JP5278746B2 - Optical damage avoidance device for laser equipment - Google Patents

Description

  The present invention relates to an optical damage avoidance device for a laser device that generates high-power laser light. More specifically, the present invention relates to an optical damage avoidance device for a laser device having an oscillation unit and an amplification unit that amplifies laser light generated from the oscillation unit.

  Optical components such as mirrors, lenses, optical fibers, and optical crystals used in laser devices may suffer optical damage when the laser light becomes high power. Normally, when the oscillation is normal, the optical damage is not caused. However, when the oscillation becomes unstable due to various causes, the peak power of the laser beam is increased and the optical damage may be caused. In particular, if the peak power increased due to unstable oscillation is amplified by the subsequent amplification unit, the peak power further increases and the optical components are damaged.

  Causes of unstable oscillation include unstable spike-like oscillation in the transient state due to on (connected) and off (disconnected) excitation means and parasitic oscillation in the steady state due to reflected light from optical components. Are known.

  Recently, a laser apparatus has been developed that avoids a single spike-like oscillation in a transient state when the excitation means is on and a spike-like oscillation based on a parasitic oscillation in a steady state due to return light (for example, Patent Document 1). reference.).

Japanese Patent Application Laid-Open No. 2004-241531

  The conventional laser device described above avoids a single spike-like oscillation by disposing a mechanical shutter at the laser beam exit of the laser device and blocking the laser beam in a transient state for a certain period of time. In addition, the number of amplifiers in the laser amplification unit is smaller than the number of amplifiers in the laser oscillation unit to avoid steady-state parasitic oscillation.

  In conventional devices that place a mechanical shutter at the laser beam exit, it is possible to prevent spiked laser beams with high peak power from being emitted from the laser device, but optical damage to optical components in the laser device Cannot be avoided. Further, although there is no mention of a transient spike laser beam when the excitation means is off, the mechanical shutter can be operated so as not to be emitted outside. However, as with the spike-like laser light at the time of turning on, damage to the optical components in the laser device cannot be avoided even though it cannot be exposed. In addition, the excitation means may be turned off due to a power failure or disconnection of the power cord while the laser device is operating, but in that case, the shutter cannot be operated, and spike laser light is emitted outside the laser device. End up. Of course, even in this case, optical damage of the optical components in the laser apparatus cannot be avoided.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an optical damage avoidance device that avoids optical damage due to spike-like oscillation associated with on / off of excitation means.

  It is another object of the present invention to provide an optical damage avoidance device that avoids optical damage due to spike-like oscillation caused by turning off excitation means during a power failure or the like.

An optical damage avoidance device for a laser device according to the present invention, which has been made to solve the above-described problems, includes an oscillation unit excitation unit that excites a gain medium of an oscillation unit that is connected to an external power source and performs mode-lock oscillation, and the external power source. Amplifying unit excitation means for exciting the gain medium of the amplifying unit connected to amplify the laser light from the oscillating unit; and connecting the oscillating unit excitation unit and the amplifying unit excitation unit to the external power source and / or the external power source anda connection and disconnection control means for controlling the order to disconnect from the connection-disconnection control means, the oscillating portion excitation means connected to the above at the time of connection, disconnecting the amplifier section excitation means above at the time of cutting It is characterized by doing.

In photodamage avoid the above fitting Symbol Les chromatography The device, the connection-disconnection control means, wherein when connecting to an external power source, and connecting the oscillating portion excitation means previously spiked laser beam generated by the connection After a predetermined time longer than a period of time elapses, the amplification unit excitation unit is connected. When disconnecting from the external power supply, the amplification unit excitation unit is disconnected and then the oscillation unit excitation unit is disconnected. Is.

Also, when the pre-Symbol oscillation unit exciting means is disconnected from the external power source, it may have an auxiliary power is continuously supplied for a predetermined time quantity of electricity to the oscillating unit excitation means.

  In the above optical damage avoidance device, the connection / disconnection control means may include a relay.

  The auxiliary power source may include a capacitor.

  A connection / disconnection control unit that controls the order in which the oscillation unit excitation unit and the amplification unit excitation unit are connected to and / or disconnected from the external power source. ) Is not amplified in the subsequent amplification section, so that the peak power does not increase and optical damage can be avoided. Further, by cutting the amplification unit excitation means first at the time of cutting, the spiked laser beam at the time of cutting (off) is not amplified by the subsequent amplification unit, so that the peak power does not increase and optical damage can be avoided. .

  When the oscillating unit excitation means is disconnected from the external power supply, it has an auxiliary power supply that continues to supply electricity to the oscillating unit excitation unit for a predetermined time. However, since the oscillating unit is substantially cut later, the spiked laser beam at the time of cutting (off) is not amplified by the subsequent amplification unit. As a result, optical damage can be avoided.

  Even if the oscillation unit excitation means and the amplification unit excitation means are disconnected at the same time due to a power failure, etc., if the connection / disconnection means has a relay, the disconnection is automatically detected by the return action of the spring of the relay, and the auxiliary power supply Excitation of the oscillation unit is started.

  When the auxiliary power supply includes a capacitor, the time for exciting the gain medium of the oscillation unit is determined by the capacitance of the capacitor. Therefore, the capacitance of the capacitor may be selected so as to satisfy a predetermined time when the auxiliary power source is excited.

It is a schematic block diagram which shows typically the optical damage avoidance apparatus of the laser apparatus by Embodiment 1 of this invention. 1 is a schematic configuration diagram schematically showing an optical damage avoidance device for a laser apparatus according to Embodiment 1. FIG. It is a schematic block diagram which shows typically the optical damage avoidance apparatus of an Example. It is an operation | movement timing chart figure of the optical damage avoidance apparatus of an Example.

  Embodiments of the present invention will be described in detail with reference to the drawings.

  (Embodiment 1) FIG. 1 is a schematic configuration diagram schematically showing an optical damage avoidance apparatus for a laser apparatus according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the optical damage avoidance apparatus of the present embodiment includes an oscillation unit excitation unit 2 that excites the gain medium 11 of the oscillation unit 1, an amplification unit excitation unit 4 that excites the gain medium 3 of the amplification unit, And a connection / disconnection control unit 5 for controlling the order of connecting the oscillation unit excitation unit 2 and the amplification unit excitation unit 4 to an external power source and / or disconnecting from the external power source.

  The oscillating unit 1 includes a gain medium 11 and resonator mirrors 12 and 13. The gain medium 11 is, for example, an Nd: YAG crystal.

  The gain medium 3 of the amplifying unit is usually the same Nd: YAG crystal when the gain medium 11 is an Nd: YAG crystal.

  The oscillation unit excitation unit 2 includes an excitation light source 21 and a drive unit 22. The excitation light source 21 is, for example, a laser diode. The driving means 22 is a constant current driver that supplies a constant current to the laser diode 21.

  The amplification unit excitation unit 4 includes an excitation light source 41 and a drive unit 42. The excitation light source 41 is a laser diode, and the drive means 42 is a constant current driver.

  The connection / disconnection control means 5 includes a control unit 51, an oscillation unit relay 52, and an amplification unit relay 53. The control unit 51 is, for example, a logic circuit (timing generation circuit). In addition to the logic circuit, an electronic control unit (ECU) composed of a microprocessor centered on a CPU may be used.

  6 is a DC power supply, and 7 is a main switch.

  Next, the operation of the optical damage avoidance apparatus of this embodiment will be described. First, when the main switch 7 is turned on, the DC power source 6 is energized and the logic circuit 51 operates. The logic circuit 51 energizes the coil 52a of the relay 52, the contact piece 52b is attracted to the coil 52a against a spring (not shown), and the relay 52 is turned on. When the relay 52 is turned on, the constant current driver 22 is energized, excitation light from the laser diode 21 excites the Nd: YAG crystal 11, and laser light is emitted from the oscillation unit 1.

  Next, the logic circuit 51 energizes the coil 53a of the relay 53, the contact piece 53b is attracted to the coil 53a against a spring (not shown), and the relay 53 is turned on. When the relay 53 is turned on, the constant current driver 42 is energized, the excitation light from the laser diode 41 excites the Nd: YAG crystal 3, and the laser light from the oscillation unit 1 is amplified by the Nd: YAG crystal 3.

  The above is the operation of the light avoidance device when operating the laser device. As described above, since the oscillating unit 1 is first operated and then the gain medium 3 of the amplifying unit is excited, unstable oscillation at the initial operation of the oscillating unit 1 is not amplified by the gain medium 3 of the amplifying unit. Therefore, optical damage can be avoided.

  When ending the operation of the laser device, the logic circuit 51 stops energization of the coil 53a of the relay 53, the contact piece 53b is attracted by a spring (not shown) and is opened, and the relay 53 is turned off.

  Next, the logic circuit 51 stops energization of the coil 52a of the relay 52, the contact piece 52b is attracted by a spring (not shown) and is opened, and the relay 52 is turned off. Finally, the main switch 7 is turned off and the process ends.

  As described above, when the operation of the laser device is terminated, the excitation of the gain medium 3 of the amplifying unit is stopped first, and then the oscillating unit 1 is stopped. The oscillation is not amplified by the amplification unit. Therefore, optical damage can be avoided.

  When the control unit 51 is a logic circuit as described above, the control is sequentially performed in the order of relay 52 on → relay 53 on → relay 53 off → relay 52 off.

  (Embodiment 2) FIG. 2 is a schematic configuration diagram schematically showing an optical damage avoidance apparatus for a laser apparatus according to Embodiment 2 of the present invention. The optical damage avoidance apparatus according to the present embodiment is the same as the optical damage avoidance apparatus according to the first embodiment except that the auxiliary power supply 8 including a capacitor is provided between the relay 52 and the oscillation unit excitation unit 2. Same as the device. The same components are denoted by the same reference numerals, and description thereof is omitted.

  The operation when a power failure occurs during operation of the laser device will be described below.

  When the laser device is in an operating state, since the relay 52 is on, the constant current driver 22 is energized and at the same time the capacitor of the auxiliary power supply 8 is charged.

  When a power failure occurs, the relay 52 and the relay 53 are simultaneously turned off, and energization of the constant current driver 22 and the constant current driver 42 from the DC power supply 6 is simultaneously turned off. However, since the amount of electricity stored in the capacitor of the auxiliary power supply 8 continues to be supplied to the constant current driver 22 even when the relay 52 is turned off, the oscillation unit 1 continues to oscillate for a while after a power failure. When the capacitor is emptied, the oscillation stops. However, since the excitation of the amplifying unit is stopped before that, unstable oscillation when the oscillation is stopped is not amplified by the amplifying unit. As a result, optical damage is avoided.

  FIG. 3 is a schematic configuration diagram of an optical damage avoidance device of the mode-locked fiber laser device. FIG. 4 is an operation timing chart of the optical damage avoidance apparatus according to the embodiment.

  As shown in FIG. 3, the optical damage avoidance apparatus according to the present embodiment includes an oscillation unit excitation unit 2 that excites the gain medium 11A of the oscillation unit 1, an amplification unit excitation unit 4 that excites the gain medium 3A of the amplification unit, A connection / disconnection control unit 9 for controlling the order of connecting the oscillation unit excitation unit 2 and the amplification unit excitation unit 4 to an external power source and / or disconnecting from the external power source, and an auxiliary power source 8 are provided.

  The gain medium 11 </ b> A is an Er-doped fiber, and excitation light from the laser diode 21 is coupled via the fiber coupler 14. 12A is a saturable absorber mirror.

  The gain medium 3 </ b> A of the amplifying unit is also an Er-doped fiber, and the excitation light from the laser diode 41 is coupled via the fiber coupler 31.

  The laser diodes 21 and 41 are general butterfly type laser diodes.

  As the constant current drivers 22 and 42 for driving the laser diodes 21 and 41, for example, those manufactured by US Wavelengths or Tolabor may be used. Since the laser diodes 21 and 41 have a maximum current of 1A class, the constant current drivers 22 and 42 only need to be able to flow more current.

  The connection / disconnection control means 9 includes a timing generation circuit 91, a power relay 92 having a single-pole double-throw contact, and a normal relay 93. The operation time of the contact pieces 92b and 93b of the relays 92 and 93 is about 30 to 50 ms.

  Relay coils 92a and 93a of relays 92 and 93 are connected to timing generation circuit 91 and driven as shown in the timing chart of FIG.

  A contact point NO (normally off) of the relay 92 is connected to the constant current driver 22, and is branched to the capacitor 8 via the resistor R1 and joined via the resistor R2 on the way.

  The capacitor 8 is connected to the contact NC (normal contact) of the relay 92 via the resistor R1 and the diode D1. The diode D1 is arranged to prevent the amount of electricity charged in the capacitor 8 from flowing back to the DC power source 6 when the AC 100v is cut off.

  The capacity of the capacitor 8 may be a value that allows energization for 300 ms with a CR time constant of 150 ms and a margin of twice.

  Next, the operation will be described with reference to the timing chart of FIG.

  When the main switch 7 is turned on, AC 100v is energized to the DC power source 6 and an output voltage is generated. Since power is also supplied to the timing generation circuit 91 at the same time, drive signals for the relay 92 and the relay 93 are output, and the relay 92 and the relay 93 operate at the following timing. That is, at the same time as the output voltage of the DC power supply 6 is generated, the contact piece 92b of the relay 92 switches from the contact NC to the contact NO against a spring (not shown) (the switching time is about 30 ms).

  Then, the driver 22 is energized and supplies a predetermined current to the laser diode 21. Further, when the contact piece 92b of the relay 92 is switched from the contact NC to the contact NO against a spring (not shown), the driver 8 and the laser diode 21 are charged while charging the capacitor 8 as the auxiliary power source via the resistor R1. Drive.

  When the laser diode 21 is driven, the excitation light from the laser diode 21 is coupled to the Er-doped fiber 11A via the coupler 14, and the laser oscillates. Spike-like oscillation occurs for about 50 ms from when the mode lock is applied until stable mode lock oscillation occurs. This 50 ms is a period in which there is a high possibility of causing optical damage. This period is determined by the characteristics of the optical system of the oscillator 1.

  Next, when 80 ms elapses after the main switch 7 is turned on, the timing generating circuit 91 drives the contact piece 93 against a spring (not shown), turns on the relay 93, and drives the driver 42 and the laser diode 41. Is done.

  Since the laser diode 41 is driven after the end of the spike-like oscillation, the spike-like oscillation is not amplified by the Er-doped fiber 3A of the amplification unit. As a result, optical damage is avoided. That is, as described above, when AC 100 v power is supplied, the optical oscillator operates in the order of the first-stage oscillation unit 1 → the subsequent-stage amplification unit, so that optical damage does not occur. Further, the operation of the laser device when AC 100v power is supplied is operated in the order of relay 53 OFF → relay 52 OFF, and the power supply is turned OFF in the order of driver 42 → driver 22. Optical damage due to spike oscillation can be avoided.

  Next, the operation when the AC 100v power is not supplied due to a power failure or the like while the main switch 7 is on and the laser device is operating will be described.

  When a power failure occurs at the time of the arrow, the DC power supply 6 goes down and the output voltage becomes zero. At the same time, power is not supplied to the timing generation circuit 91, and the energization of the relay coils 92a and 93a is stopped. Then, the contact piece 92b is switched to the contact NC side by a return action of a spring (not shown). Similarly, the contact piece 93b is driven by a return action of a spring (not shown), and the relay 93 is turned off.

When a power failure occurs, power to the driver 42 is turned off instantaneously regardless of whether the relay 93 is on or off, and the laser diode 41 also stops instantaneously. On the other hand, when a power failure occurs, power is supplied from the DC power supply 6 to the driver 22. However, since the amount of electricity charged in the capacitor 8 is supplied to the driver 22, the output of the laser diode 21 lasts for about 150 ms.

  When the laser diode 21 stops, spike-like oscillation occurs. However, since the laser diode 41 stops before that as described above, the spike-like oscillation is not amplified by the Er-doped fiber 3A of the amplifying unit. . As a result, optical damage is avoided.

DESCRIPTION OF SYMBOLS 1 .... Oscillation part 11 ... Gain medium 2 ... Oscillation part excitation means 3 ... Gain medium 4 of amplification part ... Amplification part excitation means 5 .... Connection / disconnection control means

Claims (5)

Oscillating unit excitation means for exciting a gain medium of an oscillating unit that is connected to an external power source and mode-locked oscillating ;
Amplifying unit excitation means for exciting the gain medium of the amplifying unit connected to the external power source and amplifying the laser light from the oscillating unit;
Connection / disconnection control means for controlling the order of connecting the oscillation unit excitation unit and the amplification unit excitation unit to the external power source and / or disconnecting from the external power source, and
The apparatus for avoiding optical damage of a laser device, wherein the connection / disconnection control unit connects the oscillation unit excitation unit first when connected, and disconnects the amplification unit excitation unit first when disconnected. The connection / disconnection control unit connects the oscillation unit excitation unit first when connecting to the external power source, and after the elapse of a predetermined time longer than a period in which spiked laser light is generated by the connection, the amplification unit The optical damage avoidance device for a laser device according to claim 1, wherein when the excitation unit is connected and disconnected from the external power source, the oscillation unit excitation unit is disconnected after the amplification unit excitation unit is disconnected. When the pre-Symbol oscillation unit exciting means is disconnected from the external power source, photodamage avoidance device of a laser apparatus according to claim 1 or 2 having an auxiliary power source is continuously supplied for a predetermined time quantity of electricity to the oscillating unit excitation means . 4. The optical damage avoidance device for a laser device according to claim 1, wherein the connection / disconnection control unit includes a relay. 5. The optical damage avoidance device for a laser device according to claim 3 , wherein the auxiliary power source includes a capacitor.

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