an R color video signal, a G color video signal, and a B color video signal in each wavelength range;
Output from the color image sensor , R color video signal in each wavelength region on the short wavelength side, G color video signal, B color video signal and R color video signal in each wavelength region on the long wavelength side, G color video signal, The B color video signal is compared on a pixel-by-pixel basis, and for each of the R, G, and B colors, a signal level difference is calculated for each pixel having the same spatial coordinates. A color image calculation unit for generating an R color video signal, a G color video signal, and a B color video signal;
A color video signal combining unit that combines the R color video signal, the G color video signal, and the B color video signal output from the color image calculation unit to generate a combined color video signal;
A wavelength-selective liquid crystal camera device comprising: The wavelength selective liquid crystal camera device according to any one of claims 1 to 3 ,
The imaging device having the wavelength selecting type liquid crystal camera device, the short wavelength side image pickup device and the long wavelength side imaging element or in front of the color image pickup device, the optical shutter is arranged, by Rukoto operate this optical shutter, intermittent Visualizing,
A wavelength selective liquid crystal camera device characterized by the above.

Images