LASER DRIVING DEVICE AND METHOD FOR ENABLING UNIFORM LIGHT FIELD

Abstract

A laser driving device and a method for enabling a uniform light field, wherein the laser driving device is a high-power laser driving device that enables a uniform light field on the basis of a narrow-band low-spatial-coherence light and is provided for laser fusion. The narrow-band low-spatial-coherence light is configured as a seed of the laser driving device, an amplification and transmission unit amplifies the seed, a frequency conversion unit converts a frequency of the laser, and a focusing component is configured for laser focusing and uniform illumination.

Claims

1. A laser driving device, comprising: a laser seed (1), an amplification and transmission unit (2), a frequency conversion unit (3), and a focusing unit (4), wherein the laser seed (1) is a narrow-band low-spatial-coherence light source and configured for generating a narrow-band low-spatial-coherence laser, the amplification and transmission unit (2) is configured for amplifying and transmitting the laser, the frequency conversion unit (3) is configured for converting frequencies of the laser, and the focusing unit (4) is configured for laser focusing; the laser seed (1) generates a narrow-band low-spatial-coherence light, the narrow-band low-spatial-coherence light is amplified by the amplification and transmission unit (2) and is subjected to frequency conversion performed by the frequency conversion unit (3), and then the light with a converted frequency is focused by the focusing unit (4).

2. The laser driving device according to claim 1, wherein the laser seed (1) is a low-spatial-coherence light source with a bandwidth not more than 10 Å.

3. The laser driving device according to claim 1, wherein a modulus of a complex spatial coherence of a light field of the laser from the laser seed (1) is less than 1.

4. The laser driving device according to claim 1, wherein the amplification and transmission unit (2) comprises one or more amplification gain media.

5. The laser driving device according to claim 4, wherein the amplification gain medium is a rod or a plate.

6. The laser driving device according to claim 4, wherein the amplification and transmission unit (2) comprises spatial transmission means for controlling a divergence angle of a light beam to regulate the transmission of the laser beam.

7. The laser driving device according to claim 1, wherein the frequency conversion performed by the frequency conversion unit (3) can be frequency doubling, frequency tripling, or frequency quadrupling.

8. The laser driving device according to claim 1, wherein the focusing unit (4) comprises an optical element for focusing.

9. The laser driving device according to claim 1, wherein the focusing unit (4) further comprises arrayed lenses or arrayed orthogonal cylindrical lenses.

10. The laser driving device according to claim 1, wherein the focusing unit (4) further comprises an optical element for adjusting phases.

11. The laser driving device according to claim 1, further comprising a beam shaping component (6) configured for controlling intensities and phases of a light beam.

12. The laser driving device according to claim 11, wherein the beam shaping element (6) is one or more of a serrated aperture, a birefringent lens group in conjunction with a neutral density filter, an amplitude-type (or phase-type) binary optical panel, a binary transmittance liquid crystal cell, an amplitude-type electrical addressing modulator, an amplitude-type optical addressing modulator, a phase-type electrical addressing spatial light modulator, and an adaptive optical component.

13. The laser driving device according to claim 1, further comprising a measurement unit (7) for measuring various types of signals in the laser driving device.

14. The laser driving device according to claim 1, further comprising a collimation component (8) for collimating each light beam in the laser driving device.

15. The laser driving device according to claim 1, further comprising a control component (9) for controlling various types of signals in the laser driving device.

16. A method for enabling a uniform light field according to claim 1, comprising adopting a narrow-band low-spatial-coherence light source as the laser seed (1), amplifying light by the amplification and transmission unit (2) to obtain an amplified light, subjecting the amplified light to frequency conversion by the frequency conversion unit (3), and converting the light with a converted frequency and focusing the light by the focusing unit (4) to enable a light field with uniform near and far fields.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] FIG. 1 shows a simplified structure of the present invention.

[0039] FIG. 2A shows a structure of a spatial filter in an amplification and transmission unit (2) of a laser driving device according to the present invention; FIG. 2B shows a structure of the spatial filter in the amplification and transmission unit (2) of a convention laser driving.

[0040] FIG. 3A shows a frequency conversion unit (3) of the laser driving device according to the present invention (frequency tripling); FIG. 3B shows the frequency conversion unit (3) of the conventional laser driving device (frequency tripling).

[0041] FIG. 4 shows a focusing unit (4) of the laser driving device according to the present invention.

[0042] FIGS. 5A and 5B show a near-field (FIG. 5A) and a far-field (FIG. 5B) of a light field after amplification and transmission and frequency conversion according to the present invention.

[0043] FIG. 6 shows the frequency conversion unit (3) of the laser driving device according to the present invention (frequency quadrupling).

[0044] FIG. 7 shows the focusing unit (4) of the laser driving device according to the present invention.

[0045] FIG. 8 shows the focusing unit (4) of the laser driving device according to the present invention.

[0046] FIG. 9 shows the focusing unit (4) of the laser driving device according to the present invention.

[0047] FIG. 10 shows a structure of the laser driving device, including a collimation component (8), a measurement unit (7), and a control component (9).

[0048] FIG. 11 shows a structure of the laser driving device including a beam shaping component.

[0049] FIG. 12 shows a structure of the laser driving device including the beam shaping component.

[0050] FIG. 13 shows a spatial transmission means in the amplification and transmission unit (2) of the laser driving device according to the present invention.

[0051] Reference numbers used in the figures refer to the following structures:

[0052] 1—laser seed; 2—amplification and transmission unit; 3—frequency conversion unit; 4—focusing unit; 5—target; 6—beam shaping component; 7—measurement unit; 8—collimation component; 9—control component;

[0053] 202—spatial filter; 201—pre-amplifier stage; 203—post-amplification stage; 2021—first beam expanding lens; 2022—spatial filtering aperture; 2023—second beam expanding lens, 204—simplified spatial filter; 205—¼ wave plate; 206—rod-shaped laser head of amplification gain medium; 207—first polarizing beam-splitter prism; 208—intracavity spatial filter; 209—first reflective lens; 210—second polarizing beam-splitter prism; 211—spatial transmission filter; 212—Faraday rotator; 213—second reflective lens; 214—beam expander; 215—first sheet-shaped laser head of amplification gain medium; 216—first spatial filter; 217—second sheet-shaped laser head of amplification gain medium; 218—polarizing emission lens; 219—first total reflection lens; 220—second total reflection lens; 221—second spatial filter; 222—spatial transmission device; 2221—first lens; 2222—second lens;

[0054] 30—fundamental-frequency random-phase mask; 31—vacuum window; 32—frequency doubling crystal; 33—frequency tripling crystal; 34—frequency-doubling random-phase mask; 35—frequency quadrupling crystal;

[0055] 41—aspheric lens; 42—wedge-shaped focusing lens; 43—deformable reflective lens; 44—arrayed lenses; 45—beam deflection lens group; 46—reflective focusing lens;

[0056] 61—deformable reflective lens; 62—serrated aperture.

DETAILED DESCRIPTION OF THE INVENTION

[0057] The present invention is further described in connection with the following examples with reference to the drawings. These examples do not serve to limit the scope of the present invention and modification may be made without departing from the scope of the invention.

Example 1

[0058] The Example provides a laser driving device as shown in FIG. 1 comprising a laser seed (1), an amplification and transmission unit (2), a frequency conversion unit (3), a focusing unit (4), and a target (5). The laser seed (1) is narrow-band low-spatial-coherence light with a bandwidth of 5 Å; the coherent light is amplified and transmitted through the amplification and transmission unit (2) and subjected to frequency conversion performed by the frequency conversion unit (3), and the light with a converted frequency is focused by the focusing unit (4) to irradiate the target (5) finally.

[0059] The amplification and transmission unit (2) in the example, as shown in FIG. 2A, comprises a pre-amplification stage (201), a post-amplification stage (203), and a simplified spatial filter (204); the simplified spatial filter (204) comprises beam expanding lenses 2021, 2023. In a conventional amplification and transmission device as shown in FIG. 2B, a spatial filter (202) comprises not only the beam expanding lenses 2021, 2023, but also a spatial filtering aperture 2022. According to the present invention, the spatial filter can be void of the spatial filtering aperture, so that the difficulty in adjusting the laser device is lowered, while the efficiency of targeting by the laser device is improved.

[0060] The frequency conversion unit (3) in the example, as shown in FIG. 3A, performs frequency tripling and specifically comprises a vacuum window (31), a frequency doubling crystal (32), and a frequency tripling crystal (33). In a conventional frequency conversion unit as shown in FIG. 3B, a fundamental-frequency random-phase mask (30) and a frequency-doubling random-phase mask (34) are further included. According to the present invention, the fundamental-frequency random-phase mask (30) and the frequency-doubling random-phase mask (34) are removed, rendering a simpler mechanism so that the difficulty in adjusting the laser device is lowered.

[0061] In the example, the focusing unit (4), as shown in FIG. 4, is an aspherical lens (41).

[0062] FIGS. 5A and 5B shows the output of the laser driving device based on low-spatial-coherence light in the near field (FIG. 5A) and the far field (FIG. 5B) according to the example.

Example 2

[0063] The frequency conversion unit (3) of the example, as shown in FIG. 6, performs frequency quadrupling, and specifically, comprises the vacuum window (31), the frequency doubling crystal (32), the frequency tripling crystal (33), and a frequency quadrupling crystal (35).

[0064] In the example, the focusing unit (4), as shown in FIG. 7, is a wedge-shaped focusing lens (42).

Example 3

[0065] As shown in FIG. 8, the focusing unit (4) in the example comprises a deformable reflective lens (43), a beam deflection lens group (45), and a reflective focusing lens (46).

Example 4

[0066] As shown in FIG. 9, the focusing unit (4) in the example comprises the deformable reflective lens (43), arrayed lenses (44), and an aspheric lens (41).

Example 5

[0067] Example 5 is based on Example 1 and further comprises a collimation component 8, a measurement unit 7, and a control component 9, as shown in FIG. 10. The collimation component 8 collimates each light beam in the laser driving device, the measurement unit 7 measures various signals in the laser driving device, and the control component 8 controls various signals in the laser driver. The collimation component 8, the measurement unit 7, and the control component 9 can assist the laser driving device in targeting with high efficiency and high quality.

Example 6

[0068] The example is based on Example 1 and incorporates a beam shaping component (6) into the amplification and transmission unit (2) as shown in FIG. 11. The light beam shaping component (6) effectively controls intensities and phases of a light beam and comprises a deformable reflective lens (61) and a serrated aperture (62). The amplification and transmission unit (2) comprises a ¼ wave plate (205), a rod-shaped laser head of amplification gain medium (206), a first polarizing beam-splitter prism (207), an intracavity spatial filter (208), a first reflective lens (209), a second polarizing beam-splitter prism (210), a spatial transmission filter (211), a Faraday rotator (212), a second reflective lens (213), and a beam expander (214).

Example 7

[0069] The example is based on Example 1 and incorporates the beam shaping component (6) into the amplification and transmission unit (2) as shown in FIG. 12. The beam shaping component (6) comprises the deformable reflective lens (61). The amplification and transmission unit (2) comprises a first sheet-shaped laser head of amplification gain medium (215), a first spatial filter (216), a second sheet-shaped laser head of amplification gain medium (217), a polarizing emission lens (218), a first total reflection lens (219), a second total reflection lens (220), and a second spatial filter (221).

Example 8

[0070] The spatial transmission device (222) in the amplification and transmission unit (2) in this Example, as shown in FIG. 13, comprises a first lens (2221) and a second lens (2222), and the spatial transmission means (222) is placed behind the laser seed (1) and in front of the spatial filter to narrow the divergence angle of the laser.

[0071] The present invention improves the uniformity of the light field output by the laser driving device, solves the problems of low efficiency of frequency multiplier caused by a broad spectral band and damage to optical elements caused by reduced self-focusing, breaks through the energy limit caused by limited damage resistance capability bearable for ultraviolet elements, increases the overall energy output of the laser driving device, and thus improves the overall efficiency of the laser device.