CN103779773B - Laser equipment and control method thereof - Google Patents

Abstract

The present invention relates to laser equipment and control method thereof.Provide a kind of laser equipment, comprising: cavity, there is outgoing mirror and reflecting mirror；The laser medium being arranged in cavity and exciter lamp；Wavelength selector, it is allowed to select the wavelength for laser pulse to be launched among multiple wavelength；And controller, control emitted energy and the transmitting of pulse of the exciter lamp launched timing, determine according to launch pulse with which wavelength in multiple wavelength of exciter lamp.Controller is continually transmitted by the spike train of multiple pulse shapings of the pulse including at least two wavelength.

Description

Laser equipment and control method thereof

Technical field

The present invention relates to laser equipment and control method thereof.

Background technology

Have been developed for using tunable (tunable) pulse laser for medical applications Photoacoustic tomography equipment (hereinafter, " PAT equipment ") (see S.Manohar et Al, Proc.of SPIE vol.6437 643702-1).PAT equipment is measurement apparatus, its to Part to be measured sends nanosecond laser pulses, receives by the ultrasound wave (light produced from this part Sound wave) signal that is converted to and analyze signal to obtain image.Expect that PAT equipment makes Obtain and can determine the most whether there is tumor or pass through base by the blood vessel that observation is gathered Spectrometry in the absorptance of the biological tissue of the wavelength according to the laser sent carries out living Internal functional analysis.

Think and use the adjustable of titanium sapphire crystal or alexandrite (alexandrite) crystal Humorous laser instrument is suitable as the light source of PAT equipment.Especially, due to as laser medium The long fluorescence lifetime of alexandrite crystal, therefore alexandrite laser can be direct by flash lamp Excite to be relatively easy to achieve high-energy output.

On the other hand, the emission spectra of flash lamp is wider, scope from ultraviolet to infrared so that with swash The concordance of the absorption spectra of light medium is poor.The heat energy of flash lamp makes the temperature of laser medium change Becoming, this causes the thermal lens (thermal being wherein refracted by the light beam of laser medium Lensing) effect.As with for observing the multi-wavelength Resonance scattering laser radar of air (lidar) report that the alexandrite laser of system is relevant is pointed out, it is known that alexandrite Laser instrument has significant thermal lensing effect.Therefore, in order to realize stable impulse ejection, need Reduce or stablize thermal lensing effect.

The Temperature Distribution of laser medium depends on heat energy and the laser medium provided by flash lamp The cooling effect of neighbouring circulation (circulating) water.Laser medium is dipped in following of constant temperature In ring water, and lamp energy is maintained constant simultaneously, in order to keep thermal lens power to be in stable shape State.Have been disclosed for wherein making the average lamp energy of every multiple pulse when changing lamp energy Constant to realize the method (United States Patent (USP) No.6193711) of stable impulse ejection.

Utilize PAT equipment, by using the laser of two or more wavelength, can basis Spectral differences between HbO2 Oxyhemoglobin and deoxyhemoglobin determines blood oxygen saturation.When based on Two wavelength use photoacoustic signal to obtain accurate intravital function information (such as oxygen saturation Degree) time, preferably the laser energy of two wavelength is exported and be maintained at same level.

Patent documentation 1: United States Patent (USP) No.6193711

Non-patent literature 1:S.Manohar et al, Proc.of SPIE vol.6437 643702-1

Summary of the invention

The vibration band of alexandrite laser is from 720nm to 800nm, and this coupling oxygenate is blood red Albumen or the absorption band of deoxyhemoglobin so that it is suitable to measure oxygen saturation.The opposing party Face, because gain intensity differs considerably for each wavelength, so the energy output of laser instrument Level differs considerably with 800nm vicinity near 750nm.Therefore, in order to realize with The stable impulse ejection at identical output level that wavelength is unrelated, needs changing wavelength Control the energy output of flash lamp simultaneously.

United States Patent (USP) No.6193711 discloses and utilizes Er:YAG laser pulse to carry out in vivo The effective method of irradiation.Er:YAG laser instrument sends the light at the wavelength of 2940nm, This light has higher reaction and produces little heat the water in biological tissue, and therefore fits For laser therapy.According to realizing stable pulse disclosed in United States Patent (USP) No.6193711 The method launched so that average for the flash lamp of pulse that includes in spike train (train) Energy output is constant, so that given the average heat energy of Er:YAG laser medium by flash lamp Constant.

But, it is different from use titanium sapphire or the laser of alexandrite with wide gain band Device, Er:YAG laser instrument sends light with fixed wave length.That is, United States Patent (USP) No.6193711 The method relating to controlling the laser instrument of fixed wave length.Shown in United States Patent (USP) No.6193711 Configuration is impermissible for easily varying wavelength, and be therefore consequently not used for being carried out by PAT Intravital functional diagnosis, this PAT uses the suction that biological tissue shows for different wave length Receive the difference of characteristic.

On the other hand, in the spectrometry using PAT, need a kind of permission from opening of irradiating Begun the driving method of the laser instrument carrying out the most accurate intravital measurement.

In view of problem as described above makes the present invention, and it is an object of the invention to pass through Tunable pulsed laser device independently to realize stable pulse output with wavelength.

The present invention provides a kind of laser equipment, comprising:

Cavity (cavity), is configured to include outgoing mirror and reflecting mirror；

The laser medium being arranged in cavity and exciter lamp (excitation lamp)；

Wavelength selector, is configured to allow to select to be swashed for launch among multiple wavelength The wavelength of light pulse；And

Controller, is configured to control the transmitting timing of exciter lamp, according to will be with in multiple wavelength Which wavelength launch pulse and the sending out of the emitted energy of exciter lamp that determines and pulse Penetrate, wherein

Controller is continually transmitted by multiple pulse shapings of the pulse including at least two wavelength Spike train.

The present invention also provides for a kind of control method for laser equipment, and this laser equipment includes: Cavity, including outgoing mirror and reflecting mirror；The laser medium being arranged in cavity and exciter lamp；Ripple Long selector, it is allowed to select the wavelength for laser pulse to be launched among multiple wavelength； And controller, the transmitting of control exciter lamp is regularly, basis will be with which ripple in multiple wavelength The emitted energy of the long exciter lamp launching pulse and determine and the transmitting of pulse,

Described method includes operating controller to be continually transmitted by including at least two wavelength The step of transmitting of spike train of multiple pulse shapings of pulse.

According to the present invention, tunable pulsed laser device can independently export stable arteries and veins with wavelength Punching.

From the description below with reference to the exemplary embodiment of accompanying drawing, the more feature of the present invention will It is apparent from.

Accompanying drawing explanation

Fig. 1 is the configuration figure of an embodiment of the laser equipment illustrating the present invention；

Fig. 2 A and Fig. 2 B is shown in an embodiment of the laser-driving method of the present invention Pulse pattern；

Fig. 3 is the configuration figure of an embodiment of the laser equipment illustrating the present invention；

Fig. 4 is the configuration figure of an embodiment of the laser equipment illustrating the present invention；

Fig. 5 A and Fig. 5 B illustrates the comparative example of pulse pattern；

Fig. 6 illustrates the comparative example of pulse pattern；

Fig. 7 is shown in the pulse diagram in an embodiment of the laser-driving method of the present invention Case；

Fig. 8 illustrates an embodiment of the laser-driving method of the present invention；

Fig. 9 is an embodiment of the laser equipment illustrating the present invention for light sound measurement Configuration figure；And

Figure 10 is the configuration figure of the embodiment illustrating PAT equipment.

Detailed description of the invention

Hereinafter, the preferred embodiments of the present invention will be described with reference to the drawings.Note, and unexpectedly The scope that this is invented by figure is limited to details given below, and described below is grouped The size of part, material, shape and positioned opposite etc. should be as required according to the application present invention's Configuration and the various condition of equipment and change.

The present invention is construed as tunable laser device and control method thereof.The present invention can To be applied to the light acoustic equipment including this tunable laser device as an element (PAT equipment).It is to say, it is to have the tunable laser device according to the present invention PAT equipment, this PAT equipment utilization laser irradiates subject to obtain and passing through optoacoustic effect Light absorbing part in subject produces and propagates through the photoacoustic waves of subject.By In the tunable laser device according to the present invention, the wavelength of the light being transmitted into subject can be with surely Fixed mode is varied so that the various tissues with different optical absorption characteristics (absorb simply The part of light) existence can be identified as characteristic information.The information obtained can be shown Show for diagnosis.

The sound wave (acoustic waves) mentioned in the present invention is typically ultrasound wave, bag Include referred to as sound wave (sound waves), ultrasound wave or the elastic wave of sound wave.By light sound effect The sound wave that should produce is referred to as " photoacoustic waves " or " photoinduced ultrasound wave ".

(configuration of equipment)

Fig. 1 illustrates an example of the configuration of the tunable laser being used in the present invention.Empty Chamber is formed by outgoing mirror 103 and reflecting mirror 104.Excitation cavity (chamber) 100, Q-switch 105 and wavelength selector 106 are disposed in cavity.Bar-shaped laser medium 101 With the flash lamp 102(exciter lamp for excitation laser medium 101) in excitation cavity 100 that This is disposed adjacent to.From the part of emitted energy of flash lamp 102 by laser medium 101 Absorb to produce the distribution of reversion, and reduced by Q-switch 105 at desired timing Loss in cavity is to launch the pulse of light.Laser medium 101 has high gain-bandwidth Laser crystal, and the wavelength of wavelength selector 106 permission selection output pulse.

The applicable example by the tunable pulsed laser device of Flashlamps exciting is titanium sapphire Laser instrument and alexandrite laser.These tunable pulsed laser utensils have coupling and oxygenated blood The oscillation wavelength band of the frequency band that Lactoferrin is corresponding with the absorption characteristic of deoxyhemoglobin so that it Can advantageously be used to detect blood oxygen saturation.Especially, alexandrite laser is permissible Easily by Flashlamps exciting and for each pulse output high-energy.In the example below, Laser medium will be described as alexandrite, but the invention is not restricted to alexandrite laser.

(thermal lensing effect)

There is flash lamp as in the laser instrument of excitaton source so that thermal lens power invariability so that It is requisite for realizing stable impulse ejection.Thermal lens described in detail below.When from sudden strain of a muscle When the light that light modulation is launched is absorbed by laser medium, heat is generated and changes the temperature of laser medium Degree.At this moment the most light absorbing part and the density of peripheral part and refractive index wait according to temperature Degree is distributed and changes.The temperature of laser medium depend on the heat energy from flash light emission and around The temperature of the water of laser medium circulation.Generally, the temperature of laser medium is in core and periphery Difference between part so that refractive index differs considerably between center and periphery, thus medium Show lens effect.This phenomenon wherein produced in the laser medium of thermal lens is referred to as heat Lens effect.

(maintaining the example of the control of the equilibrium temperature of laser medium)

An embodiment of the laser-driving method of the present invention is described below.Will be with reference to figure 2A substantially describe have the output of almost identical energy with the arteries and veins of the light of two emitting at different wavelengths Rush the example of pattern.In fig. 2, horizontal axis representing time (T), and the longitudinal axis represents flash lamp 102 Emitted energy (Elamp).

In the following description, utilize what the emitted energy of Elamp_a launched to swash with wavelength X a The pulse of light will be referred to as " pulse A ", and utilize the emitted energy of Elamp_b with wavelength X b The pulse of the laser launched will be referred to as " pulse B ".Utilize by pulse A and the group of pulse B The spike train being combined into repeatedly irradiates subject.Energy level Elamp_a and Elamp_b It is determined so that the energy of the pulse with emitting at different wavelengths exports the most identical. First wave length that wavelength X a and wavelength X b are considered in the definition of the present invention and the second ripple Long.

Dotted line in Fig. 2 A schematically shows the variations in temperature of laser medium (excellent).Because Temperature Distribution is there is in laser medium, so the temperature on the end central shaft of medium (Tlod) representative temperature of laser medium it is used as here.Laser medium 101 is dipped in be filled out Fill in the recirculated water of excitation cavity 100.Before flash lamp is switched on, the temperature of recirculated water is kept Constant.

When flash lamp 102 is switched on, the temperature of recirculated water and laser medium rises.Utilization sets It is set to so that wavelength X a exports identical corresponding emitted energy with the energy of the pulse of λ b Elamp_a and Elamp_b launches pulse A and pulse B.Because pulse A's and pulse B Spike train is repeated, so laser medium temperature Tlod gradually rises to steady statue.

Fig. 2 B illustrates the upper right side part surrounded by some chain lines of Fig. 2 A enlargedly.Arrow Point out the timing of Q-switch 105 impulse ejection.Because the different emitted energy utilizing lamp is launched Pulse A and pulse B, so laser medium temperature Tlod changes after each transmitting slightly Become.But, because average lamp energy is constant during whole spike train, so Tlod Change be the least.Correspondingly, the thermal lens power substantial constant of laser medium, and And pulse A and pulse B is stably launched.When laser medium temperature is in steady statue And when the most identical spike train is repeated, laser medium temperature is at pulse A and pulse B In the whole period substantial constant of each.Therefore, in the pulse with identical wavelength Between there is the difference of little light characteristic.

Although the variations in temperature of laser medium is greatly affected by the transmitting from flash lamp, but Be not only emissive porwer and also transmission interval is also important temperature governing factor.At pulse laser In the case of device, repetition rate is the highest, and the transmission interval of the flash lamp in pulse laser is the shortest, Make laser medium stably stand heat energy and therefore its temperature be greatly affected.More Body ground, repetition rate is the highest, the shadow of the thermal relaxation (thermal relaxation) of laser medium Ring the least so that laser medium temperature is stablized.

The preferred scope of following discussion repetition rate.From the viewpoint making laser medium temperature stabilization From the point of view of, 10Hz or more greatly, the repetition rate of preferably 20Hz or bigger should be used, But the thermal property of the specific heat of this size depending on laser medium and such as medium etc.Separately On the one hand, from the viewpoint of the laser equipment of design Flashlamps exciting, although this depends on executing It is added to the voltage of lamp, but in view of power supply capacity etc. generally uses the repetition of 100Hz or less Frequency.

Therefore, in the application as PAT equipment, for the laser equipment of the present invention, weight Complex frequency shall preferably be 10Hz to 50Hz, thus avoids the big load on equipment also And realize stable pulse output.

(for the compensation of thermal lensing effect)

Although laser can be made by the laser-driving method shown in Fig. 2 A and Fig. 2 B Medium temperature is to steady statue, but medium is not at thermal balance, this is because from flash lamp Light be launched in a pulsed fashion.Expression thermal lens can be caused more than the variations in temperature of specified quantitative The change of the thermal lens power of the degree of effect.

But, by being reduced as far as the variations in temperature of laser medium, this of thermal lens power Plant change and can be minimized to the least scope.If the change of thermal lens power is the least, Then can be by providing specific curvature to compensate thermal lensing effect for reflecting mirror.It is to say, it is logical Cross and the cavity determined by the curvature of outgoing mirror 103 and reflecting mirror 104 is configured to stable resonance Device guarantees stable impulse ejection.

More specifically, as it is shown in figure 1, reflecting mirror 104 is given curvature, such as to compensate Thermal lensing effect.In this case, light beam must perpendicularly enter into the center of reflecting mirror 104. Wavelength selector 106 should preferably have use and be formed by parallel flat board and putting down at it The type of birefringent filter rotated in face because light beam the most in such systems by Skew (misalign).Allow transmission expectation wavelength wavelengths filters can also advantageously by As wavelength selector 106.

If repetition rate is less than 10Hz, then laser medium temperature is more likely to due to thermal relaxation And change, but this depends on the difference of the emitted energy between pulse A and pulse B.If The difference of big laser medium temperature is there is, then shown in Fig. 3 between pulse A and pulse B Laser resonator design should be preferably used to heat penetration is adequately compensated for for each pulse Mirror effect.

(example of wavelength selector)

In figure 3, bar-shaped laser medium 101 and the flash of light for excitation laser medium 101 Lamp 102 is disposed adjacently to one another in excitation cavity 100.As shown in drawings, wavelength selector 106 Make light path fork that cavity is formed by outgoing mirror 103 and reflecting mirror 304, and another cavity Formed by outgoing mirror 103 and reflecting mirror 307.Along from outgoing mirror 103 to wavelength selector 106 Common light path in cavity, arrange excitation cavity 100 and Q-switch 105.By this of light path Individual fork, the light for pulse A is reflected by reflecting mirror 304, and for the light of pulse B by instead Penetrate mirror 307 to reflect.Each in two reflecting mirrors has and the thermal lens merit at corresponding wavelength The curvature that rate is consistent, in order to for the impulse compensation thermal lensing effect of corresponding wavelength.Wavelength selects Select device 106 and can have any configuration, as long as pulse is stably launched and can be from multiple Option selects expectation wavelength.

According to the method for the wavelength selecting wherein light path to be diverged known to a kind of, wavelength selector 106 can include fixed prism (to use based on dispersion of refractive index wavelength separated), with And for selecting the tripper of light beam to be launched.The method selecting wavelength according to another kind, Wavelength selector 106 can use parallel-plate to make light path fork and to select the light of light beam process Road.Dielectric film is arranged on the reflecting mirror for reflecting expectation wavelength.

Thermal lens power can also be by as illustrated in fig. 4 at wavelength selector 106 and excitation cavity Arrange between 100 the lens in telescope (telescope) 401 and regulation telescope 401 it Between distance and be compensated.In such a case it is possible to use the reflecting mirror with flat surfaces 404.By means of there is this mirror 404 of flat surfaces as reflecting mirror, it is not necessary to light beam is drawn Lead the center of reflecting mirror so that wavelength selector 106 can use and include light path for utilization The dispersion of refractive index prism etc. of change.

(maintaining another example of the control of the equilibrium temperature of laser medium)

From pulse pattern Fig. 2 A and Fig. 2 B shown in different pulse pattern is described below. Fig. 5 A, Fig. 5 B and Fig. 6 illustrate comparative example, and Fig. 7 illustrates the pulse diagram according to the present invention Case.Horizontal axis representing time (T), the emitted energy (Elamp) of longitudinal axis indication lamp, and dotted line Represent the change of laser medium temperature (Tlod) in corresponding accompanying drawing.

Fig. 5 A illustrates the comparative example 1 of pulse pattern.Along with the constant wavelength of λ a and profit Launch the pulse of light with the constant emission energy of Elamp_a, laser medium temperature Tlod is gradually Rise to heat-staple state.

Fig. 5 B illustrates the part surrounded by some chain lines in Fig. 5 A enlargedly.Arrow is pointed out The timing of Q-switch.Because flash lamp launches light in a pulsed fashion, so laser medium temperature is deposited In slight change.But, in steady statue, the temperature of laser medium is in the impulse ejection phase Between keep substantial constant so that thermal lens power is highly stable.Therefore, if wavelength Constant, utilize this pattern to realize stable impulse ejection.

Fig. 6 illustrates the comparative example 2 of pulse pattern.In this pattern, tens wavelength X a The pulse A with emitted energy Elamp_a and tens wavelength X b there is emission energy The pulse B of amount Elamp_b is alternately repeated.This accompanying drawing is shown in and is switched to from pulse A The change of laser medium temperature Tlod before and after pulse B.

As shown in Figure 6, laser medium temperature Tlod changes always.Temperature is even with identical Wavelength launch during pulse and change step by step.This big change along with laser medium temperature Changing, thermal lens power changes the most always so that thermal-lensing compensation is difficult, and is difficult to reality The most stable impulse ejection.

Fig. 7 illustrates an example of the pulse pattern according to the present invention.This pulse pattern is arteries and veins Rush A and the combination of pulse B, wherein pulse A and pulse B and pulse B and pulse A Spike train alternately repeated, such as AB, BA, AB.Average in each spike train Lamp energy is constant so that laser medium temperature keeps substantial constant.In this pattern, In addition to first pulse, the pulse (A or B) that double transmitting is identical.Therefore, make The half that number of times is repetition rate of wavelength, the instability thus associated must be changed with wavelength shift Factor is reduced.

Although Fig. 2 A, Fig. 2 B and Fig. 7 are shown with the example of the laser pulse of two wavelength, But pulse can be launched with three or more wavelength.It that case, make spike train In the quantity of pulse pattern that comprises equal to the quantity of the wavelength used, and for corresponding ripple Long setting emitted energy Elamp so that the average lamp energy of the pulse in spike train is substantially Constant.

If a spike train comprises pulse (pulse A, pulse B and the pulse of three wavelength C), then the order of the pulse in a spike train can be constant, or change every time, but Preferably they should be need not the sequential transmission of the complex control of wavelength selector.From heat penetration From the viewpoint of mirror compensates, the pulse in each spike train should always have identical order (such as, ABC) so that laser medium temperature will during the pulse of whole identical wavelength Identical.The quantity of the pulse pattern (that is, wavelength) in one spike train shall preferably be two Individual or more and no more than four, measure this is because PAT must quickly be realized.

<preheating (warm-up) processes>

Because PAT equipment is used for realizing based on the photoacoustic signal obtained in arranging from inceptive impulse So requisite, the functional analysis of biological tissue, is so that laser instrument exports from impulse ejection Start stable to realize higher diagnostic accuracy.Therefore, for stable laser instrument output, Before irradiation in vivo, the pre-heat treatment is required so that laser medium temperature arrive with Steady statue identical during actual intravital irradiation.

For this purpose, to make laser medium temperature in tripper can be arranged on cavity In the pre-heat treatment, steady statue is arrived in the case of not launching light.At shutter close and The temperature of the recirculated water near laser medium maintain constant in the case of, flash lamp is to live with reality The identical pattern of the pattern of the lamp emitted energy during internal irradiation is by repeated switch-on, in order to Laser medium temperature is made to arrive expectation steady statue.

After the pre-heat treatment, for the rapid transformation to actual treatment with irradiation, preferably Whether laser medium temperature was checked before the intravital irradiation determining to proceed to utilize laser It is in steady statue.Before irradiation the most in vivo, the energy output of laser instrument is directly surveyed Amount, and when energy output has become stable, the temperature of laser medium is determined being in surely Determine state.

Fig. 8 illustrates the control process of the Laser emission according to the present invention.

Step S801 be in the case of in cavity, shutter and external shutter are closed with irradiating The transmitting pattern launching pattern identical during the subject of such as live body etc makes flash lamp turn on Process.This is corresponding with the pre-heat treatment described above.May when starting from the transmitting of lamp There is the change of big thermal lens power, and the unstable light beam produced in cavity may damage Optical element in cavity.Therefore, the pre-heat treatment should preferably in cavity shutter close with Just start in the case of stopping Laser emission.External shutter should be also turned off avoiding tested The impact of body.

Step S802 be in the case of in cavity, shutter is opened with irradiate such as live body etc Subject time identical under conditions of change wavelength and while flash light emission light launch The process of pulse.The pulse train identical with during intravital irradiation is transmitted repeatedly. In this processes, it is arranged in the external shutter before live body and is turned off to cover relative to laser Subject.

Step S803 is by mean of the energy measurement meter (energy being externally arranged before shutter Meter) process of the energy output of whole pulse is measured.

Step S804 is that the energy checking the laser instrument determined by energy measurement meter has exported the most Through becoming stable to decide whether to start the place of the irradiation of subject at each wavelength Reason.Calculate the standard deviation of the energy output of the pulse of every predetermined quantity, and measure and repeated Until standard deviation becomes predetermined stationary value or lower.Wherein according to this laser controlling Method realizes in the application that PAT measures, and laser stabilization value can be measured required according to PAT Expectation quality be set.

Step S805 is to start with laser to irradiate the process of measured subject.Can be The energy output of laser instrument has become stable and has automatically begun to Laser emission afterwards.Alternately, Operator can be informed that energy output has been stablized, and beginning laser is sent out at expectation timing Penetrate.

PAT certainty of measurement can be increased by operations described above flow process.

In order to utilize PAT diagnostic techniques to measure the function of biological tissue, at identical measurement point On utilize different wave length laser irradiate subject, in order to from corresponding wavelength obtain optoacoustic letter Number, thus can extract the function information of biological tissue.Live body is made to protect the most as much as possible Hold motionless to maintain its position relative to PAT equipment so that from the light of each wavelength Acoustical signal can accurately be compared.Especially, in the case of hand-held PAT equipment, crucial Be that the movement making subject minimizes.Hand-held PAT equipment has in detector (probe) Receptor and light exit, and operator by this detector keep and be pressed on subject For measurement.Therefore there is subject relative to asking that the position of PAT equipment changes always Topic.

By means of such as by two wavelength near the 800nm repeated with the frequency of 20Hz Pulse composition pulse train, the measurement frequency of each wavelength is 10Hz, this for survey The function information of amount blood flow is the most frequently.Therefore, it is possible for accurately measuring, and reduces The impact that position during measurement is moved.Correspondingly, this is while changing wavelength continuously The method obtaining photoacoustic signal can be effectively improved the precision that photoacoustic spectrum is measured.

<embodiment 1>

The PAT equipment of the tunable pulsed laser device that wherein incorporate the present invention is described below One configuration and driving method.

(configuration of equipment)

Fig. 9 is the schematic diagram of the tunable pulsed laser device being incorporated in PAT equipment.This swashs Light device is that the repetition rate that can utilize 20Hz is launched with the wavelength of 800nm and 755nm The alexandrite laser of pulse.

Laser equipment is configured as follows.The flash of light exciting alexandrite is arranged in excitation cavity 900 Lamp 901 and alexandrite crystal 902.Alexandrite crystal is dipped in the recirculated water of 75 DEG C. Parallel-plate 906 is made up of synthetic quartz, and two surface is optically polished to have λ/20 Flatness and the depth of parallelism of 1 second of arc (arc second) or less.This plate has 30mm Thickness.

Outgoing mirror 903 is coated with the light of the wavelength for 800nm and 755nm and has 40% The dielectric film of absorbance.Reflecting mirror 904 is coated with the centre wavelength for 800nm Light has a reflectance coating of the dielectric substance of high reflectance, and reflecting mirror 908 be coated with for The light of the centre wavelength of 755nm has the reflectance coating of the dielectric substance of high reflectance.When parallel Plate 906 by when optical axis 905 retracts (retract) (position 906b), light beam along with light Consistent the first light path 909 of axle 905 is advanced and resonance.When parallel-plate 906 is inserted into light On axle 905 time (position 906a), light beam is moved in parallel, by branch road 907 and humorous Shake.

The Q-switch 911 being made up of Pockels unit is disposed in outgoing mirror 903 and excites On optical axis 905 between chamber 900.In cavity, shutter 912 is disposed in excitation cavity 900 peace Between andante.

Hand-held PAT equipment equipped with tunable pulsed laser device described above is used to survey Amount subject 914, this subject 914 is wherein to embed simulation to have the oxygen saturation of 80% The sample (anthropometric dummy (phantom)) of the simulation live body of the absorber of blood vessel.

(driving method)

The Laser Drive process of the present embodiment will be described step by step according to the flow chart of Fig. 8.

At step S801, start warm, wherein in external shutter 913 and cavity Shutter 912 is launched the pulse A with emitted energy 60J from lamp in the case of closing and is sent out with having Penetrate the pulse B of energy 48J.

After the preheating of ten minutes, at step S802, close also at external shutter 913 And in the case of shutter 912 is opened in cavity, start laser generation.At parallel-plate 906 from light In the case of axle 905 is pulled (position 906b), capacitor is charged to for making flash lamp Launch light.After charging, flash light emission light, and when energy exports after light emission During to peaking, after 150 μ sec, Q-switch is triggered.Then at outgoing mirror 903 with anti- Penetrate the light beam of resonance between mirror 904 and be launched as pulse A, its have 800nm wavelength, The pulse width of 50nsec, the energy output of 150mJ/ pulse, and the breadth of spectrum line of 8nm (full width at half maximum (FWHM) (full width at half maximum)).

After launching pulse A, parallel-plate 906 is inserted into alexandrite crystal 902 He On optical axis 905 between reflecting mirror 904 (position 906a).Capacitor start to be electrically charged so that It is moved parallel to parallel-plate 906 and from flash light emission light.Inserted at parallel-plate 906 After entering, flash light emission light.Q-switch is triggered after 150 μ sec after light emission. Light beam is advanced along branch road 907, and (this branch road 907 is formed when parallel-plate 906 is inserted into Light path), and resonance in the cavity formed by outgoing mirror 903 and reflecting mirror 908.This light Bundle be launched as pulse B, its have the wavelength of 755nm, the pulse width of 50ns, 150 The energy output of mJ/ pulse and the breadth of spectrum line (full width at half maximum (FWHM)) of 8nm.

Repeatedly launch pulse A and the spike train of pulse B.

At step S803, energy measurement meter (not shown) is utilized to measure each laser pulse Energy output, the energy of the light that this energy measurement measurement amount is reflected by external shutter.

At step S804,20 pulses every for each in pulse A and pulse B Calculate the standard deviation/average energy of the stability of instruction energy output.Energy measurement is repeated directly Becoming 2.5% or lower to value of calculation.When value of calculation has been changed to 2.5% or lower, The energy output of the notified laser instrument of operator has been stablized and thermal lens power stability The fact, this is because laser medium temperature is now arranged in steady statue.

At step S805, external shutter is opened, in order to launch stable to subject 914 Pulse train.

(PAT equipment)

Figure 10 is shown as the schematic diagram of the hand-held PAT equipment of an example of PAT equipment. The invention is not restricted to handset kind and other type can be applied to, such as, wherein patient The type procumbented or stand.

When external shutter 912 is opened, from tunable pulsed laser equipment 1001 injection Laser beam 1002 enters fibre bundle input 1003.Laser beam through fibre bundle 1004 and from The fibre bundle exit end 1005 of formation hand-held detector 1000 projects to subject and (such as simulates The anthropometric dummy of live body) on.

From the photoacoustic waves of subject generation by the receptor of the assembly as hand-held detector 1000 1006 pick up and are converted into photoacoustic signal, are sent to processor via holding wire 1007 1008 and be processed.Controller 1009 output is used for changing tunable pulsed laser equipment The control signal 1010 of the wavelength of 1001 and the output of flash lamp.

Processor 1008 according to based on photoemissive from tunable pulsed laser equipment 1001 Triggering signal 1011 process signal.Processor 1008 performs various process to photoacoustic signal, Such as analog digital conversion, image reconstruction and noise remove, and in being used for showing subject Characteristic distribution monitor 1012 output image information.

By this way, in using the measurement of PAT equipment of the application present invention, two are not The pulse A and pulse B of same wavelength (800nm and 755nm) are stably projected mould Intend the anthropometric dummy of live body, in order to obtain the optoacoustic letter of the blood vessel from the simulation in anthropometric dummy Number.Concentration C HbO of HbO2 Oxyhemoglobin and concentration C Hb of deoxyhemoglobin can be led to Cross the absorptance calculated under each wavelength according to the photoacoustic signal obtained to be determined, in order to derive Go out oxygen saturation { CHbO/ (CHbO+CHb) } × 100.Thus obtained by this method Oxygen saturation is 80%.

As it has been described above, the tunable pulsed laser device of the present invention can carry out the heat penetration with minimizing The stable impulse ejection of mirror effect, and make it possible to by caused by the movement of operator PAT measurement is accurately carried out in the case of impact that position is moved is less.

Although describing the present invention by reference to exemplary embodiment, but it is to be understood that this Bright it is not limited to disclosed exemplary embodiment.The scope of following claims will be given the widest Explain thus include all such amendments, the structure of equivalent and function.

Claims (16)

1. a laser equipment, including:

Cavity, is configured to include outgoing mirror and reflecting mirror；

The laser medium being arranged in cavity and exciter lamp；

Wavelength selector, is configured to allow to select laser arteries and veins to be launched among multiple wavelength The wavelength of punching；And

Controller, is configured to control the transmitting timing of exciter lamp, according to will be with in multiple wavelength Which wavelength launch pulse and the sending out of the emitted energy of exciter lamp that determines and pulse Penetrate so that laser equipment is continually transmitted by multiple pulses of the pulse including at least two wavelength The spike train formed.

Laser equipment the most according to claim 1, wherein

Wavelength selector in pulse choice first wave length and second wave length, and

Controller is configured to control the transmitting timing of exciter lamp, basis will be with in multiple wavelength The emitted energy of exciter lamp and the transmitting of pulse which wavelength is launched pulse and determined make Obtain laser equipment repeatedly to launch by two kinds of pulse shapings and wherein in the pulse of first wave length The spike train of the pulse followed by launching second wave length.

Laser equipment the most according to claim 1, wherein

Wavelength selector in pulse choice first wave length and second wave length, and

Controller is configured to control the transmitting timing of exciter lamp, basis will be with in multiple wavelength The emitted energy of exciter lamp and the transmitting of pulse which wavelength is launched pulse and determined make Obtain laser equipment alternately to launch by two kinds of pulse shapings and wherein in the pulse of first wave length The pulse followed by launching second wave length spike train and by two kinds of pulse shapings and its In at the spike train of the pulse followed by launching first wave length of pulse of second wave length.

Laser equipment the most according to claim 1, wherein

Controller is configured to control the transmitting timing of exciter lamp, basis will be with in multiple wavelength The emitted energy of exciter lamp and the transmitting of pulse which wavelength is launched pulse and determined make Obtain laser equipment and repeatedly launch identical spike train.

Laser equipment the most according to claim 1, also include being arranged in cavity is fast Door, wherein

Controller perform wherein at shutter close so that making in the case of the most exomonental to excite Lamp conducting is so that the pre-heat treatment that makes laser medium be equilibrium temperature state.

Laser equipment the most according to claim 1, also includes energy measurement meter, described Energy measurement meter is configured to measure the energy output of pulse, wherein

Controller has been stablized based on energy output and has been determined whether laser medium is in surely Fixed temperature state.

Laser equipment the most according to claim 1, wherein

Reflecting mirror has the curvature of the thermal lensing effect compensated in laser medium.

Laser equipment the most according to claim 1, also include being arranged in laser medium and Telescope between wavelength selector, wherein

Telescope compensates the thermal lens in laser medium by the distance of regulation lens to lens Effect.

9. a light acoustic equipment, including:

According to the laser equipment that in claim 1 to 8, any one is described；

Receptor, is configured to receive from having absorbed the laser launched from described laser equipment The sound wave that the subject of pulse produces；And

Processor, is configured to obtain the information of the inside of subject based on sound wave.

10. a light acoustic equipment, including:

According to the laser equipment described in Claims 2 or 3；

Receptor, is configured to receive from having absorbed the laser launched from described laser equipment The sound wave that the subject of pulse produces；And

Processor, is configured to obtain the information of the inside of subject based on sound wave, wherein

Two wavelength correspond respectively to absorption characteristic and the deoxyhemoglobin of HbO2 Oxyhemoglobin Absorption characteristic.

11. 1 kinds of control methods for laser equipment, this laser equipment includes: cavity, bag Include outgoing mirror and reflecting mirror；The laser medium being arranged in cavity and exciter lamp；Wavelength selector, Allow to select the wavelength of laser pulse to be launched among multiple wavelength；And controller, control Exciter lamp processed launch timing, according to launching pulse with which wavelength in multiple wavelength The emitted energy of the exciter lamp determined and the transmitting of pulse,

Described method includes that operating controller makes laser equipment be continually transmitted by including at least The step of transmitting of the spike train of multiple pulse shapings of the pulse of two wavelength.

12. control methods for laser equipment according to claim 11, also include Operative wavelength selector is so that for a 's in pulse choice first wave length and second wave length Select step, wherein

Controller is configured to control the transmitting timing of exciter lamp, basis will be with in multiple wavelength The emitted energy of exciter lamp and the transmitting of pulse which wavelength is launched pulse and determined make Obtain laser equipment repeatedly to launch by two kinds of pulse shapings and wherein in the pulse of first wave length The spike train of the pulse followed by launching second wave length.

13. control methods for laser equipment according to claim 11, also include Operative wavelength selector is so that for a 's in pulse choice first wave length and second wave length Select step, wherein

Controller is configured to control the transmitting timing of exciter lamp, basis will be with in multiple wavelength The emitted energy of exciter lamp and the transmitting of pulse which wavelength is launched pulse and determined make Obtain laser equipment alternately to launch by two kinds of pulse shapings and wherein in the pulse of first wave length The pulse followed by launching second wave length spike train and by two kinds of pulse shapings and its In at the spike train of the pulse followed by launching first wave length of pulse of second wave length.

14. control methods for laser equipment according to claim 11, wherein control Device processed is configured to control the transmitting timing of exciter lamp, basis will be with which ripple in multiple wavelength The long emitted energy of exciter lamp and the transmitting of pulse launching pulse and determine makes laser Equipment repeatedly launches identical spike train.

15. control methods for laser equipment according to claim 11, wherein swash Light device also includes the shutter being arranged in cavity, and

Described method also includes, before described step of transmitting, operation controller is to perform it In at shutter close so that make in the case of the most exomonental exciter lamp turn on so that making to swash Light medium is the preheating step of the pre-heat treatment of equilibrium temperature state.

16. according to any one in claim 11 to 15 described for laser equipment Control method, wherein laser equipment also includes the energy measurement of the energy output for measuring pulse Meter, and

Described method also includes, before described step of transmitting, operation controller is so that based on energy Amount output has stablized to determine the step whether laser medium is in equilibrium temperature state.