An optical frequency multiplication device applied to laser internal engraving

Abstract

The application relates to the technical field of laser processing, and discloses an optical frequency multiplication device applied to laser internal engraving, which comprises a shell, a clamp and a crystal. The shell is used for separating the internal temperature from the external temperature, thereby reducing the influence of the external environment on the internal environment. The clamp is installed in the shell and symmetrically distributed above and below and wraps the crystal, and is used for fixing the positions of the crystals and conducting heat. The crystal is arranged between the clamps and is used for converting fundamental frequency laser into frequency multiplication laser. A temperature control mechanism is installed on the side of the clamp far from the crystal, and has the functions of heating and cooling, and is used for increasing or decreasing the temperature of the crystal. A plurality of nonlinear crystals with different geometric cutting angles are placed in the same clamp, and the overall temperature of the clamp is controlled by a temperature control module to be the midpoint of the phase matching temperature of each crystal. When the temperature drifts, the decrease of the frequency multiplication efficiency of part of the crystals can be compensated by the increase of the efficiency of other crystals, so that the stability of the frequency multiplication light output power is effectively improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of laser processing, in particular to an optical frequency doubling device applied to laser internal engraving. BACKGROUND

[0002] The laser internal engraving technology is a high-precision processing method and is widely applied to industrial manufacturing and artistic creation fields. The technology realizes detailed patterns and complex structures by laser beam engraving in the material. Due to the high energy density and good focusing characteristics of the laser, the laser internal engraving can efficiently and accurately process various materials such as glass, wood and metal. However, in order to achieve higher processing quality and efficiency, it is usually necessary to adjust the wavelength of the laser to a range more suitable for the absorption of specific materials. The main function of the optical frequency doubling device is to convert the wavelength of the fundamental frequency laser into a shorter frequency-doubled laser wavelength. Taking the fundamental frequency laser of 1064 nm as an example, the optical frequency doubling device can effectively generate 532 nm laser. The laser of this wavelength is more easily absorbed by many materials, thereby realizing higher processing efficiency and more delicate internal engraving effect. In addition, the application of the frequency-doubled laser in the visible light range also facilitates the alignment and adjustment of the operator.

[0003] However, the existing frequency doubling device usually uses a single nonlinear crystal for frequency conversion, and there are key problems such as insufficient temperature control precision, phase matching problem, output power fluctuation, high structural complexity and insufficient flexibility. Specifically, temperature fluctuations will cause the performance of the crystal to decline, thereby affecting the frequency doubling efficiency; different crystal geometric cutting angles result in different phase matching temperatures, making it difficult to simultaneously meet the matching requirements of multiple crystals; the efficiency decline of a single crystal will directly cause the fluctuation of the overall laser output power, affecting the processing quality. In addition, the existing device is often complex in design and needs to rely on high-precision monitoring and control systems, increasing the overall cost and maintenance difficulty, and lacking adaptability to different laser wavelengths or materials, limiting its use in diversified applications. Therefore, a new type of frequency doubling device is needed to solve the above problems and improve the performance and stability of laser internal engraving. SUMMARY

[0004] In view of the deficiencies of the prior art, the application provides an optical frequency doubling device applied to laser internal engraving, which solves the problem of unstable frequency doubling efficiency caused by temperature fluctuations in laser internal engraving.

[0005] To achieve the above purpose, the application is implemented by the following technical scheme: an optical frequency doubling device applied to laser internal engraving, comprising:

[0006] A housing for separating the internal temperature from the external temperature to reduce the influence of the outside on the inside;

[0007] Clamps, which are installed inside the shell and symmetrically distributed up and down and wrap around the crystals, are used to fix the position between the crystals and conduct heat;

[0008] Crystals, which are arranged between the clamps, are used to convert the fundamental frequency laser into the frequency-doubled laser;

[0009] Temperature control mechanisms, which are installed on the side of the clamps away from the crystals, have both heating and cooling functions, and are used to raise or lower the temperature of the crystals;

[0010] Temperature control modules, which are arranged outside the shell and electrically connected between the temperature control mechanisms, are used to control the operating state of the temperature control mechanisms.

[0011] Preferably, the crystals include but are not limited to fixed-pitch arrangement and bonded contact connection.

[0012] Preferably, the pitch range of the crystals arranged at fixed intervals is 0.5mm-1mm.

[0013] Preferably, when the crystals are arranged at fixed intervals, both light transmission surfaces of the crystals are polished and coated for providing the fundamental frequency laser and frequency-doubled laser irradiation channels.

[0014] Preferably, when the crystals are bonded and contacted, the entrance surface of the first crystal and the exit surface of the last crystal are polished and coated for providing the fundamental frequency laser and frequency-doubled laser irradiation channels.

[0015] A control method of an optical frequency-doubling device applied to laser internal engraving, comprising the following steps:

[0016] S1, configure the crystal array: use multiple nonlinear crystals, set the total number of crystals N, and optimize the cutting according to the geometric cutting angle (θ i ,φ i ) of each crystal;

[0017] S2, set the ideal phase matching temperature: calculate the ideal phase matching temperature T i,opt for each crystal;

[0018] S3, set the target temperature of the whole clamp through the temperature control module: calculate and set the target temperature of the whole clamp as the weighted average of the ideal phase matching temperatures of all crystals.

[0019] Preferably, in the S2 step, the definition formula of the crystal position and the phase matching temperature is:

[0020] When N is odd:

[0021]

[0022] When N is even:

[0023]

[0024] wherein, T i,opt is the ideal phase matching temperature, N is the total number of crystals, and i is the serial number of the crystal.

[0025] Preferably, in the S3 step, the target temperature of the temperature control module is calculated according to the following formula:

[0026]

[0027] wherein, T control is the target temperature of the temperature control module, T i,opt is the ideal phase matching temperature, N is the total number of crystals, and i is the serial number of the crystal.

[0028] Working principle: Before the device is put into operation, the average temperature suitable for the adaptation between the crystals needs to be calculated. After the calculation, the temperature in the clamp is adjusted to the average value by the temperature control module. After the adjustment is completed, the corresponding fundamental frequency laser starts to transmit from the first crystal and finally transmits from the last crystal. When the corresponding temperature deviates during the transmission of the fundamental frequency laser, part of the performance changes, which produces a rising and falling reaction, thereby offsetting the deviation caused by the temperature drift.

[0029] The application provides an optical frequency doubling device applied to laser internal carving.

[0030] 1. The application places multiple nonlinear crystals in the same clamp to form a frequency doubling device. Different crystal geometric cutting angles correspond to different phase matching temperatures. The overall temperature control temperature of the temperature control module is the midpoint of the phase matching temperatures of the crystals. When the crystal temperature drifts, part of the crystals deviate from the phase matching temperature, resulting in a decrease in the frequency doubling efficiency. However, part of the crystals are close to the phase matching temperature, resulting in an increase in the frequency doubling efficiency, so that the decrease is compensated, and therefore the stability of the frequency doubling light output power can be effectively improved as a whole. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a sectional view of the application;

[0032] Figure 2 is a step flowchart of the application.

[0033] wherein, 1, shell; 2, clamp; 3, crystal; 4, temperature control mechanism; 5, temperature control module. DETAILED DESCRIPTION

[0034] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0035] Embodiment one:

[0036] Please refer to the accompanying drawings Figure 1 The embodiment of the present application provides an optical frequency doubling device applied to laser internal carving, which comprises:

[0037] The shell 1 is used to separate the internal temperature from the external temperature, and reduce the influence of the outside on the inside.

[0038] The clamp 2 is installed inside the shell 1 and symmetrically distributed up and down and wraps the crystal 3, which is used to fix the position between the crystal 3 and conduct heat.

[0039] The crystal 3 is arranged between the clamps 2, which is used to convert the fundamental frequency laser into frequency-doubled laser.

[0040] The temperature control mechanism 4 is installed on the side of the clamp 2 away from the crystal 3, and has the functions of heating and cooling, which is used to raise or lower the temperature of the crystal 3.

[0041] The temperature control module 5 is arranged outside the shell 1 and electrically connected between the temperature control mechanism 4, which is used to control the running state of the temperature control mechanism 4.

[0042] The crystal 3 includes but is not limited to fixed-pitch arrangement and bonding contact connection.

[0043] The pitch range of the crystal 3 distributed with fixed pitch is 0.5mm-1mm.

[0044] When the crystal 3 is arranged with fixed pitch, both light transmitting surfaces of the crystal 3 are polished and coated, which is used to provide the irradiation channels of the fundamental frequency laser and the frequency-doubled laser.

[0045] When the crystal 3 is connected by bonding contact, the entrance surface of the first crystal 3 and the exit surface of the last crystal 3 are polished and coated, which is used to provide the irradiation channels of the fundamental frequency laser and the frequency-doubled laser.

[0046] Specifically, before the device is put into operation, the average value of the adaptive temperature between the crystals 3 needs to be calculated first. The setting of this temperature is the key to ensure the efficient operation of the whole optical frequency doubling device. Through the temperature control module 5, the temperature control mechanism 4 can be accurately controlled to adjust the temperature in the clamp 2 to the preset adaptive value. The goal of this process is to achieve the temperature balance between the crystals 3, and to provide an ideal working environment for the subsequent frequency doubling process of the laser.

[0047] After the adjustment is completed, the fundamental laser will be transmitted from the first crystal 3, and after the conversion of each crystal, it will finally be emitted from the last crystal 3. At this time, the wavelength of the laser will be effectively converted from 1064 nm to 532 nm. It is worth noting that during the transmission of the fundamental laser, if the temperature deviates, it may cause the performance of part of the crystal 3 to change, which is manifested as the efficiency of part of the crystal increasing and the efficiency of part of the crystal decreasing, that is, the decrease in the frequency doubling efficiency of part of the crystal is compensated by the increase in the frequency doubling efficiency of part of the crystal;

[0048] This design has important effectiveness, that is, it effectively reduces the power fluctuation as a whole, thereby improving the stability of the frequency-doubled light power. In this way, not only the accuracy of laser processing is improved, but also the adaptability of the system in a changing environment is enhanced. Ultimately, this method will significantly improve the overall processing quality of laser internal engraving and ensure the consistency and reliability of the product.

[0049] Embodiment two:

[0050] Please refer to the accompanying Figure 2 , a control method of an optical frequency doubling device applied to laser internal engraving, comprising the following steps:

[0051] S1, configuring a crystal array: using multiple nonlinear crystals 3, setting the total number of crystals 3 N, and optimizing the cutting according to the geometric cutting angles (θ i , φ i ) of each crystal 3;

[0052] S2, setting the ideal phase matching temperature: calculating the ideal phase matching temperature T i,opt of each crystal 3;

[0053] S3, setting the target temperature of the whole clamp through the temperature control module: calculating and setting the target temperature of the whole clamp 2 as the weighted average of the ideal phase matching temperatures of all crystals 3;

[0054] In the S2 step, the definition formula of the crystal 3 position and the phase matching temperature is:

[0055] When N is odd:

[0056]

[0057] When N is even:

[0058]

[0059] Wherein, T i,opt is the ideal phase matching temperature, N is the total number of crystals 3, and i is the serial number of the crystal 3;

[0060] In the S3 step, the target temperature calculation formula of the temperature control module 5 is:

[0061]

[0062] Where T control is the target temperature of the temperature control module 5, T i,opt is the ideal phase matching temperature, N is the total number of crystals 3, and i is the serial number of the crystal 3.

[0063] Specifically, the S1 step constructs an optical frequency doubling device by using multiple nonlinear crystals 3; the geometric cutting angle of each crystal is optimized to ensure that it can achieve the best phase matching; the optimization of the geometric cutting angle is based on the optical properties of the laser wavelength and the material to ensure maximum conversion efficiency in practical applications; this reasonable crystal configuration not only helps to improve the laser output power, but also improves the machining precision;

[0064] In the S2 step, the ideal phase matching temperature of each crystal 3 is calculated; this temperature is set based on nonlinear optical theory by considering the geometric cutting angle of the crystal and its corresponding wavelength; the ideal phase matching temperature ensures that the light wave maintains the same phase velocity in the crystal at this temperature, thereby maximizing the conversion efficiency; by accurately setting the phase matching temperature of each crystal, the conversion efficiency and overall output quality of the laser can be significantly improved;

[0065] In the S3 step, the target temperature of the temperature control module is set: this step calculates and sets the target temperature of the temperature control module 5, which is the weighted average of the ideal phase matching temperatures of all crystals 3; through this weighted average method, the temperature requirements of each crystal can be effectively integrated, thereby reducing the impact of temperature fluctuations on the overall system; precise control of the temperature control module helps to maintain overall output stability under dynamic operating conditions and ensures consistent quality during laser processing;

[0066] Through the control method, a reasonable crystal 3 configuration, accurate phase matching temperature setting, and effective temperature control mechanism are formed to form an efficient and stable laser frequency doubling system; through the implementation of the above steps, the output power of the frequency-doubled laser can be effectively improved, the power drift caused by temperature changes can be reduced, and the processing quality of the laser internal carving can be improved; this method not only reduces the dependence on high-precision temperature control modules, making the device design simpler and more compact, but also makes it more flexible and economical in practical applications.

[0067] Example Three:

[0068] The frequency doubling device of the present application uses LBO crystals to convert laser with fundamental frequency of 1064 nm to frequency-doubled laser with 532 nm. The device uses 5 LBO crystals, and the specific parameters are as follows:

[0069] Crystal configuration:

[0070] The size of each crystal is 3x3x5mm, in which 5mm is the length of the light transmission direction.

[0071] The light transmission end face of the crystal is polished and coated, and the coating layer is suitable for 1064nm and 532nm antireflection coating.

[0072] Crystal spacing:

[0073] The spacing between each crystal is set to 0.5mm to ensure effective transmission of the light beam.

[0074] Geometric cutting angle and phase matching temperature:

[0075] The first LBO crystal:

[0076] Geometric cutting angle (θ0=90°, φ0=0.8°)

[0077] Phase matching temperature T 1,opt =421.6K

[0078] The second LBO crystal:

[0079] Geometric cutting angle (θ0=90°, φ0=0.7°)

[0080] Phase matching temperature T 2,opt =421.7K

[0081] The third LBO crystal:

[0082] Geometric cutting angle (θ0=90°, φ0=0.6°)

[0083] Phase matching temperature T 3,opt =421.8K

[0084] The fourth LBO crystal:

[0085] Geometric cutting angle (θ0=90°, φ0=0.5°)

[0086] Phase matching temperature T 4,opt =421.9K

[0087] The fifth LBO crystal:

[0088] Geometric cutting angle (θ0=90°, φ0=0.4°)

[0089] Phase matching temperature T 5,opt =422.0K.

[0090] Specifically, the embodiment describes in detail how to use LBO crystal to efficiently realize frequency multiplication of laser, focusing on the configuration, spacing, cutting angle and phase matching temperature of the crystal. This design ensures the stability and efficiency of the laser output, providing a reliable technical solution for the practical application of laser internal carving field. Through reasonable crystal layout and temperature control design, the invented frequency doubling device exhibits good performance and economy in operation, suitable for wide application in industrial and scientific research fields.

[0091] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Modifications can be made by those skilled in the art, particularly in light of the foregoing teachings, without departing from the spirit of the present application. The scope of the present application shall be expressed in the appended claims and their equivalents.

Claims

1. An optical frequency doubling device applied to laser internal engraving, characterized in that, The optical frequency doubling device comprises a shell (1) for separating the internal temperature from the external temperature and reducing the influence of the external environment on the internal environment; a clamp (2) installed inside the shell (1) and symmetrically distributed in up and down directions and wrapping the crystal (3) for fixing the position and conducting heat between the crystals (3); the crystal (3) arranged between the clamps (2) for converting the fundamental frequency laser into the frequency-doubled laser; a temperature control mechanism (4) installed on the side of the clamp (2) away from the crystal (3) and having the functions of heating and cooling for increasing or decreasing the temperature of the crystal (3); and a temperature control module (5) arranged outside the shell (1) and electrically connected with the temperature control mechanism (4) for controlling the running state of the temperature control mechanism (4). The control of the optical frequency doubling device comprises the following steps: S3, setting the target temperature of the whole clamp through the temperature control module: calculating and setting the target temperature of the whole clamp (2) as the weighted average of the ideal phase matching temperatures of all the crystals (3); In the S2 step, the definition formula of the position and the phase matching temperature of the crystal (3) is: The crystal (3) comprises fixed interval arrangement and bonding contact connection. The interval range of the fixed interval distribution of the crystal (3) is 0.5mm-1mm. When the crystal (3) is arranged in the fixed interval, the two light transmission surfaces of the crystal (3) are polished and coated for providing the irradiation channels of the fundamental frequency laser and the frequency-doubled laser. S1, configuring crystal array: adopt multiple nonlinear crystals (3), set the total number of crystals (3) , and optimize the cutting angle according to the geometric cutting angle of each crystal (3) ; S2, setting ideal phase matching temperature: calculate the ideal phase matching temperature for each crystal (3) ; When the crystal (3) is connected in the bonding contact, the incident surface of the first crystal (3) and the emergent surface of the last crystal (3) are polished and coated for providing the irradiation channels of the fundamental frequency laser and the frequency-doubled laser. ​ If even: If even: wherein, is the ideal phase matching temperature, is the total number of crystals (3), is the serial number of the crystal (3).

2. The optical frequency doubling device for laser internal engraving according to claim 1, characterized in that, ​ 3. The optical frequency doubling device for laser internal engraving according to claim 1, characterized in that, ​ 4. The optical frequency doubling device for laser internal engraving according to claim 1, characterized in that, ​ 5. The optical frequency doubling device for laser internal engraving according to claim 1, characterized in that, ​

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