JPS6362728B2 - - Google Patents
Info
- Publication number
- JPS6362728B2 JPS6362728B2 JP57169879A JP16987982A JPS6362728B2 JP S6362728 B2 JPS6362728 B2 JP S6362728B2 JP 57169879 A JP57169879 A JP 57169879A JP 16987982 A JP16987982 A JP 16987982A JP S6362728 B2 JPS6362728 B2 JP S6362728B2
- Authority
- JP
- Japan
- Prior art keywords
- optical modulator
- operating point
- digital
- low
- voltage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000003287 optical effect Effects 0.000 claims description 20
- 230000000694 effects Effects 0.000 description 4
- 238000012935 Averaging Methods 0.000 description 1
- 229910013641 LiNbO 3 Inorganic materials 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/0121—Operation of devices; Circuit arrangements, not otherwise provided for in this subclass
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/0121—Operation of devices; Circuit arrangements, not otherwise provided for in this subclass
- G02F1/0123—Circuits for the control or stabilisation of the bias voltage, e.g. automatic bias control [ABC] feedback loops
Landscapes
- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Head (AREA)
Description
【発明の詳細な説明】
発明の対称
本発明は光記録デイジタルデイスクの光変調器
に制御に関するものである。DETAILED DESCRIPTION OF THE INVENTION Object of the Invention The present invention relates to controlling an optical modulator of an optical recording digital disk.
発明の目的
デイジタル信号に応じて照射、消光するレーザ
ビームによりピツトを回転円盤上にスパイラル状
に形成して記録する光記録において、レーザビー
ムを変調する光変調器の動作点をデイジタル信号
の平均直流レベルに応じて変化させピツト形状を
デイジタル信号のランレングスに正しく対応させ
る。Purpose of the Invention In optical recording in which pits are formed in a spiral shape on a rotating disk using a laser beam that is irradiated and extinguished in accordance with a digital signal, the operating point of an optical modulator that modulates the laser beam is determined by using the average direct current of the digital signal. The pit shape is changed according to the level to correctly correspond to the run length of the digital signal.
従来技術
図１にレーザビームを用いてデイジタル信号の
ランレングスに対応したピツトを回転円盤に記録
する記録系を示す。レーザ光源１を出たビームは
光変調器２でデイジタル信号を発生する変調信号
源６によりビーム強度がオン、オフされ、ミラー
３で径路を変更したのち対物レンズ４で回転円盤
５上に焦束される。光変調器２には直流バイアス
７が加えられている。回転円盤５の記録面には金
属薄膜又は感光性樹脂が用意され前者の場合には
蒸発、後者の場合には露光によりピツトを形成す
る。光変調器２に加えられるデイジタル変調信号
は記録再生の都合上、直流分を減衰させた、つま
り最大、最小のランレングスを規定した、例えば
第２図に示すような信号が用いられる。同図にお
いて８はクロツク、９はデイジタル変調電圧であ
る。変調電圧９のハイレベル又はローレベルのラ
ンレングスに対応したピツトが記録面に残され
る。レーザビームを高速に変調する為に光変調器
２には電気光学効果又は音響光学効果を用いてい
る。それらの変調特性は正弦波状をしており、例
えばLiNbO3―軸性結晶を用いた変調器ではレー
ザビームの入射強度に対する出射光強度の比Ｒは
変調電圧をVmとすると次式で示される。Prior Art FIG. 1 shows a recording system that uses a laser beam to record pits corresponding to the run length of a digital signal on a rotating disk. The beam intensity of the beam emitted from the laser light source 1 is turned on and off by a modulation signal source 6 that generates a digital signal by an optical modulator 2, and after changing its path by a mirror 3, it is focused onto a rotating disk 5 by an objective lens 4. be done. A DC bias 7 is applied to the optical modulator 2 . A thin metal film or a photosensitive resin is prepared on the recording surface of the rotating disk 5, and pits are formed by evaporation in the former case and exposure to light in the latter case. For convenience of recording and reproducing, the digital modulation signal applied to the optical modulator 2 is a signal whose direct current component is attenuated, that is, a signal whose maximum and minimum run lengths are defined, for example, as shown in FIG. 2, is used. In the figure, 8 is a clock, and 9 is a digital modulation voltage. Pits corresponding to the run length of the high level or low level of the modulation voltage 9 are left on the recording surface. In order to modulate the laser beam at high speed, the optical modulator 2 uses an electro-optic effect or an acousto-optic effect. Their modulation characteristics are sinusoidal; for example, in a modulator using LiNbO 3 -axial crystal, the ratio R of the output light intensity to the laser beam incident intensity is expressed by the following equation, where Vm is the modulation voltage.
Ｒ＝1/2（１＋SinkVm） ｋ：定数
つまり第３図に示すように適度に選ばれた動作
点１２に重畳された変調電圧９に従つて出力光強
度１１は変化し基準レベル１３を越える部分がピ
ツトになる。しかるに変調電圧９が低域直流成分
の変動を有する場合は、それにより第４図に示す
ようにせん移した動作点１４とこれに重畳する変
調電圧９に従い光強度１１は図のように非対称に
変調された出力光となり、ハイ又はローのいずれ
か一方が基準レベルに近づくので、回転円盤５の
記録面に記録されるピツトの形状は悪化してラン
レングスを正しく反映したものとはならない。従
来これを防ぐ為に第５図に示すように光変調器２
に加える変調電圧９を低域波器１６にも加え、
取り出した直流成分を固定バイアス７に重ねて光
変調器２の動作点を決定していた。しかし低域
波器１６の遅延時間により光変調器２に加わる変
調電圧９と低域波器１６の出力との間に時間的
誤差が生じやすいこと、低域波器１６の温度、
湿度による特性の変化等が生じやすい欠点があつ
た。 R = 1/2 (1 + SinkVm) k: constant In other words, as shown in Fig. 3, the output light intensity 11 changes according to the modulation voltage 9 superimposed on the appropriately selected operating point 12, and the portion exceeding the reference level 13 becomes a pit. However, if the modulation voltage 9 has fluctuations in the low-frequency DC component, the light intensity 11 will become asymmetrical as shown in the figure, according to the shifted operating point 14 and the modulation voltage 9 superimposed thereon, as shown in FIG. Since the output light is modulated and either high or low approaches the reference level, the shape of the pits recorded on the recording surface of the rotating disk 5 deteriorates and does not accurately reflect the run length. Conventionally, in order to prevent this, an optical modulator 2 is used as shown in FIG.
The modulation voltage 9 applied to
The operating point of the optical modulator 2 was determined by superimposing the extracted DC component on a fixed bias 7. However, due to the delay time of the low-frequency wave generator 16, a time error tends to occur between the modulation voltage 9 applied to the optical modulator 2 and the output of the low-frequency wave generator 16, and the temperature of the low-frequency wave generator 16,
It had the disadvantage that characteristics tend to change due to humidity.
発明の要点と実施例
本発明の詳細を第６図により説明する。変調電
圧９はｎ段のシフトレジスタ１８を通して光変調
器２に加えられると同時にｎ段のデイジタル相関
器１９に加えられる。デイジタル相関器１９にお
いてクロツク毎に逐次変調電圧９のハイレベル又
はローレベル数のみをクロツク単位で検出する。
例えばハイレベル数のみを検出する場合、デイジ
タルデータのｎクロツク間毎のハイレベルの数ｍ
が１クロツク毎に絶えず出力される。減算器２０
においてその数値ｍからｎ／２を差引く。減算結
果をＤ／Ａ変換器２１に加え変調電圧９の平均直
流成分をアナログ信号の形で取り出し、低域波
器１６′により１クロツク幅の凹凸を平滑し光変
調器２の動作可変電圧１７として使用する。従つ
て低域波器１６′の帯域は第５図の低域波器
１６に比べてはるかに広帯域のものが使えるので
遅延時間もわずかである。Summary of the Invention and Examples The details of the present invention will be explained with reference to FIG. Modulation voltage 9 is applied to optical modulator 2 through n-stage shift register 18 and simultaneously applied to n-stage digital correlator 19 . The digital correlator 19 detects only the number of high or low levels of the successive modulation voltage 9 for each clock.
For example, when detecting only the number of high levels, the number m of high levels every n clocks of digital data is
is constantly output every clock. Subtractor 20
Then subtract n/2 from the value m. The subtraction result is applied to the D/A converter 21, and the average DC component of the modulation voltage 9 is extracted in the form of an analog signal.The low-frequency wave generator 16' smoothes out the unevenness of 1 clock width, and then outputs the operating variable voltage 17 of the optical modulator 2. Use as. Therefore, the band of the low-band filter 16' can be much wider than that of the low-band filter 16 of FIG. 5, so the delay time is also small.
上記動作において変調電圧の直流分を抽出する
単位区間（ｎクロツク区間）の平均化はｎ段のデ
イジタル相関器において行われ、低域波器によ
らないから、その遅延時間はクロツクにより一定
で、その分はシフトレジスタ１８により正しく相
殺される。 In the above operation, the averaging of the unit interval (n clock interval) for extracting the DC component of the modulated voltage is performed in the n-stage digital correlator and does not depend on the low-band filter, so the delay time is constant depending on the clock. That amount is correctly offset by the shift register 18.
低域波器１６′はデイジタル相関器１９に入
つてくる１ビツト単位のデイジタル相関器１９の
出力の変化分を平滑するのみで、シフトレジスタ
１８を通過する変調電圧との遅延時間差はわずか
であり、補償も容易であり、その特性の変化によ
る影響も微小である。シフトレジスタ１８及びデ
イジタル相関器１９の段数は変調電圧９の周波数
成分のうち数KHZ以下の成分が平均化されるよ
うに変調電圧９のビツトクロツク周波数を考慮し
て決めればよい。 The low-pass filter 16' only smoothes the change in the output of the digital correlator 19 in 1-bit units that enters the digital correlator 19, and the delay time difference between it and the modulated voltage passing through the shift register 18 is small. , compensation is easy, and the effects of changes in its characteristics are minimal. The number of stages of the shift register 18 and the digital correlator 19 may be determined in consideration of the bit clock frequency of the modulated voltage 9 so that among the frequency components of the modulated voltage 9, components of several KHz or less are averaged.
本発明の効果
本発明により変調電圧の低域直流成分を検出し
て光変調器の動作点決定電圧に重畳して動作点を
制御することにより、変調電圧のランレングスに
正しく対応したピツトを記録面に記録することが
できる。Effects of the Invention According to the present invention, by detecting the low-frequency DC component of the modulation voltage and controlling the operating point by superimposing it on the operating point determining voltage of the optical modulator, a pit that correctly corresponds to the run length of the modulation voltage is recorded. It can be recorded on the surface.
第１図は記録系を示す図、第２図は変調電圧波
形、第３図は光変調器の変調特性、第４図は動作
点が移動したときの変調特性、第５図は動作点制
御の従来例を示す図、第６図は本発明による動作
点制御の一実施例を示す図。
１…レーザ光線、２…光変調器、３…ミラー、
４…対物レンズ、５…回転円盤、６…変調信号
源、７…バイアス電圧、８…クロツク波形、９…
変調電圧波形、１２，１４…動作点、１１…出力
光強度、１６，１６′…低域波器、１７…可変
バイアス電源、１８…シフトレジスタ、１９…デ
イジタル相関器、２０…減算器、２１…Ｄ／Ａ変
換器。
Figure 1 shows the recording system, Figure 2 shows the modulation voltage waveform, Figure 3 shows the modulation characteristics of the optical modulator, Figure 4 shows the modulation characteristics when the operating point moves, and Figure 5 shows the operating point control. FIG. 6 is a diagram showing an example of operating point control according to the present invention. 1... Laser beam, 2... Optical modulator, 3... Mirror,
4...Objective lens, 5...Rotating disk, 6...Modulation signal source, 7...Bias voltage, 8...Clock waveform, 9...
Modulated voltage waveform, 12, 14... Operating point, 11... Output light intensity, 16, 16'... Low frequency generator, 17... Variable bias power supply, 18... Shift register, 19... Digital correlator, 20... Subtractor, 21 ...D/A converter.
Claims (1)
ーザビームで記録面にピツトを形成する光記録に
おいて、前記デイジタル信号の論理ハイレベル又
は論理ローレベルのランレングスの総和を検出す
る設定値ｎのデイジタル相関器と、検出されたラ
ンレングスの総和からｎ／２ビツトに相当するラ
ンレングス値を差引く減算器と、該減算器出力を
アナログ値に変換するDA変換器と、該DA変換
器により得られたアナログ値を上記光変調器の動
作点電圧に重畳する手段とを有することを特徴と
する光変調器の動作点制御装置。1. In optical recording in which pits are formed on a recording surface with a laser beam modulated with a digital signal by an optical modulator, a digital correlator with a set value n that detects the sum of the run lengths of the logic high level or logic low level of the digital signal. , a subtracter that subtracts a run length value corresponding to n/2 bits from the sum of detected run lengths, a DA converter that converts the output of the subtracter into an analog value, and a DA converter that converts the output of the subtracter into an analog value. An operating point control device for an optical modulator, comprising means for superimposing an analog value on an operating point voltage of the optical modulator.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57169879A JPS5960419A (en) | 1982-09-30 | 1982-09-30 | Operation point controller of optical modulator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57169879A JPS5960419A (en) | 1982-09-30 | 1982-09-30 | Operation point controller of optical modulator |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5960419A JPS5960419A (en) | 1984-04-06 |
| JPS6362728B2 true JPS6362728B2 (en) | 1988-12-05 |
Family
ID=15894645
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP57169879A Granted JPS5960419A (en) | 1982-09-30 | 1982-09-30 | Operation point controller of optical modulator |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5960419A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11533062B1 (en) | 2021-06-29 | 2022-12-20 | Rockwell Collins, Inc. | Non-uniform sampling photonic analog-to-digital converter |
-
1982
- 1982-09-30 JP JP57169879A patent/JPS5960419A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11533062B1 (en) | 2021-06-29 | 2022-12-20 | Rockwell Collins, Inc. | Non-uniform sampling photonic analog-to-digital converter |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5960419A (en) | 1984-04-06 |
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