CN117277043B - Light spot superposition homogenizing anhydrous air-cooled laser based on right-angle prism cavity and output method - Google Patents

Abstract

The present invention relates to the field of laser technology, and in particular to a waterless and airless cooling laser and an output method for spot superposition homogenization based on a right-angle prism cavity. A right-angle prism, a gain medium, a saturable absorber, and an output mirror are placed in sequence in the horizontal direction; a pump module is placed in parallel directly above the gain medium; the bottom surface of the right-angle prism is parallel to the end surface of the gain medium, and the ridge of the right-angle prism is 45 degrees to the vertical direction; the output surface of the output mirror is placed parallel to the end surface of the gain medium. The right-angle prism and the output mirror form a resonant cavity. The present invention provides a technical solution for improving the symmetry of the light spot with a simple structure and low cost.

Description

A waterless and airless cooling laser with spot superposition and homogenization based on a right-angle prism cavity and an output method

Technical Field

The invention relates to the technical field of lasers, and in particular to a waterless and airless cooling laser with spot superposition and homogenization based on a right-angle prism cavity and an output method.

Background technique

Laser is an important light source widely used in medical, communication, material processing and other fields. In applications, the symmetry of the spot has a great influence on the quality of the laser beam. However, waterless and airless lasers can only be cooled by conduction, which has poor heat dissipation capacity. Severe thermal effects cause the output laser spot to be long or crescent-shaped, and its beam quality and symmetry are poor. In addition, the imperfection of optical components and the scattering of laser media will also have a negative impact on the symmetry of the output laser spot, further causing the output laser beam quality to deteriorate.

At present, the main methods to improve the symmetry of laser output spot are limiting the laser mode method and improving the symmetry of the pump light field. Limiting the laser mode method requires the introduction of additional optical elements in the laser system, which increases the complexity and cost of the system and also leads to a decrease in output power. Improving the symmetry of the pump light field requires that the pump light has good symmetry when entering the gain medium. This is difficult to achieve for a miniaturized laser system without active heat dissipation. Therefore, there is an urgent need for a technical means to improve the symmetry of the spot that is suitable for water-free and air-free cooling lasers.

Summary of the invention

In order to solve the problems existing in the prior art, the present invention provides a spot superposition and homogenization waterless and airless cooling laser based on a right-angle prism cavity and an output method. A spot superposition and homogenization waterless and airless cooling laser based on a right-angle prism cavity comprises a right-angle prism, a gain medium, a saturable absorber, a pump module, and an output mirror;

The right-angle prism, gain medium, saturable absorber, and output mirror are placed in sequence from left to right along the optical path;

The pump module is placed parallely and directly above the gain medium;

In the initial state, the bottom surface of the right-angle prism is parallel to the end surface of the gain medium and perpendicular to the working optical path, and the ridge surface of the right-angle prism is 45 degrees to the bottom surface;

The output surface of the output mirror is placed parallel to the end surface of the gain medium;

The right-angle prism and the output mirror form a resonant cavity;

Furthermore, each reflective surface in the right-angle prism is coated with a total reflection film of the output laser wavelength.

Furthermore, both ends of the gain medium are coated with anti-reflection films of the output laser wavelength.

Furthermore, the output mirror is coated with an anti-reflection film of the output wavelength.

Furthermore, the saturable absorber is a Cr ⁴⁺ :YAG crystal.

Furthermore, the gain medium is Nd:YAG crystal.

Furthermore, the present invention provides a spot superposition and homogenization waterless and airless cooling laser based on a right-angle prism cavity, which also includes a 45-degree beam splitter, a CCD camera, an information processing device, a stepper motor driver, a data line, and a stepper motor.

The 45-degree beam splitter splits the outgoing laser beam, with one beam being emitted vertically upward and the other being emitted horizontally.

The CCD camera receives the vertical laser beam split by the 45-degree beam splitter and is connected to the information processing device via a data line.

The information processing device is connected to the stepper motor driver and the stepper motor in sequence through data lines;

The stepper motor is connected to the right-angle prism through a pan-tilt platform, so that the roof surface and the bottom surface of the right-angle prism can rotate along the working light path direction, and/or the right-angle prism can be translated to adjust the cavity length of the resonant cavity;

The stepper motor is a three-degree-of-freedom stepper motor, which can realize the pitch angle, roll angle and translation adjustment of the right-angle prism.

According to another aspect of the present invention, a method for outputting laser light and superimposing and homogenizing light spots using the above-mentioned laser is provided, and the method comprises the following steps:

S1: The pump module emits pump light to side-pump the gain medium;

S2: The gain medium absorbs the pump light, energy level transition occurs, and the population inversion is achieved;

S3: The initial transmittance of the saturable absorber is low, the loss in the laser resonant cavity is large, and laser oscillation cannot be formed.

S4: Under the action of pump light, the number of upper energy level particles in the gain medium continues to increase, the laser intensity increases, the transmittance of the saturable absorber increases, the loss in the cavity decreases, and the laser oscillates back and forth in the resonant cavity.

S5: The laser in the resonant cavity is reflected by the right-angle prism, and the light spot rotates 90 degrees.

S6: The laser outputted by the output mirror is incident on the CCD camera through a 45-degree beam splitter. The CCD camera monitors the shape of the output laser spot and transmits the information to the information processing device in real time. The information processing device evaluates the symmetry of the output laser spot.

S7: When the information processing device determines that the output laser spot is asymmetric, the information processing device transmits a signal to the stepper motor driver, and the stepper motor driver controls the stepper motor to rotate a corresponding angle and/or translate a corresponding distance.

S8: When the information processing device determines that the output laser spot is symmetrical, the right-angle prism is adjusted to a final state, and the output laser spot is optimized.

The beneficial effects of the present invention are as follows: since the light spot emitted from the gain medium in the side pumping is not a uniform circular light spot, but a long strip or crescent shape. The present invention replaces the total reflection mirror in the optical resonant cavity with a right-angle prism, and the right-angle side of the right-angle prism is 45 degrees to the vertical direction. After the laser in the resonant cavity is reflected by the right-angle prism, the light spot rotates 90 degrees, and the symmetry of the light spot is improved. Furthermore, the present invention also adds a CCD camera and a stepper motor to adjust the rotation angle of the right-angle prism in real time according to the symmetry of the output light spot. The present invention provides a technical solution for improving the symmetry of the light spot with a simple structure and low cost.

It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

FIG1 is a schematic diagram of a first embodiment of a spot superposition and homogenization waterless and airless cooling laser based on a right-angle prism cavity.

FIG. 2 is a schematic diagram of a second embodiment of a waterless and airless cooling laser based on a right-angle prism cavity and light spot superposition and homogenization.

FIG3 is a schematic diagram of the rotation effect of a right-angle prism light spot.

FIG4 is a working flow chart of a waterless and airless cooling laser with spot superposition and homogenization based on a right-angle prism cavity.

Detailed ways

The present disclosure will now be discussed with reference to several exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and thus implement the present disclosure, rather than implying any limitation on the scope of the present disclosure.

As used herein, the term "including" and variations thereof are to be interpreted as open-ended terms meaning "including but not limited to." The term "based on" is to be interpreted as "based, at least in part, on." The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment." The term "another embodiment" is to be interpreted as "at least one other embodiment."

Embodiment 1

As shown in FIG1 , a first embodiment of a spot superposition homogenization waterless and airless cooling laser based on a right-angle prism cavity of the present invention comprises a right-angle prism 1, a gain medium 2, a saturable absorber 3, a pump module 4, and an output mirror 5;

The right-angle prism 1, the gain medium 2, the saturable absorber 3, and the output mirror 5 are placed in sequence from left to right along the optical path;

The pump module 4 is placed in parallel and directly above the gain medium 2;

In the initial state, the bottom surface of the right-angle prism 5 is parallel to the end surface of the gain medium 2 and perpendicular to the working optical path, and the ridge surface of the right-angle prism 5 is at 45 degrees to the end surface;

The output surface of the output mirror 5 is placed parallel to the end surface of the gain medium 2;

The right angle prism 1 and the output mirror 5 form a resonant cavity;

Each reflective surface in the right-angle prism 1 is coated with a total reflection film of the output laser wavelength;

Both ends of the gain medium 2 are coated with an anti-reflection film of the output laser wavelength;

The output mirror 5 is coated with an anti-reflection film of the output wavelength;

The saturable absorber 3 is a Cr ⁴⁺ :YAG crystal;

The gain medium 2 is Nd:YAG crystal;

As shown in FIG2 , a laser for improving the asymmetry of the output light spot of the present invention further includes a 45-degree beam splitter 6, a CCD camera 7, an information processing device 8, a stepper motor driver 9, a data line 10, and a stepper motor 11;

The 45-degree beam splitter 6 splits the outgoing laser beam, with one beam being emitted vertically upward and the other being emitted horizontally;

The CCD camera 7 receives the vertical laser beam split by the 45-degree beam splitter 6 and is connected to the information processing device via a data line;

The information processing device 8 is connected to the stepper motor driver 9 and the stepper motor 11 in sequence through the data line 10;

The stepper motor 11 is connected to the right-angle prism 1 through a pan-tilt platform, so that the ridge surface and the bottom surface of the right-angle prism 1 can rotate along the working light path direction, and/or the right-angle prism 1 can be translated to adjust the cavity length of the resonant cavity.

According to another aspect of the present invention, a method for outputting laser light and superimposing and homogenizing light spots using the above-mentioned laser is provided, the method comprising the following steps:

S1: Pump module 4 emits pump light to side-pump gain medium 2;

S2: Gain medium 2 absorbs pump light, undergoes energy level transition, and achieves population inversion;

S3: The initial transmittance of saturable absorber 3 is low, the loss in the laser resonant cavity is large, and laser oscillation cannot be formed;

S4: Under the action of pump light, the number of upper energy level particles in the gain medium 2 continues to increase, the laser light intensity increases, the transmittance of the saturable absorber 3 increases, the cavity loss decreases, and the laser oscillates back and forth in the resonant cavity;

S5: The laser in the resonant cavity is reflected by the right-angle prism 1, and the light spot rotates 90 degrees (as shown in Figure 3);

S6: The laser outputted by the output mirror 5 is incident on the CCD camera 7 via the 45-degree beam splitter 6. The CCD camera 7 monitors the shape of the output laser spot and transmits the information to the information processing device 8 in real time. The information processing device 8 evaluates the symmetry of the output laser spot.

S7: When the information processing device 8 determines that the output laser spot is asymmetric, the information processing device 8 transmits a signal to the stepper motor driver 9, and the stepper motor driver 9 controls the stepper motor 11 to rotate a corresponding angle and/or translate a corresponding distance (as shown in FIG. 4 );

S8: When the information processing device 8 determines that the output laser spot is symmetrical, the angle of the right-angle prism 1 is adjusted to the final state, and the output laser spot is optimized (as shown in FIG. 4 );

The working process of a waterless and airless laser with spot superposition and homogenization based on a right-angle prism cavity is shown in FIG4. The CCD camera 7 can collect the laser output spot shape in real time, and transmit the collected spot pattern to the information processing device 8, which analyzes and determines whether the output spot is symmetrical. If it is asymmetrical, the information processing device 8 transmits a signal to the stepper motor driver 9, and the stepper motor driver 9 controls the stepper motor 11 to rotate the corresponding angle to optimize the output spot shape. Repeat the above steps until the spot is symmetrical.

Embodiment 2

Furthermore, in the method for using the laser to output laser light and to superimpose and homogenize the light spot described in the first embodiment, the information processing device 8 in step S6 evaluates the symmetry of the output laser light spot, which specifically includes the following steps:

S61: Evaluate the symmetry of the laser spot by using a software system pre-installed in the information processing device 8;

S62: The laser spots include the following TEM ₀₀ , TEM ₀₁ , TEM ₁₀ , TEM ₁₁ , TEM ₀₂ , TEM ₂₀ , TEM ₁₂ , TEM ₂₁ , TEM ₂₂ . . . TEM _ab (a≥0, b>2 or a＞2, b≥0) modes.

In step S7, the stepper motor driver 9 controls the stepper motor 11 to rotate a corresponding angle and/or translate a corresponding distance, which specifically includes the following steps:

S71: When the information processing device 8 evaluates that the laser spot is in the TEM ₀₁ , TEM ₁₀ , TEM ₁₁ mode, the stepper motor driver 9 controls the stepper motor 11 to rotate a corresponding angle in the pitch angle direction; when the information processing device 8 evaluates that the laser spot is in the TEM ₀₂ , TEM ₂₀ , TEM ₁₂ , TEM ₂₁ , TEM ₂₂ ...TEM _ab (a≥0, b>2 or a＞2, b≥0) mode, the stepper motor driver 9 controls the stepper motor 11 to rotate a corresponding angle in the pitch angle direction, and/or translate a corresponding distance;

S72: Evaluate the laser spot in real time by the information processing device 8;

S73: If the laser spot is in TEM ₀₀ mode, execute step S8;

S74: If the laser spot is not in the TEM ₀₀ mode, the stepper motor driver 9 controls the stepper motor 11 to rotate a corresponding angle in the roll angle direction and/or translate a corresponding distance;

S75: Evaluate the laser spot in real time by the information processing device 8;

S76: Repeat steps S71-S75 until the output laser spot is in TEM ₀₀ mode.

It is to be understood that in the present disclosure, "plurality" refers to two or more than two, and other quantifiers are similar thereto. "And/or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and/or B may represent: A exists alone, A and B exist at the same time, and B exists alone. The character "/" generally indicates that the associated objects before and after are in an "or" relationship. The singular forms "a", "the" and "the" are also intended to include plural forms, unless the context clearly indicates other meanings.

It is further understood that the terms "first", "second", etc. are used to describe various information, but such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other, and do not indicate a specific order or degree of importance. In fact, the expressions "first", "second", etc. can be used interchangeably. For example, without departing from the scope of the present disclosure, the first information can also be referred to as the second information, and similarly, the second information can also be referred to as the first information.

It will be further understood that the terms “center”, “longitudinal”, “lateral”, “front”, “back”, “up”, “down”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present embodiment and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation.

It can be further understood that, unless otherwise specified, “connection” includes a direct connection without other components between the two, and also includes an indirect connection with other components between the two.

It is further understood that, although the operations are described in a specific order in the drawings in the embodiments of the present disclosure, it should not be understood as requiring the operations to be performed in the specific order shown or in a serial order, or requiring the execution of all the operations shown to obtain the desired results. In certain environments, multitasking and parallel processing may be advantageous.

Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the disclosure disclosed herein. The present disclosure is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art that are not disclosed in the present disclosure. The description and examples are to be considered exemplary only, and the true scope and spirit of the present disclosure are indicated by the following claims.

It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims (8)

1. A waterless and airless cooling laser based on a right-angle prism cavity for spot superposition and homogenization, characterized in that: The invention comprises: a right-angle prism (1), a gain medium (2), a saturable absorber (3), a pump module (4), and an output mirror (5); wherein the right-angle prism (1), the gain medium (2), the saturable absorber (3), and the output mirror (5) are arranged in sequence from left to right along the optical path; The pump module (4) is placed in parallel and directly above the gain medium (2); In an initial state, the bottom surface of the right-angle prism (1) is parallel to the end surface of the gain medium (2) and perpendicular to the working optical path, and the ridge surface of the right-angle prism (1) is at 45 degrees to the bottom surface; The output surface of the output mirror (5) is placed parallel to the end surface of the gain medium (2); The right-angle prism (1) and the output mirror (5) form a resonant cavity; It also includes a 45-degree beam splitter (6), a CCD camera (7), an information processing device (8), a stepper motor driver (9), a data cable (10), and a stepper motor (11); The 45-degree beam splitter (6) splits the emitted laser light, with the first light path being emitted vertically upward and the second light path being emitted horizontally; The CCD camera (7) receives the vertical laser beam split by the 45-degree beam splitter (6) and is connected to the information processing device via a data line; The information processing device (8) is connected to the stepper motor driver (9) and the stepper motor (11) in sequence via the data line (10); The stepping motor (11) is connected to the right-angle prism (1) via a pan-tilt platform, so that the ridge surface and the bottom surface of the right-angle prism (1) can rotate along the direction of the working light path, and/or the right-angle prism (1) can be translated to adjust the cavity length of the resonant cavity. 2. The spot superposition homogenization waterless and airless cooling laser based on the right-angle prism cavity according to claim 1, characterized in that each reflective surface in the right-angle prism (1) is coated with a total reflection film of the output laser wavelength. 3. The spot superposition homogenization waterless and airless cooling laser based on a right-angle prism cavity according to claim 1, characterized in that both ends of the gain medium (2) are coated with an anti-reflection film of the output laser wavelength. 4. The spot superposition homogenization waterless and airless cooling laser based on a right-angle prism cavity according to claim 1, characterized in that the stepper motor (11) is a three-degree-of-freedom stepper motor, which can achieve the pitch angle, roll angle and translation adjustment of the right-angle prism (1). 5. The water-free and air-free cooling laser with spot superposition and homogenization based on a right-angle prism cavity according to claim 1, characterized in that the output mirror (5) is coated with an anti-reflection film of the output wavelength. 6. The spot superposition homogenization waterless and airless cooling laser based on a right-angle prism cavity according to claim 3, characterized in that the saturable absorber (3) is a Cr ⁴⁺ :YAG crystal. 7. The spot superposition homogenization waterless and airless cooling laser based on a right-angle prism cavity according to claim 5, characterized in that the gain medium (2) is a Nd:YAG crystal. 8. A method for outputting a waterless and airless laser by light spot superposition and homogenization based on a right-angle prism cavity, using the waterless and airless laser by light spot superposition and homogenization based on a right-angle prism cavity as claimed in any one of claims 1 to 7, characterized in that the method comprises the following steps: S1: the pump module (4) emits pump light to side-pump the gain medium (2); S2: The gain medium (2) absorbs the pump light, undergoes energy level transition, and realizes population inversion; S3: The saturable absorber (3) has a low initial transmittance, and the loss in the laser resonant cavity is large, so laser oscillation cannot be formed; S4: Under the action of the pump light, the number of upper energy level particles in the gain medium (2) increases continuously, the laser light intensity increases, the transmittance of the saturable absorber (3) increases, the cavity loss decreases, and the laser oscillates back and forth in the resonant cavity; S5: The laser in the resonant cavity is reflected by the right-angle prism (1), and the light spot is rotated 90 degrees; S6: The laser output by the output mirror (5) is incident on the CCD camera (7) via the 45-degree beam splitter (6); the CCD camera (7) monitors the shape of the output laser spot and transmits the information to the information processing device (8) in real time; the information processing device (8) evaluates the symmetry of the output laser spot; S7: When the information processing device (8) determines that the output laser spot is asymmetric, the information processing device (8) transmits a signal to the stepper motor driver (9), and the stepper motor driver (9) controls the stepper motor (11) to rotate a corresponding angle and/or translate a corresponding distance; S8: When the information processing device (8) determines that the output laser spot is symmetrical, the right-angle prism (1) is adjusted to a final state, and the output laser spot is optimized.