Novel visible band multi-wavelength laser

Abstract

The novel visible wave band multi-wavelength laser comprises a machine body, a pumping source, a total reflection lens, a neodymium-doped yttrium vanadate crystal, a Q switch, a middle lens, a first BBO crystal, a second BBO crystal and an output lens are sequentially arranged in the machine body, and the total reflection lens and the output lens form an oscillation cavity. The axial center lines of the pumping source, the total reflection lens, the neodymium-doped yttrium vanadate crystal, the Q switch, the middle lens, the first BBO crystal, the second BBO crystal and the output lens are overlapped, a horizontal rotation adjusting table is arranged at the lower end of the first BBO crystal, a fixed platform is arranged at the lower end of the second BBO crystal, and the first BBO crystal is rotated through fine tuning to adjust the axial center lines of the neodymium-doped yttrium vanadate crystal, the Q switch and the middle lens. And the light passing direction of the first BBO crystal is consistent with the phase matching angle required by the output of the corresponding wavelength, so that the frequency mixing of the corresponding fundamental frequency light or each order of Stokes light in the laser resonant cavity is selectively realized, and the visible band laser with different wavelengths is correspondingly output. The technical scheme is reasonable in structural design, high in laser efficiency, stable in output and good in practicability.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of photoelectric device, concretely relates to a novel visible wave band multi-wavelength laser. BACKGROUND

[0002] Visible wave band multi-wavelength laser has important application in the field such as laser display, biomedical, radar remote sensing. The typical application is like the treatment of fundus disease. Fundus disease is the most common disease in the field of ophthalmology, aiming at the different color light absorption characteristics of different pathological tissues, selecting different wavelength laser for treatment can improve the treatment effect, reduce the damage to the tissue and expand the diagnosis and treatment range of ophthalmic clinic. Compared with single wavelength laser, multi-wavelength laser treatment can overcome the obstacle of eye refractive medium turbidity in the treatment of fundus disease, and become the development direction of ophthalmic clinical laser treatment.

[0003] Multi-wavelength krypton laser treatment machine enters the ophthalmology clinic earlier, and is a multi-wavelength laser treatment device for eye fundus diseases that is widely used at present. However, krypton laser belongs to gas laser, and has the disadvantages of large volume, low efficiency, poor stability and reliability and the like. In recent years, with the development of semiconductor-pumped solid-state laser technology, the multi-wavelength selectable laser based on intracavity frequency doubling and sum frequency technology of all-solid-state Raman cavity has become the most potential light source for eye fundus treatment due to the advantages of all-solid-state, simple structure, convenient wavelength switching and the like. Through retrieval, the utility model patent CN201910306311.3 discloses a five-wavelength laser source for laser eye fundus photocoagulation treatment, which comprises a machine body, and a pump source, a full reflection mirror, a Nd:YAlO3 crystal, a Q switch, a YVO4 crystal, a BBO crystal, an output mirror, a coupling lens system and an optical fiber are sequentially arranged in the machine body from left to right. The coupling lens system comprises a coupling lens, and the full reflection mirror and the output mirror constitute an oscillation cavity. The axial center lines of the pump source, the full reflection mirror, the Nd:YAlO3 crystal, the Q switch, the YVO4 crystal, the BBO crystal and the output mirror coincide. By rotating the BBO crystal, the light transmission direction of the BBO crystal is consistent with the required phase matching angle of corresponding wavelength output, so that the mixing of corresponding fundamental light or each order Stokes light in the laser resonant cavity is realized, and visible band laser of different wavelengths is output. The technical scheme overcomes the shortcomings of the previous krypton multi-wavelength laser treatment device to a certain extent, and expands the indication range of eye fundus treatment. However, the use of the broadband high-reflection mirror system of the cavity mirror to meet the requirements of cascade Raman is prone to cause the gain competition of higher order Stokes light when frequency doubling and sum frequency, thereby affecting the power and stability of the required wavelength laser. For example, when the first-order Stokes light is frequency doubled, the resonant cavity is also highly reflective to the second-order Stokes light, and even nearly totally reflective, so that more first-order Stokes light is converted into second-order Stokes light by passing through the Raman crystal, that is, the second-order Stokes light participates in the consumption of the first-order Stokes light, and the frequency doubling efficiency, output power and laser stability of the first-order Stokes light are affected. In addition, the nonlinear optical frequency conversion crystal used in the above patent is the BBO crystal with critical phase matching, and the walk-off angle reaches more than 50 mrad. The birefringence walk-off effect will cause the separation of the energy flow directions of the two different polarized lights participating in the frequency conversion, and affect the beam quality and frequency doubling conversion efficiency of the laser output. Content of the utility model

[0004] In view of the deficiencies in the prior art, the purpose of the utility model is to provide a novel visible band multi-wavelength laser with reasonable structure design, high laser efficiency, stable output and good practicality.

[0005] To achieve the above object, the utility model provides the following technical scheme: A novel visible wave band multi -wavelength laser, including the organism, the pump source, the full reflection mirror piece, the doped neodymium yttrium vanadate crystal, Q switch, intermediate mirror piece, first BBO crystal, second BBO crystal and output mirror piece are sequentially arranged in the organism, the full reflection mirror piece and output mirror piece constitute the oscillation cavity, the axial center line of pump source, full reflection mirror piece, doped neodymium yttrium vanadate crystal, Q switch, intermediate mirror piece, first BBO crystal, second BBO crystal and output mirror piece coincides and is placed, the horizontal rotation adjustment platform is arranged to the first BBO crystal lower extreme, the fixed platform is arranged to the second BBO crystal lower extreme, through the fine adjustment rotation first BBO crystal, with the corresponding wavelength output required phase matching angle consistent, thereby selection realizes the mixing of corresponding fundamental frequency light or each order stokes light in laser resonant cavity, and the visible wave band laser of different wavelength is output.

[0006] The utility model further sets up: the first BBO crystal and second BBO crystal are two crystals that size and optical parameter are all same, and are cut according to the phase matching angle of 1313nm frequency multiplication, and the angle of light direction and crystal optical axis is 20.4 °.

[0007] The utility model further sets up: the rotatable angle of horizontal rotation adjustment platform is greater than 2.5 degrees.

[0008] The utility model further sets up: the optical axis of first BBO crystal and second BBO crystal is placed in mirror image, and plays the role of birefringence walk-off compensation in nonlinear frequency conversion.

[0009] The utility model further sets up: the oscillation cavity realizes that fundamental frequency laser, first order stokes light and second order stokes light oscillate in the cavity simultaneously.

[0010] The utility model further sets up: the high reflection film of from 1.06 micrometers to 1.32 micrometers wave band laser is coated on the full reflection mirror piece;The antireflection film of from 1.06 micrometers to 1.32 micrometers wave band laser and the high reflection film of from 0.56 micrometers to 0.62 micrometers wave band laser are coated on intermediate mirror piece;The high reflection film of from 1.06 micrometers to 1.32 micrometers wave band laser and the high transmission film of from 0.53 micrometers to 0.66 micrometers wave band laser are coated on output mirror piece.

[0011] The utility model further sets up: the pump source is the semiconductor laser of output wavelength 808 nanometers or 880 nanometers.

[0012] The utility model further sets up: Q switch is the acoustooptic Q switch of 1.06 micrometers to 1.32 micrometers wave band high transmissivity.

[0013] The utility model discloses the beneficial effect is: compared with prior art, the utility model discloses reasonable structure design, the whole organism uses two pieces of mirror image setting's BBO crystal, through the fine adjustment rotation first BBO crystal, with the light transmission direction of first BBO crystal and the phase matching angle required for corresponding wavelength output are identical, thereby selection realizes the mixing of corresponding fundamental frequency light or each order stokes light in laser resonant cavity, and the visible waveband laser of different wavelength is outputted. The second BBO crystal plays the regulation effect to stokes light, when the frequency multiplication and the sum frequency of not needing two order stokes, plays the loss effect of increasing two order stokes light, reaches the efficiency of reducing the conversion of first order to two order stokes light, thereby plays the loss effect of reducing first order stokes light, in addition, can also compensate the birefringence walk-off effect of first BBO crystal, is favorable for the beam quality effect of mixing output laser. The two regulation effects of second BBO crystal can all play the conversion efficiency effect of promoting first order stokes light frequency multiplication. Finally realize the visible waveband laser of high efficiency, high beam quality.

[0014] The utility model will be further described below in conjunction with the drawings and specific embodiments. DRAWINGS

[0015] Fig. 1 It is the optical path principle drawing of the utility model embodiment;

[0016] Fig. 2 It is the principle drawing of the visible waveband five wavelength generation of the utility model embodiment. CONCRETE IMPLEMENTING METHOD

[0017] In the description of the embodiment, it is necessary to explain that, if the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inner", "outer", "front", "back" and the like appear, the orientation or position relation that the indicated is based on the orientation or position relation shown in the drawing, just is for the convenience of describing the utility model and simplifying the description, and is not indicated or implied that the indicated device or element must have a particular orientation, construct and operate with a particular orientation, therefore, can not be understood as the limitation to the utility model. In addition, if the terms "first", "second", "third" appear, just are for the description purpose, and can not be understood as indicating or implying relative importance.

[0018] Reference Figs. 1-2The utility model discloses a novel visible waveband multi-wavelength laser, including the organism, the pump source 1, the total reflection mirror piece 2, the doped neodymium yttrium vanadate crystal 3, Q switch 4, the intermediate mirror piece 5, the first BBO crystal 6, the second BBO crystal 8 and the output mirror piece 10 are sequentially arranged in the organism, the total reflection mirror piece 2 and the output mirror piece 10 constitute the oscillation cavity, the axial center line of the pump source 1, the total reflection mirror piece 2, the doped neodymium yttrium vanadate crystal 3, Q switch 4, the intermediate mirror piece 5, the first BBO crystal 6, the second BBO crystal 8 and the output mirror piece 10 coincide and place, the first BBO crystal 6 lower end is provided with horizontal rotation adjustment platform 7, the second BBO crystal 8 lower end is provided with fixed platform 9, through the fine adjustment rotation first BBO crystal 6, make the light transmission direction of first BBO crystal 6 and the corresponding wavelength output required phase matching angle consistent, thereby selection realizes the mixing of corresponding fundamental frequency light or each order stokes light in the laser resonant cavity, and the visible waveband laser of different wavelength is outputted.

[0019] The oscillation cavity realizes that the fundamental frequency laser, the first order stokes light and the second order stokes light oscillate simultaneously in the cavity.

[0020] In order to make the utility model structure design more reasonable, as preferred, the first BBO crystal 6 and the second BBO crystal 8 of the embodiment are two crystals that are same in size and optical parameter, and are cut according to the phase matching angle of 1313nm frequency doubling and the included angle of light transmission direction and crystal optical axis is 20.4°. The rotatable angle of the horizontal rotation adjustment platform 7 is greater than 2.5 degrees.

[0021] The optical axis of the first BBO crystal 6 and the second BBO crystal 8 is placed in mirror image, and plays the birefringent walk-off compensation role in nonlinear frequency conversion.

[0022] The total reflection mirror piece 2 is coated with high reflection film of 1.06 micrometer to 1.32 micrometer waveband laser, the intermediate mirror piece 5 is coated with antireflection film of 1.06 micrometer to 1.32 micrometer waveband laser and high reflection film of 0.56 micrometer to 0.62 micrometer waveband laser, and the output mirror piece 10 is coated with high reflection film of 1.06 micrometer to 1.32 micrometer waveband laser and high transmission film of 0.53 micrometer to 0.66 micrometer waveband laser.

[0023] The pump source 1 is a semiconductor laser with output wavelength of 808 nanometers or 880 nanometers.

[0024] The Q switch 4 is an acousto-optic Q switch with high transmittance of 1.06 micrometer to 1.32 micrometer waveband.

[0025] In practical application, under the action of the pump source, the neodymium-doped yttrium vanadate crystal forms the fundamental light of 1.06-micron band in the cavity composed of the full reflection mirror and the output mirror, and continuously oscillates and strengthens; when the intensity of the fundamental light reaches the Raman conversion threshold of the neodymium-doped yttrium vanadate crystal, part of the fundamental light of 1.06-micron band generates the first-order Stokes light of 1.18-micron band through a Raman frequency shift, and simultaneously oscillates and strengthens in the cavity composed of the full reflection mirror and the output mirror; when the intensity of the first-order Stokes light of 1.18-micron band reaches the Raman conversion threshold of the neodymium-doped yttrium vanadate crystal, part of the first-order Stokes light of 1.18-micron band generates the second-order Stokes light of 1.31-micron band through a Raman frequency shift, and simultaneously oscillates and strengthens in the cavity composed of the full reflection mirror and the output mirror. Therefore, the fundamental light of 1.06-micron band, the first-order Stokes light of 1.18-micron band and the second-order Stokes light of 1.31-micron band can exist in the cavity composed of the full reflection mirror and the output mirror at the same time. The Q-switch is mainly used to realize the Q-switched pulse laser operation and improve the peak power of the fundamental light and the first-order and second-order Stokes light in the cavity.

[0026] Table 1: the matching angle and walk-off angle of BBO crystal corresponding to the mixing of each wavelength

[0027]

[0028] Table 1 shows the matching angle of BBO crystal corresponding to the mixing of each wavelength obtained by theoretical calculation. The matching angle is the value corresponding to the angle between the light transmission direction and the optical axis of the crystal when the frequency doubling or sum frequency of the "wavelength combination" is realized. The laser of each wavelength in the oscillation cavity is adjusted by rotating the horizontal rotation adjustment table to fine-tune the angle of the first BBO crystal, so that the angle between the light transmission direction and the optical axis of the crystal corresponds to the value of "BBO matching angle" in Table 1, thereby realizing the sum frequency or frequency doubling of different wavelengths, and realizing the conversion of visible band laser to the wavelength corresponding to "output wavelength" in Table 1. The intermediate mirror is used to reflect the visible band laser transmitted in the opposite direction, and finally the visible band laser is output by the output mirror. The first BBO crystal is placed in mirror image with the second BBO crystal, which can play a role in pulling back the walk-off beam to improve the frequency conversion efficiency and improve the quality of the output laser beam. In addition, the second BBO crystal is cut according to the phase matching angle of the second-order Stokes light frequency doubling, which can convert the frequency doubling of the second-order Stokes light in the cavity. When the second-order Stokes light participates in the frequency doubling, it plays a role in increasing the frequency doubling efficiency. When the second-order Stokes light does not participate, it also has an important role in increasing the loss of the second-order Stokes light, thereby reducing the conversion efficiency from the first-order to the second-order Stokes light The conversion efficiency of the second-order nonlinear optical process is improved, and the conversion efficiency of the first-order Stokes light frequency doubling is improved.

[0029] The utility model discloses reasonable structure setting, two pieces of mirror image setting's BBO crystal in whole organism is used, through the fine adjustment rotation first BBO crystal, make first BBO crystal's light transmission direction and corresponding wavelength output required phase matching angle consistent, thereby selection realizes the mixing of corresponding fundamental frequency light or each order stokes light in laser resonant cavity, and the output different wavelength visible waveband laser is corresponded. Wherein the second BBO crystal plays the regulation and control effect to stokes light, when the frequency multiplication and the sum frequency of not needing the second order stokes participation, play the loss effect of increasing to the second order stokes light, reach the efficiency of reducing the conversion of the first order to the second order stokes light, thereby play the loss effect of reducing the first order stokes light, in addition, can also compensate the birefringence walk-off effect of first BBO crystal, is favorable to the beam quality effect of mixing output laser. The two regulation and control effects of second BBO crystal can all play the conversion efficiency effect of promoting the frequency multiplication of the first order stokes light. Finally realize the visible waveband laser of high efficiency, high beam quality.

[0030] The above embodiments are only used for further illustrating the utility model, and cannot be understood as limiting the protection scope of the utility model. The skilled in the art can make some non-essential improvements and adjustments to the utility model according to the content of the above utility model, and all of these fall within the protection scope of the utility model.

Claims

1. A novel visible band multiwavelength laser comprising a body, characterized in that: The machine body is sequentially provided with a pump source (1), a total reflection mirror (2), a neodymium-doped yttrium vanadate crystal (3), a Q switch (4), an intermediate mirror (5), a first BBO crystal (6), a second BBO crystal (8) and an output mirror (10), the total reflection mirror (2) and the output mirror (10) form an oscillation cavity, the pump source (1), the total reflection mirror (2), the neodymium-doped yttrium vanadate crystal (3), the Q switch (4), the intermediate mirror (5), the first BBO crystal (6), the second BBO crystal (8) and the output mirror (10) are coaxially arranged, the first BBO crystal (6) is provided with a horizontal rotation adjusting platform (7) at the lower end, the second BBO crystal (8) is provided with a fixed platform (9) at the lower end, the first BBO crystal (6) is finely rotated so that the light transmission direction of the first BBO crystal (6) is consistent with the required phase matching angle of corresponding wavelength output, thereby realizing the mixing of corresponding fundamental light or each order of Stokes light in the laser resonant cavity, and outputting visible band lasers of different wavelengths.

2. A novel visible band multiwavelength laser as claimed in claim 1, wherein: The first BBO crystal (6) and the second BBO crystal (8) are two crystals with the same size and optical parameters, and are cut at an angle of 20.4° between the light transmission direction and the optical axis of the crystal according to the phase matching angle of 1313 nm frequency multiplication.

3. A novel visible band multiwavelength laser as claimed in claim 2, wherein: The rotatable angle of the horizontal rotation adjusting platform (7) is greater than 2.5 degrees.

4. A novel visible band multiwavelength laser as claimed in claim 3, wherein: The optical axes of the first BBO crystal (6) and the second BBO crystal (8) are mirror placed, and play a birefringent walk-off compensation role in nonlinear frequency conversion.

5. A novel visible band multiwavelength laser as claimed in claim 1 or 4, wherein: The oscillation cavity realizes the simultaneous oscillation of fundamental laser, first-order Stokes light and second-order Stokes light in the cavity.

6. A novel visible band multiwavelength laser as claimed in claim 5, wherein: The total reflection mirror (2) is coated with a high reflection film of laser in the 1.06-1.32 micron band; the intermediate mirror (5) is coated with an antireflection film of laser in the 1.06-1.32 micron band and a high reflection film of laser in the 0.56-0.62 micron band; and the output mirror (10) is coated with a high reflection film of laser in the 1.06-1.32 micron band and a high transmission film of laser in the 0.53-0.66 micron band.

7. A novel visible band multiwavelength laser as claimed in claim 6, wherein: The pump source (1) is a semiconductor laser with an output wavelength of 808 nm or 880 nm.

8. A novel visible band multiwavelength laser as claimed in claim 7, wherein: The Q switch (4) is an acousto-optic Q switch with high transmittance in the 1.06-1.32 micron band.

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