JPH07318817A - Optical chopping device - Google Patents

Abstract

PURPOSE:To realize an optical chopping device which converts continuous incident light to intermittent light rays and is capable of doubling the number of chopping times per on revolution as compared with heretofore. CONSTITUTION:This optical shopping device has a rotary drum 10 which is formed with odd number sets of paired patterns of transmissive parts 20 and shielded parts 30 along a cylindrical surface and a drum cover 40 which arranged concentrically therewith so as to cover this rotary drum and has incident windows 50 an exit windows 60 in the positions facing the transmissive parts 20 and the shielding parts 30. The rotary drum 10 is rotated by a motor to intermit the light emitted from the exit windows 6. The exact chopping control is executed by providing the device with respective control sections, feedback sections, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical chopping device for converting continuous rays such as ultraviolet rays, visible rays and infrared rays into intermittent rays.

[0002]

2. Description of the Related Art There are continuous rays of various wavelengths such as ultraviolet rays, visible rays and infrared rays. These light rays are used as continuous light, and there are many applications in which the continuous light is made into intermittent light and the devices are operated by using the intermittent light. For example, intermittent light is used as strobe light of an image pickup device. Alternatively, it is used as a reference beam for an optical measuring device. There are various types of optical chopping devices for converting continuous light into intermittent light, for example, a transmitting part and a shielding part are provided on a rotating disk along the circumferential direction, and the rotating disk is rotated to emit light only from the transmitting part. There is one that passes the light and outputs intermittent light. In this case, the number of choppings depends on the number of patterns of pairs of the transmissive part and the shield part.

[0003]

In the case of the above-described conventional optical chopping device, since the number of pairs of the transmitting portion and the shielding portion per rotation of the rotating disk corresponds to the number of pairs of patterns, the number of pairs of chopping patterns should be increased. There is no choice but to increase the number of. There is also a method of increasing the rotation speed of the rotating disk, but this is also limited.

The present invention was devised in view of the above circumstances, and an optical device capable of realizing a high chopping frequency by making the number of choppings per rotation at least twice that of the conventional one by a relatively small and simple means. An object is to provide a chopping device.

[0005]

In order to achieve the above object, the present invention has an odd number of patterns having a cylindrical surface and having a pair of a transmission part and a shielding part along the rotation direction of the cylindrical surface. Rotating drums arranged individually, and concentric circular cylinders that cover the rotating drums, are arranged apart from each other along an optical axis orthogonal to the rotation axis of the rotating drums, and are located at a position facing the pattern with an entrance window and It is composed of a drum cover that forms an emission window and a motor that rotates the rotary drum around the rotation axis, and intermittent light is intermittently generated by the pattern that rotationally moves continuous light that has entered along the optical axis from the entrance window. The light chopping device is configured to be converted into the light and emitted from the emission window. Further, the rotating drum is formed of a material that is opaque to the wavelength of the continuous light, and is provided with a monitor unit that monitors the number of times the intermittent light is intermittent and outputs a monitor signal. The monitor means is a non-contact type. Furthermore,
Characterized in that it comprises a counting means for counting the monitor signal and outputting the count signal, characterized by comprising a comparison and determination means for comparing and determining the count signal by the counting means and the set value, and outputting a correction signal, It is characterized in that it is provided with feedback means for feeding back the correction signal of the comparison and determination means to the motor side, and is provided with the monitor means and an external output means for outputting the count signal of the counting means to the outside. is there.

[0006]

According to the present invention, the pattern of the odd-numbered transmission and shield pairs formed on the rotary drum is intermittently aligned with the entrance window and the exit window of the drum cover, so that one
The number of choppings per rotation is increased, and it is possible to obtain intermittent light having a frequency at least twice that of the conventional one. That is,
In the optical path from the entrance window to the exit window, the pattern of the pair of transmissive part and shield part crosses twice with different phases, so the number of choppings is doubled.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a conceptual configuration of an optical chopping device according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the XY plane of FIG. 1 when a pair of patterns of a transmission part and a shielding part are provided. 3 is a plan view for explaining the chopping action in FIG. 2, FIG. 4 is a diagram showing the chopping action in FIG. 3 with time, and FIG. 5 corresponds to claim 1 or 2 of the present invention. 6 is a block diagram of an embodiment, FIG. 6 is a block diagram of another embodiment of the present invention, and FIG. 7 is a further block diagram.

In FIG. 1, an optical chopping device 1 comprises a cylindrical rotary drum 10 which rotates around a vertical rotary axis (hereinafter referred to as Z axis), and a drum cover 40 which is a concentric cylindrical body and covers the rotary drum 10. The rotating drum 10 is formed with an odd number of transmissive portions 20 and shield portions 30 as a pair of patterns along the cylindrical surface. It should be noted that the orthogonal axes in the horizontal plane orthogonal to the Z axis and intersecting at the origin C are defined as the X axis and the Y axis. on the other hand,
An entrance window 50 and an exit window 60 are formed on the circumferential surface of the fixed drum cover 40 so as to face the transmissive portion 20 and the shield portion 30. The entrance window 50 and the exit window 60 are arranged so as to face each other along the X axis, and the optical axis (X axis) connecting the two passes through the origin C.
The light rays to be chopped travel along the X axis and enter through the entrance window 50 and exit through the exit window 60. By rotating the rotary drum 10 around the Z axis, the transmissive portions 20 and the shield portions 30 of a large number of pairs of patterns sequentially pass through the entrance window 50 and the exit window 60, the windows are opened and closed, and the light rays are chopped. To be done.

Although FIG. 1 shows five sets of the transmitting part 20 and the shielding part 30, for convenience of explanation, an optical chopping device having three pairs of patterns shown in FIG. 2 will be described.
Fig. 2 shows X, which is obtained by cutting Fig. 1 at the position of the origin C at right angles to the Z axis.
It is a Y top view. On the rotary drum 11, transparent portions 21, 22, 23 having a central angle of 90 ° and shielding portions 31, 32, 33 having a central angle of 30 ° are alternately formed as a pair of patterns. On the other hand, the drum cover 41 is formed with an entrance window 51 having a central angle of 30 ° and an exit window 61 having a central angle of 30 °.

First, FIG. 2 shows the initial position of the rotary drum 11 (the position shown in FIG. 3). That is, the position where the clockwise side end portion of the shield portion 31 is aligned with the counterclockwise side end portion of the emission window 61 is the position. In this case, the counterclockwise side end portion of the shielding portion 33 is located at the position corresponding to the clockwise side end portion of the entrance window 51 of the drum cover 41 from the above-described distribution of the central angles, and the shielding portion 32 is located at the entrance window 51 and the exit window. It is arranged at an intermediate position of 61.

FIG. 3 further shows the rotary drum 1 from the above position.
1 shows a state in which 1 is rotated by an angle of 15 °. The position is a position advanced by 15 ° in the clockwise direction from the position, and the position or position represents a position further advanced by 15 ° respectively. The incident light ray L1 enters through the incident window 51, and the outgoing light ray L2 exits through the outgoing window 61. FIG. 4 shows from position to position and opening / closing of the entrance window 51 (O
N, OFF), the ON / OFF state of the emission window 61, and the ON / OFF state of the emission light beam L2 emitted from the emission window 61.
The graph shows the OFF state, that is, the state of the chopping frequency over time. In the figure, the ON level shows the most open state, and the OFF level shows the closed state. The number of choppings is ON for the outgoing light ray L2
Determined by the number of states.

Next, the chopping operation of this embodiment will be described with reference to FIGS. As described above, the shielding parts 31, 3
2, 33 are in the positions, and the entrance window 51 and the exit window 61
The incident light ray L1 in (3) passes through the origin C without being shielded by any of the shielding portions 31, 32, 33, and the emission light ray L2 is emitted from the emission window 61. This state is shown in FIG.
Denote by N. After that, when the outgoing light ray L2 is blocked, it is OF
Indicated by F. Next, when the shielding portions 31, 32, 33 and the transmitting portions 21, 22, 23 are integrally rotated by 15 degrees in the clockwise direction, the incident light ray L1 is transmitted from the incident window 51 to the shielding portions 31, 32, 33. Origin C
However, a half angle of the opening angle of the emission window 61 is shielded from the emission window 61 by the shielding portion 31. Therefore, the outgoing light ray L2 in this case is in the transition stage from transmission to light shielding,
In FIG. 4, the graph is a downward-sloping graph at an intermediate position between ON and OFF. Further, when the shielding portions 31, 32, 33 and the transmitting portions 21, 22, 23 are integrally rotated by 15 degrees in the clockwise direction, the incident light beam L1 is transmitted from the incident window 51 to the shielding portions 31, 32, 33. Even though it passes through the origin C without being shielded from light, it is completely shielded by the shielding portion 31. Therefore, in this case, the outgoing ray L2 is shielded and turned off in FIG. The above rotations are sequentially performed, and the number of times of chopping of the emitted light beam L2 when the light shielding unit 31 is rotated once from the position as the starting point is 6 times as shown in FIG. Twice as many times are chopped as compared to three times.

The rotating drums 10 and 11 and the drum cover 4
0 and 41 are made of a material that is opaque to the wavelength of the continuous light that is incident so that the incident light does not pass through the portions other than the entrance windows 50 and 51 and the exit windows 60 and 61 to cause an incorrect chopping state. It needs to be formed. For example, metal, resin, quartz or the like can be used. In particular, metals are preferable because they are opaque in the wavelength range from ultraviolet rays to infrared rays.

FIG. 5 shows that the motor 80 for rotating the rotary drum 10 is attached to the optical chopping device shown in FIG.
This is an embodiment in which a motor control unit 100, a system control unit 110, and the like for controlling it are provided. In FIG. 5, a rotary shaft mounting plate 70 is fixed to the bottom surface of the rotary drum 10 and is connected to a drive shaft 80a of a motor 80 having a Z axis as a rotary shaft. The motor 80 is fixed to a motor pedestal 90 having the same diameter as the drum cover 40, and the drum cover 40 is connected to the motor pedestal 90. The drum cover 40 includes a drum cover 1 for preventing stray light from entering the drum cover 40.
60 is engaged. The motor 80 is a motor control unit 100.
Controlled by. Commands for operating conditions such as driving, stopping, and chopping frequency of the motor 80 by the motor control unit 100 are given through the system control unit 110, and are given by an operator's input operation on the keyboard 130. The input command is displayed on the display unit 170 via the system control unit 110. In the present embodiment, the motor 8
Examples of 0 include a servo motor, a stepping motor, a superconducting motor, an ultrasonic motor, and an induction motor. In particular, it is desirable that the servo motor is small and has good controllability.

FIG. 6 further includes a sensor 120 as monitoring means, a counting section 140 as counting means,
An embodiment will be shown in which the comparison / determination unit 150 and the feedback means are provided as the comparison / determination means. The sensor 120 constituting the monitoring means is attached to face the rotary drum 10 and monitors whether or not the rotation of the motor 80 is stable at a constant speed. The sensor 120 may be either a contact type or a non-contact type, but a non-contact type such as a photodiode, a transmission type photoelectric switch, a reflection type photoelectric switch, a magnetic proximity switch or the like is preferable in that it does not apply a load to the rotating drum 10 side. The counting unit 140 counts the monitor signal output from the sensor 120 and outputs the count signal, and the comparison and determination unit 150 compares and determines the count signal and the set value, and outputs the correction signal that is the determination result. is there. Further, the feedback means controls the rotation of the motor 80 based on the correction signal. In the present embodiment, the number of times of ON or OFF corresponding to the transmission part 20 and the shielding part 30 obtained by the sensor 120 is counted to monitor the rotation speed, and is also fed back to the motor control part 100 to change the rotation speed. Is to correct. In this embodiment, constituent elements similar to those in the previous embodiment are designated by the same reference numerals. In FIG. 6, the system control unit 110 is set with initial conditions from the keyboard 130. Here, the initial conditions are driving,
Stop, chopping frequency. When the setting signal S1 is given as described above and the system control unit 110 gives the rotation signal S5 to the motor control unit 100, the system control unit 110 is controlled to rotate at a constant speed as follows. First, the motor control unit 100
The rotation signal S5 is given to the motor 80 and the motor 80 rotates. When the motor 80 rotates, the sensor 120 provides the ON / OFF periodic monitor signal S2 to the counting unit 140. The counting section 140 generates a count signal S3 and inputs it to the comparison and determination section 150. The comparison / determination unit 150 compares S3 with the set numerical value S6 corresponding to the chopping frequency given by the system control unit 110, and gives the difference to the system control unit 110 as a correction signal S4. The system control unit 110 gives the corrected rotation signal S5 to the motor control unit 100 according to the correction signal S4. By repeating the above operation, fluctuations in the rotation speed of the motor 80 are corrected, and control is performed so that the chopping frequency is given by the initial condition. The initial condition and the chopping frequency during operation are displayed on the display unit 170.

FIG. 7 shows still another embodiment of the present invention. It is an embodiment in which an external signal output function of a reference chopping frequency necessary when using the embodiment of FIG. 6 in a lock-in measurement method or the like is further added. System control unit 1
10, the reference chopping frequency signal S to the outside
7 is output.

[0017]

According to the present invention, the following remarkable effects are obtained. 1) Providing an odd number of pairs of patterns of a transmission part and a shielding part on a rotary drum, and incorporating the pattern into a drum cover having an entrance window and an exit window to rotate it, it is possible to provide a chopping frequency double that of the conventional one. A high chopping frequency is realized. 2) By providing a motor control unit, a system control unit, a counter unit, a comparison / determination unit and a feedback unit, an external signal output unit, and the like, a desired chopping frequency can be accurately obtained, and this can be used as an external output. I can. 3) By adopting the rotating drum and the drum cover arranged concentrically, the device structure is compact and compact.

[Brief description of drawings]

FIG. 1 is a perspective view showing a conceptual configuration of an embodiment of the present invention.

2 is a cross-sectional view taken along the X and Y planes of FIG. 1 in which a pair of patterns of a transparent portion and a shield portion is provided.

3 is an explanatory plan view for explaining the chopping action of FIG.

FIG. 4 is a diagram showing the chopping action of FIG. 3 over time.

FIG. 5 is a configuration diagram of an embodiment of the present invention having a motor control unit.

FIG. 6 is a configuration diagram of an embodiment of the present invention including a monitor means, a count means, a comparison / determination means, a feedback means, and the like.

FIG. 7 is a configuration diagram of an embodiment in which a signal external output function is added.

[Explanation of symbols]

 10 rotating drum 11 rotating drum 20 transmission part 21 transmission part 22 transmission part 23 transmission part 30 shield part 31 shield part 32 shield part 33 shield part 40 drum cover 41 drum cover 50 entrance window 51 entrance window 60 exit window 61 exit window 70 rotary shaft attachment Plate 80 Motor 80a Drive shaft 90 Motor pedestal 100 Motor control unit 110 System control unit 120 Sensor 130 Keyboard 140 Counting unit 150 Comparison determining unit 160 Drum cover 170 Display unit

Claims (8)

[Claims] 1. A rotary drum having a cylindrical surface and arranging an odd number of patterns each including a pair of a transmitting portion and a shielding portion along a rotation direction of the cylindrical surface, and a concentric cylindrical body covering the rotating drum. The drum cover that forms an entrance window and an exit window at positions facing each other and is spaced apart from each other along an optical axis orthogonal to the rotation axis of the rotary drum, and the rotary drum around the rotation axis. An optical chopping device comprising a rotating motor, characterized in that continuous light that has entered along the optical axis from the entrance window is intermittently converted into intermittent light by the pattern that rotates and is emitted from the exit window. . 2. The optical chopping device according to claim 1, wherein the rotary drum is formed of a material that is opaque to the wavelength of the continuous light. 3. The optical chopping device according to claim 1, further comprising monitor means for monitoring the number of times of intermittent light and outputting a monitor signal. 4. The optical chopping device according to claim 3, wherein said monitor means is a non-contact type. 5. The optical chopping device according to claim 3, further comprising counting means for counting the monitor signal and outputting the count signal. 6. The optical chopping device according to claim 5, further comprising a comparison / judgment device for comparing and judging the count signal from the count device with a set value and outputting a correction signal. 7. The optical chopping device according to claim 6, further comprising foot-back means for foot-backing the correction signal of the comparison / determination means to the motor side. 8. The optical chopping device according to claim 5, further comprising external output means for outputting the count signal of the counting means to the outside.