Frugal system for generating laser pulses

Abstract

The present invention relates to a system (100) for generating laser pulses comprising a laser (10), a power supply (11) and a control system (6). According to the invention, the system (100) for generating laser pulses is configured to cyclically generate a packet of laser pulses with a duty cycle defined by a ratio between an activity duration (T1) when the system for generating laser pulses emits the packet of laser pulses and a cycle duration (T2), each laser pulse having a duration less than or equal to 100 nanoseconds, wherein the activity duration (T1) is less than a duration of thermal stabilization of the laser and the control system (6) is configured to actuate or stop the power supply (11) so as to limit the duty cycle of the system (100) for generating laser pulses to a maximum value of 50%, and preferably to 30%, 10% or 1%.

Description

Frugal laser pulse generation system Technical field of the invention

[0001] The present invention relates to the technical field of laser pulse generation systems.

[0002] In particular, it relates to a system for generating laser pulses of sufficiently high peak power for industrial or medical applications while having low electrical energy consumption. State of the art

[0003] Short laser pulses (lasting less than or equal to 100 nanoseconds (ns)) or ultrashort laser pulses (lasting less than or equal to 1 ns) with energy between 100 nJ and 10 mJ are highly sought after for a wide variety of applications such as marking, micromachining or eye surgery.

[0004] Figure 1 schematically illustrates the simplified architecture of a system for generating short or ultrashort laser pulses according to the prior art. The laser pulse generation system generally comprises a power supply unit 1, a laser 10 or optical amplifier, a control system 2 connected to an optical modulator or to a shutter, noted 3 in Figure 1. The power supply unit 1 delivers a generally alternating current 20, which supplies in particular a source oscillator and pumping diodes of the laser 10. The optical modulator or the shutter 3 is arranged at the output of the laser 10, between the laser 10 and the target 4 of the laser treatment, that is to say the sample or the patient intended to receive the treatment by laser pulses. The laser 10 is here configured to generate short laser pulses 30.Short or ultrashort laser pulses are generally emitted at a specific repetition frequency, for example between 10 Hz and 10 MHz in single-pulse mode, or even a few GHz in burst mode.

[0005] Like most laser pulse generation systems used for industrial or medical applications, the system in Figure 1 has a generic operating mode that consists of emitting laser pulses continuously, at a determined repetition frequency and modulating the emitted beam according to the user's needs. For this purpose, the system control 2 is adapted to actuate the optical modulator or shutter 3 so as to modulate the intensity of the laser pulse beam emitted by the laser 10 at the target 4. The combination of the control system 2 and the optical modulator or shutter 3 thus makes it possible to allow the emitted laser pulse beam 30 to pass or to block it. The control system 2 can be actuated by a user via a pedal or a button or a computer application on a computer.

[0006] This operating mode makes it possible to achieve the stationary thermal regime of the laser 10 and to guarantee a relatively stable emission of laser pulses regardless of the actual duration of use. In this document, we call this operating mode the continuous mode or continuous regime. The laser 10 emits radiation continuously but the laser pulse beam 30 is only delivered for the desired use when the user needs it thanks to the control system 2 external to the laser 10. The target 4 receives, for example, packets of light pulses for a limited duration while the laser continuously emits laser pulses with a determined repetition frequency. This operating mode makes it possible to meet the current needs of the user.The laser pulses blocked by the optical modulator or by the shutter 3 are, for example, absorbed by the material of the optical modulator or of the shutter 3 or deflected out of the optical path towards an absorbing medium.

[0007] However, prior art systems for generating short or ultrashort laser pulses are relatively complex. Indeed, the laser components are sized to be able to operate in continuous mode. These systems require a modulator or shutter 3 capable of blocking the laser pulses without being damaged. In addition, it is necessary to achieve the steady-state thermal regime so that the performance does not vary over time, which necessarily takes a time greater than that of thermal diffusion in the system, generally more than one minute and up to 30 minutes. Heat dissipation in the laser or optical amplifier generally requires the provision of an active cooling system. Continuous use of the components generates wear and high operating costs. Overall, the efficiency The overall energy consumption of such a system for generating short or ultrashort laser pulses is very low.

[0008] It is desirable to improve the energy efficiency of a system for generating short or ultrashort laser pulses. It is also desirable to improve the lifetime of the components of such a system. In other words, it is desirable to reduce the operating costs of a laser pulse generation system. In addition, it is desirable to reduce the size of such a laser pulse generation system. Finally, it is desirable to operate a system for generating short or ultrashort laser pulses autonomously, without connection to the electrical network. Presentation of the invention

[0009] In this context, the present invention provides a laser pulse generation system comprising a laser, a power supply system and a control system, the power supply system being adapted to electrically power the laser.

[0010] More particularly, the invention proposes a laser pulse generation system adapted to cyclically generate a packet of laser pulses with a cycle duration (T2) and a duty cycle defined by a ratio between an activity duration (T1) where the laser pulse generation system emits the packet of laser pulses and the cycle duration (T2), the cycle duration (T2) being equal to the sum of the activity duration (T1) and a rest time where the laser pulse generation system does not emit any laser pulse, each laser pulse having a duration less than or equal to 100 nanoseconds, in which the activity duration (T1) is less than a thermal stabilization duration of the laser and the control system is configured to actuate or stop the power supply system so as to limit the duty cycle of the laser pulse generation system to a maximum value of 50%.

[0011] Thus, the system can generate high peak power laser pulses while drastically limiting its power consumption, forming a frugal or energy-efficient laser system. In addition, this avoids the use of complex active cooling systems. The system can be sized according to the desired application and not according to the maximum requirements imposed by continuous operation.

[0012] Other non-limiting and advantageous characteristics of the system according to the invention, taken individually or in all technically possible combinations, are as follows.

[0013] Advantageously, the activity duration (T1) is less than or equal to ten seconds.

[0014] According to a particular and advantageous aspect, the control system comprises an electronic device and / or a digital system comprising a processor and control software.

[0015] According to an exemplary embodiment, the laser pulse generation system comprises a user interface device connected to the control system, the user interface device being adapted to transmit a switching signal to the control system to operate or stop the power supply system.

[0016] Advantageously, the duration of the laser pulses is between 50 fs and 100 ns, and the packet of laser pulses has a repetition frequency between pulses of a packet greater than or equal to 1000 hertz.

[0017] In an exemplary embodiment, the laser comprises an oscillator capable of generating source pulses, an optical amplifier system comprising at least one optical amplifier medium, an optical pumping device electrically powered by the power supply system, the optical pumping device comprising at least one laser diode, the optical pumping device being configured to optically pump the oscillator and the optical amplifier system, the control system and the power supply system being configured to electrically switch the optical pumping device.

[0018] According to a particular and advantageous aspect, the laser pulse generation system comprises a cooling device, the cooling device being arranged to cool said at least one optical amplifying medium and / or the oscillator and / or the optical pumping device.

[0019] Advantageously, the laser pulse generation system comprises a thermal regulation device arranged so as to regulate the temperature of the oscillator, the optical pumping device and / or said at least one optical amplifier medium of the laser pulse generation system.

[0020] In an exemplary embodiment, the optical pumping device comprises a pumping laser diode of the oscillator, and at least one pumping laser diode of said at least one optical amplifying medium, and the control system is configured to control the power supply system so as to sequentially activate or stop the pumping laser diode of the oscillator and said at least one pumping laser diode of said at least one optical amplifying medium.

[0021] Preferably, the control system is configured to operate or stop the power supply system so as to limit the duty cycle of the laser pulse generation system to a maximum value of 30%, 10% or 1%.

[0022] For example, the electrical power system comprises at least one electrical battery, the electrical power system being configured to generate a direct electrical current, for example at a voltage of 24 volts.

[0023] Of course, the various features, variants and embodiments of the invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive. Brief description of the drawings

[0024] In addition, various other characteristics of the invention emerge from the appended description given with reference to the drawings which illustrate non-limiting embodiments of the invention and where:

[0025] Figure 1 is a schematic view of a laser pulse generation system according to the prior art;

[0026] Figure 2 is a schematic view of an architecture of a laser pulse generation system according to the present disclosure;

[0027] Figure 3 is a schematic view of an exemplary implementation of a laser pulse generation system according to the present disclosure;

[0028] Figure 4 is a diagram illustrating the activity time and rest time over the duration of a duty cycle;

[0029] Figure 5 is a curve schematically illustrating the evolution of the laser temperature during a usage cycle.

[0030] It should be noted that in these figures the structural and / or functional elements common to the different variants may have the same references. Detailed description

[0031] The present disclosure provides a system for generating short or ultrashort laser pulses having an architecture and operation radically different from the prior art.

[0032] Figure 2 schematically represents a laser pulse generation system 100 according to the present disclosure. The laser pulse generation system 100 comprises a power supply system 11, a laser 10 comprising one or more optical amplifiers and a control system 6. By way of non-limiting example, the laser pulse generation system 100 comprises an electrical switch device 5 arranged between the control system 6 and the power supply system 11, the electrical switch device 5 being electrically connected at the input to the control system 6 and at the output to the power supply system 11.

[0033] More particularly, the control system 6 is here connected to the electrical power supply system 11. The control system 6 is configured to actuate or stop the electrical power supply system 11. The electrical power supply system 11 comprises a power supply unit connected to the electrical network or a rechargeable autonomous electric battery. The electrical power supply system 11 delivers an alternating or direct electrical current 21 which is controlled by the control system 6. The electrical current 21 is supplied to the laser 10.

[0034] The 10 laser is based on the use of one or more laser amplifiers. These amplifiers can use gain media in the form of doped crystals, doped glasses, doped fibers or any other laser device allowing a light signal to be amplified.

[0035] As detailed in Figure 3, the laser 10 comprises for example an oscillator 13, an optical pumping device 12, an optical preamplifier 14, at least one optical amplifier 15 and possibly a temporal and / or spatial shaping device 16. Optionally, the laser 10 comprises a cooling device 7 and / or a thermal regulation device 8. The cooling device 7 is arranged to cool the oscillator and / or the optical preamplifier and / or the optical amplifier(s) 15 and / or the temporal and / or spatial shaping device 16 and / or the optical pumping device 12. The thermal regulation device 8 is arranged to stabilize the temperature of the oscillator and / or the optical preamplifier and / or the optical amplifier(s) 15 at a predetermined set temperature.Advantageously, the laser pulse generation system 100 comprises a user interface device 9 connected to the control system 6.

[0036] The optical pumping device 12 comprises, for example, pumping diodes adapted to optically pump the source oscillator 13, the optical preamplifier 14 and the optical amplifier 15 of the laser 10. The optical pumping device 12 is electrically powered by the electrical power supply system 11 which comprises one or more sources of electrical current.

[0037] In known manner, the oscillator 13 emits source pulses. The optical preamplifier 14 receives the source pulses and generates preamplified pulses. The at least one optical amplifier 15 receives the preamplified pulses and forms amplified pulses. The temporal and / or spatial shaping device 16 temporally and / or spatially shapes the amplified pulses. The temporal and / or spatial shaping device 16 comprises, for example, a compressor for temporally compressing the amplified pulses. The laser 10 thus generates a beam 31 of short or ultrashort laser pulses. Advantageously, the laser pulses have a duration less than or equal to 1 nanosecond, and preferably less than or equal to 100 picoseconds (ps), and even more preferably less than or equal to 1 picosecond, for example between 50 femtoseconds (fs) and 1 picosecond.

[0038] The electrical power supply system 11 delivers an electrical current 21 which supplies the laser 10, and more particularly, the optical pumping device 12. If necessary, the electrical power supply system 11 also supplies the thermal regulation device 8.

[0039] We will now describe the operation of the laser pulse generation system 100 according to the present disclosure. The control system 6 controls the power supply system 11 so as to directly modulate the power supply of the laser 10 or at least a part of the laser 10. As schematically illustrated in FIG. 4, the laser 10 is only electrically powered during a usage time T1, also called the activity time, with a repetition period T2, also called the cycle time. In other words, the laser 10 is not electrically powered during the time interval T2-T1. The activity time T1 is generally short and, in any case, less than the thermal stabilization time of the laser. It follows that the laser 10 only generates laser pulses during the activity time T1 with a repetition period T2.

[0040] By way of non-limiting example, the electrical power supply system 11 directly modulates the power supply of the optical pumping device 12 with the activity duration T1 and the repetition period T2. The gain of the preamplifier 14 or of the amplifier 15 is directly linked to the power emitted by the pumping diode(s) and consequently to the electric current supplying these diodes. When the electric current supply to the pumping diodes is stopped, the gain of the preamplifier 14 or of the amplifier 15 becomes zero and no laser emission 33 is observed at the output of the system 100. Conversely, as soon as the pumping diodes are supplied with electric current, a packet of laser pulses 32 is observed at the output of the system 100. This operating mode is here called pulsed mode.

[0041] The control system 6 comprises an electronic circuit or is connected to a mechanical switch which controls the electrical power supply system 11. For example, the control system 6 generates a logic activation signal which controls the electrical power supply of the pumping diodes. When the control signal is present, the pumping diodes are electrically powered and the system 100 emits laser radiation 32. Conversely, when the control signal is interrupted, the pumping diodes are no longer powered. electrically and the system 100 no longer emits laser radiation 33. In this case, the control system 6 is configured to control the electrical power supply system 11 by all or nothing. Alternatively, the control system 6 is configured to control the electrical power supply system 11 so as to switch the power supply of a portion of the pumping diodes, for example the pumping diodes of the amplifier(s) 14, 15.

[0042] Optionally, the control system 6 is configured to provide several activation signals whose time distribution is designed to ensure optimal starting and stopping of the laser 10. For example, it may be advantageous to sequentially turn on the pump diodes, starting with those of the oscillator 13, then those of the preamplifiers 14, and ending with those of the amplification stages 15 furthest downstream in the amplification chain. Similarly, upon switching off, it is advantageous to start by interrupting the power supply to the pump diodes of the amplifiers 15 through which the laser pulses last pass, and ending with the pump diodes of the oscillator 13. The time elapsed between the switching on of the first and last amplification stages is then very small compared to the duration T1 of a packet of short or ultrashort laser pulses.Such sequencing makes it possible to avoid an accumulation of energy (i.e. excited population) in the amplifiers 15 which is likely to be transmitted in one go to the first pulse of the oscillator which passes through them, giving rise to a first giant pulse which generally destroys the amplifier. Such a sequence only appears once in continuous operation but it is here repeated at each switching on and off in the pulsed mode of operation according to the present disclosure.

[0043] Optionally, the user interface device 9 connected to the control system 6 makes it possible to directly activate the power supply system. Advantageously in this case, the control device 6 is configured to automatically stop the power supply after a determined duration (for example T1). The user interface device 9 comprises, for example, a push button or a pedal for triggering and / or stopping the laser emission. Alternatively, the user interface device 9 comprises a computer application or an electronic card producing pre-recorded sequences.

[0044] Consider a laser pulse generation system 100 that emits laser pulses of short duration, less than 100 ns, at a rate greater than 1 kHz, in packets of duration T1 with a packet repetition period T2. The packet of duration T1 emits an average light power P1. This average light power P1 is defined as the sum of the energies of the pulses emitted during the packet divided by the duration T1 of the packet. P1 is the light power actually used by the end user during a time T1 with a periodicity T2. The duty cycle of use is here equal to T1 / T2.

[0045] The light energy actually used by the user in the intended application is equal to E1 = P1*T1. On the other hand, the energy used to operate the laser pulse generation system 100 depends on its operating mode. We note r the efficiency of the electrical power supply system 11.

[0046] In pulsed mode, the system is only powered during the time T1 of use. The energy consumed during a cycle is equal to Ec1 = E1 / r.

[0047] On the contrary, in continuous mode, the system is powered for the entire duration of a cycle T2 and the laser beam is interrupted at the output of the laser system to be used only during time T1. In this continuous mode, the energy consumed to be able to produce the power P1 is equal to Ec2=E2 / r=P1*T2 / r regardless of the duration of use T1. The ratio between the energy used and the energy consumed is therefore Ec1 / Ec2 which is equal to the duty cycle T1 / T2. It can be seen that the electrical energy consumption in continuous mode Ec2 is much higher than the energy used by the duration of activity T1.

[0048] However, in some applications, the duty cycle can be much lower than 1 / 10. In these applications, the continuous mode laser pulse generation system consumes at least 10 times more energy than the user uses.

[0049] Here we are particularly interested in certain applications, in which the duration of T1 use is very short. For example, a laser system for a surgical procedure to cut the lens capsule is used for less than ten seconds (e.g. 4s) and the time between two interventions is generally several minutes, for example every 15 minutes. In the field of industrial applications, an industrial laser system for matrix data marking is used for 100 ms every 3 seconds. As seen in these two applications, the duration of T1 use is very short compared to the thermal stabilization time of the laser system 10 which is at least one minute and can reach 30 minutes.

[0050] According to the present disclosure, the laser pulse generation system 100 is not only configured to control the laser power supply system 10, but it is also sized according to the desired application so as to reduce the energy consumption of the system 100 or to improve the energy efficiency of the short or ultrashort laser pulse generation system 100.

[0051] More particularly, the usage time T1 and the rest time T2-T1 of the laser pulse beam are determined during a cycle. The peak power P1 required for the application during the usage time T1 is determined. The architecture of the laser 10 is adapted to enable the peak power P1 to be obtained during the duration T1, with a repetition period T2. The control system 6 is configured so as to electrically power the laser 10 during the duration T1 and to interrupt the electrical power supply to the laser 10 during the rest time T2-T1. Advantageously, the cooling device 7 is sized and configured so as to enable the evacuation of an energy Ec1 = P1*T1 / r. The electrical power supply system 11 is sized so that the laser 10 provides the peak power P1 during the duration T1 with an average power equal to P2=P1.T1 / T2.The control system 6 is configured to trigger the power supply of the laser 10 either manually via a pedal or a push button, or automatically via a programmed electronic circuit. The control system 6 is also configured to interrupt the power supply of the laser 10, either manually via a pedal or a push button, or automatically via a programmed electronic circuit. The duration of the power supply of the laser 10 is limited by an electronic card to half the duration of a cycle, in other words the duty cycle T1 / T2 is less than 50%. Depending on the applications, the duty cycle T1 / T2 is limited to 30%, 10% or 1%. This gives the cycle duration T2. ​​Advantageously, the cooling device 7 is sized and configured so that the temperature of the laser 10 returns to the initial temperature after a duration less than T2 corresponding to an operating cycle.

[0052] The cooling device 7 comprises, for example, a passive conduction cooling device, a passive convection cooling device or an air cooling device, for example a fan.

[0053] Advantageously, a thermal regulation device 8 is used to stabilize the temperature of the laser 10, including the oscillator 13 and more precisely the pumping diodes 12 of the oscillator and the amplifiers, before the laser power supply is triggered. This thermal regulation device 8 is used to ensure that the trigger point is always the same. This thermal regulation device 8 comprises, for example, an element operating by the Peltier effect arranged so that the temperature of one or more components of the laser 10 is equal to or close to a set temperature T0 at the time when the power supply is triggered.

[0054] Figure 5 schematically illustrates a curve 24 of the temperature of the laser 10 as a function of time. The curve 24 results from a simulation at the base of a pumping laser diode 12. The laser pulse generation system operates here in pulsed mode, with cyclic use for a duration T1 with a cycle duration T2. ​​At the start of a cycle, the temperature of the laser is equal to the set temperature T0. As illustrated in Figure 5, during the emission of a packet of laser pulses of duration T1, the temperature of the laser 10 does not have time to change significantly and the operation of the laser pulse generation system 100 is reproducible. During the rest time of duration T2-T1, between two packets of laser pulses, the temperature of the laser 10 increases up to a maximum Tmax then gradually drops back to its set temperature T0.As a reminder, the laser thermal stabilization time corresponds to the time during which the laser reaches a stable temperature in continuous operation. The laser thermal stabilization time is therefore greater than the time between the start of the cycle and the instant at which the temperature Tmax is reached, since the laser emission is interrupted after the time T1 in pulsed operation.

[0055] It is observed that the laser pulse generation system 100 of the present disclosure operates outside the stationary thermal regime where the temperature is constant. Nevertheless, the short operating time T1 and the low duty cycle T1 / T2 make it possible to operate in a relatively stable and reproducible regime.

[0056] In addition, the Tmax temperature is lower than the laser's thermal stabilization temperature in continuous operation. The Tmax temperature remains limited, which allows the use of a passive cooling device or an inexpensive and space-saving air cooling device. For example, for a duty cycle less than or equal to 30%, the Tmax temperature remains below 50°C.

[0057] The thermal power dissipated by the laser pulse generation system 100 of the present disclosure is estimated as follows. The energy required to operate the laser pulse generation system 100 is defined by Ec1=E1 / r= P1.T1 / r

[0058] The electrical energy used is broken down into two terms: the energy E1 used to generate the laser pulses and the energy E1T which is dissipated thermally.

[0059] Ec1 =E1 +E1T

[0060] The thermally dissipated energy E1T is expressed as a function of the efficiency r of the system 100: E1T=E1(1-r).

[0061] When the efficiency r is low, most of the energy is dissipated as heat. For a laser pulse generation system 100 producing laser pulses with a duration of less than 1 ns, the efficiency r does not exceed 30% and can be less than 10% for very short pulses. The majority of the energy consumed is therefore transformed into heat.

[0062] By comparison, in the case of a conventional laser pulse generation system operating in continuous mode, the energy required to operate such a system is Ec2=E2 / r= P1,T2 / r and the thermally dissipated energy is equal to E1T=E2(1-r)= E1T.T2 / T1. The heat dissipated in a conventional laser pulse generation system operating in continuous mode is therefore increased by a factor T2 / T1 compared to the laser pulse generation system operating in pulsed mode according to the present disclosure. For example, a medical laser system is used for a duration T1 of 4s for a surgery that can be repeated with a period T2 of 15 min, which corresponds to a ratio T2 / T1 =225. Similarly, an industrial laser matrix data marking system is operated for a T1 duration of 100 ms with a T2 cycle period of 3 s, which corresponds to a T2 / T1 ratio of 30.In a laser pulse generation system operating in pulsed mode according to the present disclosure, the. heat dissipation is therefore 225 times lower in the first example and 30 times lower in the second example, compared with a continuously powered laser.

[0063] The laser pulse generation system operating in pulsed mode of the present disclosure therefore makes it possible to significantly limit the energy consumption which is dissipated thermally. This limitation of energy consumption offers numerous advantages. First of all, it makes it possible to limit the costs linked to electrical consumption. The drastic reduction in heat dissipation in the laser 10, by a factor greater than 10 and which can reach several hundred, makes it possible to avoid the use of a powerful active cooling system which is itself a source of complexity and energy consumption. In addition, the optical and electronic components can be undersized compared to components sized to withstand continuous mode operation.Finally, the reduction in the overall power consumption of the laser pulse generation system 100 makes it possible to use a battery-operated power supply system 11 while maintaining sufficient autonomy for an industrial or medical application. The use of a battery instead of a connection to the electrical network makes handling the laser pulse generation system 100 of the present disclosure much easier and more mobile. An operator or a robot manipulator arm can more easily move the laser pulse generation system 100 according to the present disclosure, which is also more compact. The low-intensity use of the components of the laser 10 increases the lifetime of the laser pulse generation system 100. This low-intensity use also allows the use of components with a shorter lifetime, which are less expensive than components sized for continuous operation.

[0064] We now describe an exemplary embodiment according to the present disclosure. A picosecond laser pulse generation system 100 comprises an oscillator 13 producing source pulses having a duration of 50 ps at a rate of 20 MHz. A modulator disposed downstream of the oscillator decreases the rate of the pulses by a fixed number, for example 40, to provide a source pulse train at the rate of 500 kHz. The oscillator 13 comprises a laser cavity which is optically pumped by a 300 mW pump diode. The The pump diode is electrically powered by a current-stabilized power supply 11. A control box 6 generates an activation signal to trigger or stop the power supply 11 of the oscillator pump diode. When the activation signal of the oscillator is equal to 5V, the power supply 11 immediately produces an electric current 21. The oscillator 13 and the modulator are followed by a fiber preamplifier 14 pumped by a pump diode producing an average power of 2W and then by a fiber amplifier 15 pumped by a pump laser diode with a power of 20W. The electric current supplies of the pump diodes of the optical amplifier system are controlled by another activation signal from the control box 6.This control box 6 comprises for example a pedal to trigger the laser emission and a counter which automatically stops the laser emission after a duration T1, for example 4s. This picosecond laser pulse generation system 100 produces laser pulses at a rate of 500 kHz with an average power of 6W. The picosecond laser pulse generation system 100 is designed to produce pulse packets with a duration T1 of 4s, reproducing on demand with a minimum duration T2-T1 of 10 minutes between two packets. The electrical / optical efficiency (ratio between the electrical energy consumed and the light energy produced) of the pumping diodes is of the order of 40%. The laser itself has an efficiency of 6W / 22W or 27% typical of this type of picosecond laser. The total efficiency of the system is therefore approximately 11%. The average electrical power consumed if the system operates 4s every 10 min is given by Pelec=0.3 W with a peak during the 4s of use and no power during the rest of the cycle. This average power along the cycle is lower than the light power measured during the emission of the packet since the system is essentially unused during the entire cycle except for this short duration T1 of emission of the packet. This picosecond laser pulse generation system 100 of the present disclosure therefore produces sufficient light power for the intended application (for example here a surgical intervention) but only during the time of this use, namely the time T1 of the light packet.

[0065] The thermal load averaged over a cycle of duration T2 is very low since the average power consumed is only 300 mW and the power dissipated heat roughly equal to (1-r) or 90% of this value. This system 100 can therefore be passively cooled thanks to the exchange with the ambient air and can operate on batteries with an autonomy easily exceeding the day.

[0066] The present disclosure finds numerous applications for the use of short or ultrashort pulse lasers with limited or frugal electricity consumption, while making it possible to generate short or ultrashort laser pulses having an average light power greater than or equal to 1 watt, these laser pulses being relatively stable within a package and reproducible from one package to another.

[0067] In particular, the present disclosure finds very varied applications in laser marking, laser micromachining or eye surgery using short or ultrashort pulse lasers.

Claims

Claims 1. A laser pulse generation system (100) comprising a laser (10), a power supply system (11) and a control system (6), the power supply system (11) being adapted to electrically power the laser (10), the laser pulse generation system (100) being adapted to cyclically generate a packet of laser pulses with a cycle duration (T2) and a duty cycle defined by a ratio between an activity duration (T1) where the laser pulse generation system emits the packet of laser pulses and the cycle duration (T2), the cycle duration (T2) being equal to the sum of the activity duration (T1) and a rest time where the laser pulse generation system does not emit any laser pulses, each laser pulse having a duration less than or equal to 100 nanoseconds,wherein the activity duration (T1) is less than a thermal stabilization duration of the laser and the control system (6) is configured to operate or stop the power supply system (11) so as to limit the duty cycle of the laser pulse generation system (100) to a maximum value of 50%., 2. Laser pulse generation system (100) according to claim 1 wherein the activity duration (T1) is less than or equal to ten seconds.

3. A laser pulse generation system (100) according to claim 1 or 2 wherein the control system (6) comprises an electronic device and / or a digital system comprising a processor and control software.

4. Laser pulse generation system (100) according to one of claims 1 to 3 comprising a user interface device (9) connected to the control system (6), the user interface device (9) being adapted to transmit a switching signal to the control system (6) to operate or stop the power supply system (11).

5. Laser pulse generation system according to one of claims 1 to 4 wherein the duration of the laser pulses is between 50 fs and 100 ns, and wherein the packet of laser pulses has a repetition frequency between pulses of a packet greater than or equal to 1000 hertz.

6. Laser pulse generation system (100) according to one of claims 1 to 5 wherein the laser (10) comprises an oscillator (13) capable of generating source pulses, an optical amplifier system comprising at least one amplifier medium optical (14, 15), an optical pumping device (12) electrically powered by the power supply system (11), the optical pumping device (12) comprising at least one laser diode, the optical pumping device (12) being configured to optically pump the oscillator (13) and the optical amplifier system (14, 15), wherein the control system (6) and the power supply system (11) are configured to electrically switch the optical pumping device (12).

7. A laser pulse generation system (100) according to claim 6 comprising a cooling device (7), the cooling device (7) being arranged to cool said at least one optical amplifying medium (14, 15) and / or the oscillator (13) and / or the optical pumping device (12).

8. A laser pulse generation system (100) according to claim 6 or 7 comprising a thermal regulation device (8) arranged to regulate the temperature of the oscillator (13), the optical pumping device (12) and / or said at least one optical amplifier medium (14, 15) of the laser pulse generation system.

9. Laser pulse generation system (100) according to one of claims 6 to 8, wherein the optical pumping device (12) comprises a laser diode (112) for pumping the oscillator, and at least one laser diode for pumping said at least one optical amplifier medium, and wherein the control system (6) is configured to control the electrical power supply system (11) so as to sequentially actuate or stop the laser diode for pumping the oscillator and said at least one laser diode for pumping said at least one optical amplifier medium (14, 15).

10. The laser pulse generation system (100) according to one of claims 6 to 8, wherein the control system (6) is configured to operate or stop the power supply system (11) so as to limit the duty cycle of the laser pulse generation system (100) to a maximum value of 30%, 10% or 1%.

11. Laser pulse generation system (100) according to one of claims 1 to 10 wherein the electrical power supply system (11) comprises at least one electrical battery, the electrical power supply system (11) being configured to generate a direct electrical current.

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