JP2865064B2 - Light beam emission angle control device and light beam emission position control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light beam emission angle control device and a light beam emission position control device, and more particularly to a light beam emission angle control device used for optical communication between terrestrial communication stations and communication satellites. And a light beam emission position control device.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram showing a configuration example of a conventional light beam position detector described in Japanese Patent Application Laid-Open No. 3-115803. The light beam position detector includes a four-divided photodetector 1, preamplifiers 2 to 5, an addition / subtraction operation circuit 6
, Division circuits 7 and 8, and non-linear circuits 9 and 10. The quadrant photodetector 1 has four optical elements a
~ D. The gain of each of the preamplifiers 2 to 5 is equal. In addition, the part of the code | symbol 11 enclosed with the dashed-dotted line is called a four-quadrant detector.

When a light beam is incident on the four-divided photodetector 1, electric signals corresponding to the light intensities of the incident light beams are output from the respective optical elements a to d. After being amplified by 2 to 5, the electric signals A to
D is input to the addition / subtraction operation circuit 6. Next, the addition / subtraction operation circuit 6 performs an operation ｛(A +) on the electric signals A to D according to the division direction x direction and y direction of the four-division photodetector 1.
D)-(B + C)} and operation {(A + B)-(C +
D)｝ and the sum calculation (A + B + C + D) of the light intensities of the light beams incident on the four-divided photodetector 1 are performed. further,
The division circuits 7 and 8 respectively calculate [{(A + D) − (B + C)} / (A) so that second position detection signals S _2PA and S _{2PB, which} will be described later, do not change depending on the light intensity of the incident light beam.
+ B + C + D)] and the operation [｛(A + B)-(C +
D)｝ / (A + B + C + D)], and these are subjected to a first position detection signal S of the light beam incident on the quadrant photodetector 1.
Output as _1PA , _S1PB .

When the shape of the light beam incident on the four-divided photodetector 1 is circular or elliptical, the dividing circuits 7 and 8 are used.
The characteristic of the output voltage of the light beam with respect to the change of the incident position of the light beam incident on the four-divided photodetector 1, that is, the characteristic of the four-quadrant detector 11, is that the incident position of the light beam is divided into four as shown in FIG. The nonlinearity is such that the further away from the center of the photodetector 1 (the origin in FIG. 8), the smaller the amount of change in the output voltage of the division circuits 7 and 8 with respect to the amount of change in the incident position of the light beam. Therefore, nonlinear circuits 9 and 10 are provided to correct the nonlinear characteristics of the four-quadrant detector 11. The input / output characteristics of the non-linear circuits 9 and 10 are almost linear in a range where the absolute value of the input voltage is small, and in a range where the absolute value of the input voltage is large, a characteristic in which the output voltage rapidly changes with a change in the input voltage, that is, It has nonlinear characteristics that cancel the nonlinear characteristics of the four-quadrant detector 11. The nonlinear circuits 9 and 10 are composed of nonlinear elements such as diodes. Therefore, when the first position detection signals S _1PA and S _1PB are input to the nonlinear circuits 9 and 10, the amount of change in each output voltage and the amount of light incident on the four-split photodetector 1 due to the non-linear characteristics. The relationship with the change amount of the incident position of the beam becomes linear over the entire range, and the output voltages of the nonlinear circuits 9 and 10 are output as the second position detection signals S _2PA and S _2PB .

A light beam emission angle control device using the light beam position detector described above is disclosed in Japanese Patent Application Laid-Open No. Hei.
Japanese Patent Application Laid-Open No. Hei 2-18631 discloses a spatial transmission device for performing optical communication using this type of light beam emission angle control device.

[0006]

By the way, in the above-mentioned conventional light beam position detector, the four-divided light detector 1 is used.
Output optical signals proportional to the light intensities of the light beams incident on the respective optical elements a to d. When a light beam having an asymmetrical intensity distribution enters from the center of the graph, the characteristics of the output voltages of the division circuits 7 and 8 with respect to the change in the incident position of the incident light beam in the four-split photodetector 1 are as shown in FIG. More complex characteristics,
The nonlinear circuits 9 and 10 have a drawback that they cannot be corrected sufficiently. Therefore, when this light beam position detector is used for controlling the position or angle of a transmission light beam in a light beam emission position control device or a light beam emission angle control device of a spatial transmission device, a detection error increases. Also, there is a disadvantage that the position control and the angle control become unstable due to the change of the control loop gain. Also,
In the above-described conventional light beam position detector, non-linear elements such as diodes are used in the non-linear circuits 9 and 10. However, since the non-linear characteristics of these non-linear elements change with temperature, a space transmission device is installed. Also, there is a disadvantage that the detection error of the position or angle of the transmission light beam increases due to the change of the ambient temperature.

The present invention has been made in view of the above circumstances, and provides a light beam emission angle control device and a light beam emission position control device capable of detecting and controlling a light beam emission angle and a light emission position with high accuracy. It is intended to be.

[0008]

According to a first aspect of the present invention, there is provided a light beam emission angle control device for changing an angle of a light transmission unit for emitting a light beam and an angle of the light beam. A driving mechanism section, a lens for forming an image of the light beam whose angle has been changed by the driving mechanism section at a predetermined focal position, and a light receiving surface at the focal position. A four-division photodetector comprising four light receiving elements for dividing and converting each light intensity into an electric signal is provided, an incident position of the light beam is detected from the four electric signals, and a position detection signal is output. A four-quadrant detector; storage means for storing a result obtained by previously measuring characteristics of the position detection signal with respect to the incident position of the light beam or a relational expression obtained from the result; and storage means for storing the storage means in the storage means. Above An output characteristic correction unit that corrects the characteristic of the position detection signal based on the result or the relational expression, and compares an output signal of the output characteristic correction unit with a command value signal indicating an angle to be controlled of the light beam. An operation unit including a comparator that outputs an error signal, and based on the error signal,
And a driver unit for driving the driving mechanism unit.

According to a second aspect of the present invention, there is provided the light beam emission angle control device according to the first aspect, wherein the arithmetic unit comprises:
A loop characteristic compensating unit for compensating for a loop characteristic of a loop including the driving mechanism unit, the lens, the four-quadrant detector, the arithmetic unit, and the driver unit is provided.

Further, in the light beam emission position control device according to the third aspect of the present invention, a light transmission unit that emits a light beam, a positioning unit that changes the position of the light beam, and a position that is changed by the positioning unit And a four-divided photodetector comprising four light-receiving elements for dividing the light beam into four and converting each light intensity into an electric signal. Which detects the incident position of the light and outputs a position detection signal 4
A quadrant detector, storage means for storing a result obtained by previously measuring the characteristic of the position detection signal with respect to the incident position of the light beam, or a relational expression obtained from the result; and a storage means for storing the relational expression. An output characteristic correction unit that corrects the characteristic of the position detection signal based on the result or the relational expression, and compares an output signal of the output characteristic correction unit with a command value signal indicating a position to control the light beam. Further, it is characterized by comprising an arithmetic unit having a comparator for outputting an error signal, and a driver unit for driving the positioning unit based on the error signal.

The invention according to claim 4 relates to the light beam emission position control device according to claim 3, wherein the arithmetic unit comprises:
A loop characteristic compensating unit for compensating for a loop characteristic of a loop including the positioning unit, the four-quadrant detector, the arithmetic unit, and the driver unit is provided.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. The description will be specifically made using an embodiment. First Embodiment FIG. 1 is a block diagram showing an electrical configuration of a light beam emission angle control device according to a first embodiment of the present invention. The light beam emission angle control device of this example includes a four-quadrant detector 11,
A light transmission unit 12, a drive mechanism unit 13, an optical system 14, a lens 15, a light beam emission angle command unit 16,
7 and a driver section 18. The four-quadrant detector 11 has the same configuration as the four-quadrant detector 11 shown in FIG.
The first position detection signals S _1PA and S _1PB are output. Optical transmitter 1
Reference numeral 2 denotes a light emitting element such as a semiconductor laser, a driver for driving the light emitting element, and an optical system for converting a light beam emitted from the light emitting element into parallel light. The drive mechanism 13 is configured by a mirror that can change the angle of the light beam emitted from the light transmitter 12. Optical system 14
Is composed of an element (for example, a beam splitter) for splitting a light beam, but a reflective element or an element for changing the magnification of the light beam may be added as the case may be. The lens 15 is formed of a condensing lens, and converts a change in the output angle of the output light beam 19 into a change in the position on the quadrant photodetector 1.

The light beam emission angle command section 16 is composed of software or hardware having a function for generating a desired command value, and outputs a light beam emission angle command value signal. The calculation unit 17 calculates the first position detection signal S
_A driver control signal is supplied to the driver unit 18 in order to drive the drive mechanism unit 13 so that _1PA and S _{1PB coincide} with the light beam emission angle command value signal. Here, FIG. 2 shows an example of the configuration of the calculation unit 17. The operation unit 17 includes an output characteristic correction unit 20, a comparator 21, a loop characteristic compensation unit 22,
And a conversion unit 23.

The output characteristic correction unit 20 corrects the non-linear output characteristics of the four-quadrant detector 11, that is, the characteristics of the first position detection signals S _1PA and S _1PB so as to be linear.
It is output as a light beam angle fluctuation signal of the outgoing light beam 19 shown in FIG. The comparator 21 compares the light beam angle variation signal supplied from the output characteristic correction unit 20 with the light beam emission angle command value signal supplied from the light beam emission angle command unit 16 and outputs an error signal. . The loop characteristic compensating unit 22 includes a four-quadrant detector 11, a computing unit 17, a driver unit 18, a driving mechanism unit 13, an optical system 14, and a lens 1.
5 to compensate the frequency of the error signal supplied from the comparator 21 in order to compensate for the loop control characteristic of the loop constituted by 5. The converter 23 converts the error signal frequency-compensated by the loop characteristic compensator 22 into a driver control signal for controlling the driver 18. Driver part 1
Reference numeral 8 denotes a drive circuit that drives the drive mechanism 13 based on a driver drive signal supplied from the calculation unit 17.

Next, FIG. 3 shows the concept of the configuration of the output characteristic correction section 20. The output characteristic correction unit 20 can _write , for example, a RAM or a rewritable relational expression representing the non-linear characteristic of the first position detection signals S _1PA and S _1PB with respect to the incident position of the light beam incident on the _quadrant photodetector 1. It is stored in a form stored in a ROM or the like. This relational expression is represented by a polynomial approximation expression, an exponential function, or an expression that varies depending on the output range of the four-quadrant detector 11. Then, the first signal supplied from the four-quadrant detector 11
The position detection signals S _1PA and S _1PB are substituted into this relational expression, and the obtained result is used as a light beam angle fluctuation signal as a comparator 21.
To supply. Further, instead of the relational expression, a table representing the above-described nonlinear characteristic is stored in a RAM, a rewritable ROM, or the like, and when the first position detection signals S _1PA and S _1PB are supplied, the table is referred to. Alternatively, the light beam angle fluctuation signal may be obtained.

In order to perform optical communication using the spatial transmission device having the light beam emission angle control device having the above configuration, first, the spatial transmission device is installed at a desired communication station or communication satellite.
Find the relational expression. For this, at a predetermined distance on the optical axis of the outgoing light beam 19 from the optical system 14 shown in FIG.
An optical angle detector that can measure the center of gravity is installed. That is, the position at which the light beam emitted from the optical communication unit 12 is incident on the four-quadrant detector 11 is changed by driving the drive mechanism unit 13, and the amount of change in the incident position is changed by the optical angle detector. While measuring as the angle change of 19, 4
The amount of change in the first position detection signals S _1PA and S _1PB output from the quadrant detector 11 is measured. Then, the obtained measurement results are shown in a graph as shown in FIG. 4, and a relational expression is obtained from this graph. The relational expression is, for example, the output characteristic correction unit 2
0 is stored in an internal RAM or a rewritable ROM. FIG.
Is a case where the shape of the light beam incident on the four-split photodetector 1 of the four-quadrant detector 11 is a circular Gaussian beam, and the incident position of the light beam is at the center of the four-split photodetector 1 (see FIG. 4 (the origin of No. 4), the non-linear characteristic that the amount of change in the first position detection signals S _1PA and S _1PB with respect to the amount of change in the incident position of the light beam becomes smaller.

After the relational expression has been obtained by the above procedure and the initial setting has been made, transmission to another communication station is performed by the optical transmission unit 1.
In 2, for example, a light beam whose light intensity is modulated by information to be transmitted is emitted. Thereby, the optical transmission unit 1
The light beam emitted from 2 is incident on the optical system 14 after being controlled to a desired emission angle by the drive mechanism 13,
The light beam of most of the light intensity is reflected, emitted from the spatial transmission device as an emitted light beam 19, and transmitted to the destination. On the other hand, a part of the light beam transmitted through the optical system 14 is condensed by the lens 15 and
An image is formed on the split photodetector 1 (see FIG. 7). As a result, the change in the output angle of the output light beam 19 is converted into a change in the position on the four-split photodetector 1, and the change in the position is detected by the four-quadrant detector 11, and the first position detection signal S
_1PA and _S1PB are output and input to the operation unit 17.

In the output characteristic correction unit 20 of the calculation unit 17, the first position detection signals S _1PA and S _1PB are substituted into the relational expressions stored in the internal RAM or the rewritable ROM, and the obtained result is obtained. It is output as a light beam angle variation signal. This light beam angle variation signal is compared with the light beam emission angle command value signal supplied from the light beam emission angle command unit 16 in the comparator 21, and an error signal is output from the comparator 21. This error signal is frequency-compensated by the loop characteristic compensator 22 and then converted to a driver control signal by the converter 23. The driving mechanism 13 is driven in the driver 18 based on the driver driving signal.

As described above, according to the configuration of this example, the first position detection signals S _1PA ,
The non-linear characteristic of S _1PB with respect to the incident position of the light beam incident on the four-split photodetector 1 is measured and faithfully expressed by a relational expression, which is corrected by the calculation unit 17 using this relational expression. Even if the shape is a circle or an ellipse or the light intensity distribution of the light beam is non-uniform, for example, the intensity distribution is asymmetrical from the center of the light beam, the nonlinear characteristic is complicated. Control can be performed with high accuracy. Further, since a nonlinear element having a temperature characteristic is not used for correcting the nonlinear characteristic as in the related art, there is no influence of a change in the ambient temperature. Furthermore, since the loop control characteristic is compensated for by the loop characteristic compensating unit 22 by frequency-compensating the error signal supplied from the comparator 21, even if the light intensity distribution of the light beam is not uniform, the control loop gain is This does not change, and thus, the angle control of the outgoing light beam 19 can be performed with high accuracy.

Second Embodiment Next, a second embodiment will be described. FIG. 5 is a block diagram showing an electrical configuration of a light beam emission position control device according to a second embodiment of the present invention. In this figure, parts corresponding to the respective parts in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. In the light beam emission position control device shown in this figure, instead of the drive mechanism unit 13, the light beam emission angle command unit 16, the calculation unit 17, and the driver unit 18 shown in FIG.
Positioning section 31, light beam emission position command section 32,
An arithmetic unit 33 and a driver unit 34 are newly provided. In FIG. 5, the lens 15 shown in FIG. 1 is removed.

The positioning section 31 includes a two-axis stage mount and the like, and changes the position of the light beam emitted from the light transmitting section 12. The light beam emission position command unit 32 is configured by software or hardware having a function for generating a desired command value, and outputs a light beam emission position command value signal. Further, the arithmetic unit 33 supplies a driver control signal to the driver unit 34 to drive the positioning unit 31 so that the first position detection signals S _1PA and S _{1PB coincide} with the light beam emission position command value signal. . Here, FIG. 6 shows an example of the configuration of the arithmetic unit 33. The calculation unit 33 includes an output characteristic correction unit 35, a comparator 36, a loop characteristic compensation unit 37, and a conversion unit 38. The output characteristic correction unit 35 corrects the characteristics of the first position detection signals S _1PA and S _1PB supplied from the four-quadrant detector 11 to be linear, and _outputs the light beam of the outgoing light beam 19 shown in FIG. Output as a position change signal. The comparator 36 compares the light beam position fluctuation signal supplied from the output characteristic correction unit 35 with the light beam emission position command value signal supplied from the light beam emission position command unit 32, and outputs an error signal. . The loop characteristic compensator 37 includes a four-quadrant detector 11, a calculator 33, a driver 34, and a positioning unit 31.
The error signal supplied from the comparator 36 is frequency-compensated in order to compensate for the loop control characteristic of the loop formed by the optical system 14 and the optical system 14. The converter 38 converts the error signal frequency-compensated by the loop characteristic compensator 37 into a driver control signal for controlling the driver 34.
The driver unit 34 includes a drive circuit that drives the positioning unit 31 based on a driver drive signal supplied from the calculation unit 33.

In order to perform optical communication using the spatial transmission device having the light beam emission position control device having the above configuration, first, the spatial transmission device is installed at a desired communication station or communication satellite.
Find the relational expression. For this, a predetermined distance on the optical axis of the outgoing light beam 19 from the optical system 14 shown in FIG.
An optical position detector or the like that can measure the center of gravity is installed. That is, the position at which the light beam emitted from the optical communication unit 12 is incident on the four-quadrant detector 11 is changed by driving the positioning unit 31, and the incident position change amount is changed by the optical position detector. The amount of change in the first position detection signals S _1PA and S _1PB output from the four-quadrant detector 11 is measured while measuring the amount of change in position. Then, the obtained measurement results are represented in a graph, and a relational expression is obtained from the graph.
The relational expression is stored in, for example, a RAM or a rewritable ROM inside the output characteristic correction unit 35.

After the relational expression has been obtained by the above procedure and the initial setting has been made, transmission to another communication station is performed by the optical transmission unit 1.
In 2, for example, a light beam whose light intensity is modulated by information to be transmitted is emitted. Thereby, the optical transmission unit 1
The light beam emitted from the light source 2 is controlled to a desired emission position by the positioning unit 31 and then is incident on the optical system 14, and the light beam with the most light intensity is reflected and spatially transmitted as the emitted light beam 19. It is emitted from the device and transmitted to the destination. On the other hand, a part of the light beam transmitted through the optical system 14 is incident on the quadrant photodetector 1 (see FIG. 7) of the four-quadrant detector 11. Thus, the four-quadrant detector 11 detects a change in the position of the emitted light beam 19,
The position detection signals S _1PA and S _1PB are output and input to the calculation unit 33.

In the output characteristic correction unit 35 of the calculation unit 33, the first position detection signals S _1PA and S _1PB are substituted into the relational expressions stored in the internal RAM or the rewritable ROM, and the obtained result is obtained. It is output as a light beam position fluctuation signal. This light beam position variation signal is compared with the light beam emission position command value signal supplied from the light beam emission position command unit 32 in the comparator 36, and an error signal is output from the comparator 36. This error signal is frequency-compensated in the loop characteristic compensator 37 and then converted into a driver control signal in the converter 38. On the basis of the driver drive signal, the driver section 34 causes the positioning section 3
1 is driven.

As described above, according to the configuration of this example, the first position detection signals S _1PA ,
The non-linear characteristic of S _1PB with respect to the incident position of the light beam incident on the four-split photodetector 1 is measured and faithfully expressed by a relational expression. Even if the shape is a circle or an ellipse, or the light intensity distribution of the light beam is non-uniform and the nonlinear characteristics are complicated, the position of the emitted light beam 19 can be controlled with high accuracy. Further, since a nonlinear element having a temperature characteristic is not used for correcting the nonlinear characteristic as in the related art, there is no influence of a change in the ambient temperature. Further, since the loop control characteristic is compensated in the loop characteristic compensator 37 by frequency-compensating the error signal supplied from the comparator 36, the control loop gain is maintained even if the light intensity distribution of the light beam is not uniform. The position of the output light beam 19 can be controlled with a high degree of accuracy.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the design of the present invention does not depart from the gist of the present invention. Modifications are included in the present invention. For example, in the above-described embodiment, the relational expression shows an example in which the spatial transmission device is obtained only once immediately after being installed in a desired communication station or communication satellite, but the shape of the light beam emitted from the light emitting element and Since the light intensity distribution varies depending on the individual light emitting element and changes with the passage of time, the light intensity distribution may be obtained every time the light emitting element is replaced or every time a predetermined time elapses.

[0027]

As described above, according to the light beam emission angle control device and the light beam emission position control device of the present invention, the non-linear characteristic of the position detection signal with respect to the incident light beam position is measured and faithfully related. It is expressed by an equation, and correction is performed using this relational expression.Thus, even if the shape of the light beam is a circle or an ellipse, or the light intensity of the light beam is non-uniform and the nonlinear characteristic is complicated, it can be sufficiently corrected. In addition, angle control and position control of the emitted light beam can be performed with high accuracy. Further, since a nonlinear element having a temperature characteristic is not used for correcting the nonlinear characteristic as in the related art, there is no influence of a change in the ambient temperature. Further, in another configuration of the present invention,
In the loop characteristic compensating means, the error signal supplied from the comparator is frequency-compensated to compensate for the loop control characteristic. Therefore, even if the light intensity distribution of the light beam is not uniform, the control loop gain does not change. This also makes it possible to control the angle and position of the emitted light beam with high accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of a light beam emission angle control device according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating an example of a configuration of a calculation unit according to the embodiment.

FIG. 3 is a conceptual diagram illustrating an example of a configuration of an output characteristic correction unit according to the embodiment.

FIG. 4 is a diagram illustrating an example of a non-linear characteristic of an output voltage of a four-quadrant detector with respect to an incident light beam position in the embodiment.

FIG. 5 is a block diagram showing an electrical configuration of a light beam emission position control device according to a second embodiment of the present invention.

FIG. 6 is a block diagram illustrating an example of a configuration of an output characteristic correction unit according to the embodiment.

FIG. 7 is a block diagram illustrating a configuration example of a conventional light beam position detector.

FIG. 8 is a diagram illustrating an example of a nonlinear characteristic of an output voltage of a conventional four-quadrant detector with respect to an incident light beam position.

[Explanation of symbols]

 Reference Signs List 1 quadrant photodetector 11 4 quadrant detector 12 optical transmission unit 13 drive mechanism unit 14 optical system 15 lens 16 light beam emission angle command unit 17, 33 calculation unit 18, 34 driver unit 19 emission light beam 20, 35 output characteristics Correction unit 21, 36 Comparator 22, 37 Loop characteristic compensation unit 23, 38 Conversion unit 31 Positioning unit

Claims (4)

(57) [Claims] An optical transmission unit that emits a light beam; a driving mechanism that changes an angle of the light beam; and a lens that forms an image of the light beam whose angle has been changed by the driving mechanism at a predetermined focal position. A light-receiving surface is provided at the focal position, and a four-segment photodetector including four light-receiving elements that divides the imaged light beam into four and converts each light intensity into an electric signal,
A four-quadrant detector that detects an incident position of the light beam from the four electric signals and outputs a position detection signal; and a result obtained by previously measuring characteristics of the position detection signal with respect to the incident position of the light beam. Or storage means for storing a relational expression obtained from the result, an output characteristic correction unit for correcting the characteristic of the position detection signal based on the result or the relational expression stored in the storage means, and the output characteristic An arithmetic unit including a comparator that compares an output signal of a correction unit and a command value signal representing an angle to be controlled of the light beam and outputs an error signal; andthe driving mechanism unit based on the error signal. A light beam emission angle control device, comprising: a driver unit for driving. 2. The operation unit includes a loop characteristic compensation unit that compensates for a loop characteristic of a loop including the driving mechanism unit, the lens, the four-quadrant detector, the operation unit, and the driver unit. The light beam emission angle control device according to claim 1, further comprising: 3. A light transmitting unit for emitting a light beam, a positioning unit for changing the position of the light beam, and a light beam whose position has been changed by the positioning unit is incident, and the light beam is divided into four parts. A four-quadrant photodetector comprising four light receiving elements for converting each light intensity into an electric signal; a four-quadrant detection for detecting an incident position of the light beam from the four electric signals and outputting a position detection signal; And a storage unit for storing a result obtained by previously measuring characteristics of the position detection signal with respect to the incident position of the light beam or a relational expression obtained from the result, and the result stored in the storage unit. Or an output characteristic correction unit for correcting the characteristic of the position detection signal based on the relational expression, and an output signal of the output characteristic correction unit and a command value signal indicating a position to be controlled of the light beam. And a driver for driving the positioning unit based on the error signal. . 4. The operation unit includes a loop characteristic compensation unit that compensates for a loop characteristic of a loop including the positioning unit, the four-quadrant detector, the operation unit, and the driver unit. The light beam emission position control device according to claim 3.