An optical window for a laser igniter

Abstract

The utility model discloses an optical window for a laser igniter, comprising a laser diode for ignition, a laser igniter shell, a primary window and a secondary window; the main body of the laser igniter shell comprises a hole penetrating the entire main body, the primary window and the secondary window are separated by an attenuator, wherein the primary window and the secondary window are coaxial and have the same radial size, the attenuator is coaxial with the primary window and the secondary window and has a smaller radial size than the primary window and the secondary window, and the design of the optical window ensures that the transmission detonation in the laser ignition device does not destroy the pressure integrity of the device; the right end face of the secondary window is coated with a mirror coating and a protective coating in sequence, the mirror coating and the protective coating are coaxial with the secondary window, the mirror coating reflects incident stray light and detection laser, thereby improving the safety and reliability of the igniter; the protective coating plays a role in passivating the mirror coating, and both the mirror coating and the protective coating can be ablated by the ignition laser.

Description

Technical Field

[0001] The utility model belongs to the technical field of laser ignition, and in particular relates to an optical window for a laser igniter. Background Art

[0002] Laser pyrotechnics, as a type of pyrotechnic with high electromagnetic safety, are becoming more and more widely used. They transmit laser energy to output charges through optical fibers to achieve ignition and detonation of pyrotechnic agents.

[0003] As the core transducer component of laser pyrotechnics, the glass window is a high-pressure window component formed by a glass plug or alloy solder and a metal shell. In the laser ignition system, it is required to detect the continuity of the optical path, and the transducer assists in completing functions such as internal self-test; at the same time, during the ignition of the pyrotechnics, the transducer gathers laser energy and detonates the agent. In pressurized applications such as rocket engines, the required functional reliability requires checking the integrity of the system before starting; when using explosive materials such as hexanitrostilbene (HNS), RDX, PETN or other materials, the pressure of the explosion can easily cause the window of the traditional design to break. Therefore, in view of the requirements of high reverse pressure environment and internal self-test of engine ignition, the design of the glass window and the quality of its plug performance not only directly affect the efficiency of laser ignition, but also have a direct impact on the effect of the pyrotechnics, especially the safety in high reverse pressure environment. Utility Model Content

[0004] The utility model provides an optical window for a laser igniter, which solves the problem that the device cannot ensure its airtightness under high-voltage ignition conditions and the traditional laser igniter cannot isolate stray light, detect laser and output charge.

[0005] In order to solve the above technical problems, the utility model provides an optical window for a laser igniter, which is characterized by comprising a laser diode, a laser igniter housing, a primary window, an attenuator, a secondary window, a mirror coating, and a protective coating; the laser igniter housing is provided with a primary window, an attenuator, and a secondary window in sequence from the front end to the rear end, and the rear end surface of the secondary window is provided with a mirror coating and a protective coating in sequence.

[0006] Beneficial effects: The utility model has an attenuator design, and the two-stage window ensures that the pressure sealing performance of the optical window and the device is not destroyed when the laser igniter ignites at high pressure; the ignition laser passes through the primary window, the attenuator and the secondary window and is focused to the rear surface of the secondary window. The mirror coating on the rear surface of the secondary window ensures that stray light and detection laser will not reach the pyrotechnic agent, meeting the design criteria for the safety of the laser igniter; the mirror coating is coated with a protective coating to achieve protection and passivation of the mirror coating. When the coating coated at the end of the secondary window is ablated and evaporated by the ignition laser, the evaporation product promotes and strengthens the ignition of the pyrotechnic agent triggered by the ignition laser beam, ensuring the ignition reliability of the laser igniter. The specific advantages are as follows:

[0007] (1) The optical window for a laser igniter of the utility model can realize the sealing of the device under high-pressure ignition conditions, thereby ensuring the safety of the laser igniter in pressurized applications such as rocket engines;

[0008] (2) The primary window and the secondary window in the utility model are connected by an attenuator, which has the function of absorbing and attenuating the explosion shock, ensuring that the primary window and the pressure-sealed device will not fail under high-pressure ignition conditions;

[0009] (3) The rear surface of the secondary window in the utility model is coated with a mirror reflection layer, which has the function of reflecting stray light and detecting laser light, avoiding accidental ignition while assisting in completing optical path detection, and a protective coating is coated on the rear surface of the mirror coating;

[0010] (4) The protective coating in the present invention has the function of protecting and passivating the mirror coating. The mirror coating and the protective coating are ablated by the ignition laser during ignition, which promotes and strengthens the ignition of the pyrotechnic agent and ensures the ignition reliability of the laser igniter. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a schematic diagram of the optical window implementation of the laser igniter;

[0012] Figure 2 Schematic diagram of the secondary window implementation in the optical window of the laser igniter. DETAILED DESCRIPTION

[0013] In order to make the purpose, content and advantages of the utility model clearer, the specific implementation methods of the utility model are further described in detail below.

[0014] The utility model proposes an optical window for a laser igniter, comprising a laser diode 1, a laser igniter housing 2, a primary window 3, an attenuator 4, a secondary window 5, a mirror coating 6, and a protective coating 7; wherein the laser igniter housing comprises a front end hole 8 for fixing an optical fiber connector, a rear end hole 9 for pressing an output charge, and a lead sealing hole 10.

[0015] The laser diode 1 is used to stimulate the ignition of the output charge. The emitted ignition laser passes through the primary window 3, the attenuator 4, the secondary window 5, the mirror coating 6 and the protective coating 7 of the secondary window in turn to reach the output charge pressed at the rear end of the laser igniter housing. The wavelength of the typical commercially available laser diode is 808nm, 915nm or 976nm. The laser diode 1 is used to complete the optical path detection. The emitted detection laser passes through the primary window 3, the attenuator 4, the secondary window 5 in turn and then is reflected by the mirror coating 6 to reach the laser power meter. A commercially available 1310nm or 1550nm laser can be selected.

[0016] The main body of the laser igniter housing 2 includes a coaxial hole running through the entire main body, providing an optical channel from the laser light source to the output charge; the coaxial hole running through the entire main body has different inner diameter distributions, and the coaxial hole is provided with a primary window 3, an attenuator 4, and a secondary window 5 from the front end to the rear end, and the rear end surface of the secondary window 5 is provided with a mirror coating 6 and a protective coating 7 in sequence; the front end hole 8 of the laser igniter housing is installed with an optical fiber connector, and the rear end hole 9 is a charge cavity for press-fitting the output charge, and the rear end of the housing 2 has an external thread for connecting to the next-level device.

[0017] The primary window 3 is a self-focusing lens, which has a front surface and a rear surface, the rear surface is in contact with the attenuator 4 and is positioned by the attenuator 4; the radial dimensions of the primary window 3 and the secondary window 5 are the same; the ignition laser from the laser diode 1 is received and transmitted to the attenuator 4 in sequence, and after the secondary window 5 is focused to the rear end face of the secondary window 5, it acts on the mirror coating 6 and the protective coating 7 to drive the output charge to generate output; the primary window 3 transmits the detection laser to the attenuator 4, and receives the detection laser reflected by the mirror coating 6 and transmits it to the laser power meter; the pitch of the primary window 3 should ensure that the ignition laser and the detection laser are focused on the mirror coating 6 and the protective coating 7 of the secondary window after passing through the attenuator 4 and the secondary window 5; the primary window 3 is interference fit with the housing 2, and when in use, an interference fit sealing ring or a low melting point glass can be used for sealing to ensure the sealing performance of the laser igniter; the primary window 3 is a high temperature resistant solid transparent block material such as glass, quartz, diamond, cubic zirconia and yttrium aluminum garnet (YAG).

[0018] The rear surface of the attenuator 4 is in contact with the secondary window 5; it receives the ignition laser from the laser diode 1 and the primary window 3, transmits it to the secondary window 5 and focuses it to the rear end face of the secondary window 5, acts on the mirror coating 6 and the protective coating 7, and drives the output charge to generate output; the radial size of the attenuator 4 is smaller than the primary window 3 and the secondary window 5, and the primary window 3 and the secondary window 5 are positioned in the shell 2; it receives the detection laser and transmits it to the secondary window 5; and it receives the detection laser reflected by the mirror coating 6 and transmits it to the laser power meter; the material of the attenuator 4 includes: air, epoxy resin, acrylic resin, polycarbonate or a mixture of these substances. The attenuator 4 is used to weaken and absorb the vibration and shock wave generated when the igniter is ignited, so that the energy of the shock wave is dissipated to a level that will not damage the primary window and the sealing of the device.

[0019] The secondary window 5 is as follows Figure 2 As shown, its front surface is in contact with the attenuator 4 and is positioned by the attenuator 4, and the rear surface is coated with a mirror coating 6 and a protective coating 7 and is in contact with the output charge; it receives the ignition laser from the laser diode 1, the primary window 3 and the attenuator 4, focuses it to the rear surface, acts on the mirror coating 6 and the protective coating 7, and drives the output charge to generate output; it receives the detection laser transmitted to the mirror coating 6, and receives the detection laser reflected by the mirror coating 6 and transmits it to the laser power meter; the secondary window 5 is a transparent substrate, which provides structural support for the optical window.

[0020] The mirror coating 6 is coated on the rear surface of the secondary window 5, and the rear surface of the mirror coating 6 is in contact with the protective coating 7; it receives the ignition laser from the laser diode 1, the primary window 3, the attenuator 4 and the secondary window 5, acts on the protective coating 7 after being ablated by the ignition laser, and drives the output charge to generate output; it receives the detection laser and reflects it to the secondary window 5, the attenuator 4, the primary window 3 in sequence, and transmits it to the laser power meter; the reflectivity of the mirror coating 6 to the detection laser is greater than 90%.

[0021] The protective coating 7 is coated on the rear surface of the mirror coating 6, and the rear surface of the protective coating 7 is in contact with the output charge; it receives the ignition laser from the laser diode 1, the primary window 3, the attenuator 4 and the secondary window 5, and after being ablated by the ignition laser, drives the output charge to generate output; the protective coating 7 is an ablative metal, which protects the mirror coating 6 from aging, and in practical applications it can be an organic material such as silicon oxide or silicone resin plastic.

[0022] The working process of an optical window for a laser igniter is that when the device realizes the ignition function, the ignition laser passes through the primary window 3, the attenuator 4, the secondary window 5, the ablation mirror coating 6 and the protective coating 7 in sequence to reach the output charge, thereby realizing the ignition of the laser igniter; in this process, the attenuator 4 weakens and absorbs the vibration and shock wave generated during the ignition process of the igniter, thereby protecting the integrity of the primary window and the airtightness of the device; when the detection function is realized, the mirror coating 6 can realize the reflection of the detection laser and transmit it back to the laser power meter; in this process, the detection laser and the output charge are isolated, thereby ensuring the safety of the laser igniter.

[0023] The utility model provides an optical window of a laser igniter, which has the functions of transmitting and focusing ignition laser and reflecting detection laser. The secondary optical window has high pressure bearing capacity under high-pressure ignition conditions, the ability to isolate stray light, detection laser and output charge, and the ability to enhance the output ignition of the device due to the ablation and evaporation of the coating when receiving the ignition laser, thereby improving the reliability and safety of the laser igniter in the ignition and detection process, and has application potential in pressurized environments such as rocket engines.

[0024] The utility model solves the problem that the device cannot ensure its airtightness under high-pressure ignition conditions, and the traditional laser igniter cannot isolate stray light, detection laser and output charge. An optical window composed of a primary window, an attenuator and a secondary window is designed to ensure the high-pressure sealing of the laser igniter and achieve the isolation of stray light, detection laser and output charge; at the same time, the double-layer coating design of the secondary window can be ablated by the ignition laser while reflecting the detection laser, thereby promoting and strengthening the ignition of the pyrotechnic agent, ensuring the ignition safety and reliability of the laser igniter, and meeting the application in pressurized environments such as rocket engines.

[0025] The primary window and the secondary window of the utility model are separated by an attenuator, wherein the primary window and the secondary window are coaxial and have the same radial size, the attenuator is coaxial with the primary window and the secondary window and has a smaller radial size than the primary window and the secondary window, and the design of the optical window ensures that the detonation is transmitted in the laser ignition device without destroying the pressure integrity of the device; the right end face of the secondary window is coated with a mirror coating and a protective coating in sequence, the mirror coating and the protective coating are coaxial with the secondary window, and the mirror coating reflects the incident stray light and the detection laser, thereby improving the safety and reliability of the igniter; the protective coating plays the role of passivating the mirror coating, and both the mirror coating and the protective coating can be ablated by the ignition laser. The front end of the optical window of the utility model receives laser energy, and the laser can act on the primary window, the attenuator and the secondary window through the optical fiber connector, and focus on the rear surface of the secondary window, and the output charge is pressed at the rear end of the laser igniter to realize laser ignition and output. In the utility model, the protective coating of the secondary window is directly in direct contact with the output charge, thereby improving the ignition reliability.

[0026] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. An optical window for a laser igniter, characterized in that: It includes a laser diode, a laser igniter housing, a primary window, an attenuator, a secondary window, a mirror coating, and a protective coating; the laser igniter housing is provided with a primary window, an attenuator, and a secondary window from the front end to the rear end, and the rear end surface of the secondary window is provided with a mirror coating and a protective coating in sequence.

2. The optical window for a laser igniter according to claim 1, characterized in that: The laser diode wavelength is 808nm, 915nm or 976nm.

3. The optical window for a laser igniter according to claim 1, characterized in that: The main body portion of the laser igniter housing includes a coaxial bore extending through the entire main body portion.

4. The optical window for a laser igniter according to claim 3, characterized in that: The coaxial bores extending throughout the body portion have different inner diameter distributions.

5. The optical window for a laser igniter according to claim 1, characterized in that: The laser igniter housing comprises a front end hole for fixing the optical fiber connector and a rear end hole for pressing and installing the output charge.

6. The optical window for a laser igniter according to claim 1, characterized in that: The rear end of the laser igniter housing is provided with an external thread for connecting with a next-level device.

7. The optical window for a laser igniter according to claim 1, characterized in that: The primary window adopts a self-focusing lens, the rear surface of which contacts with the attenuator and is positioned by the attenuator; the rear surface of the attenuator contacts with the secondary window.

8. The optical window for a laser igniter according to claim 1, characterized in that: The radial dimensions of the primary window and the secondary window are the same.

9. The optical window for a laser igniter according to claim 1, characterized in that: The pitch of the primary window ensures that the ignition laser and the detection laser are focused onto the mirror coating and protective coating of the secondary window after passing through the attenuator and the secondary window.

10. The optical window for a laser igniter according to claim 1, characterized in that: The radial dimension of the attenuator is smaller than the primary window and the secondary window.

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