Description:4. DESCRIPTION
Technical Field of the Invention

The present invention relates to the field of electronics and communications, with a particular focus on laser-based communication systems. More specifically, it involves a laser unit designed to interact with a target unit, enabling simulated training exercises for military personnel.

Background of the Invention

In the domain of laser-based communication systems, particularly those employed in training simulations for military applications, there is a pressing need to develop highly accurate, reliable, and efficient systems for target engagement and weapon alignment. For military personnel, training is essential to prepare them for real-world combat scenarios. Traditional methods, including live-fire exercises, though effective, come with significant drawbacks: they require large amounts of ammunition, strict safety protocols, and space, which can limit the frequency of training sessions. Moreover, such exercises carry an inherent risk of injury due to the intensity of the drills and the use of live ammunition. The logistical and financial constraints associated with live-fire exercises make them an inefficient and expensive training method.

Furthermore, the use of traditional simulation techniques such as paintball or airsoft, while safer, has its own limitations. These systems fail to replicate the precision and realism of real-life combat situations. The impact of paintball or airsoft projectiles is relatively benign, lacking the accuracy and feedback necessary for effective skill development in target engagement scenarios. Laser-based systems, such as laser tag, provide some level of improvement by mimicking shooting, but they still fall short of offering the high degree of precision, feedback, and scalability required by modern military training programs.

Another significant issue is the limited adaptability of current laser-based systems to different training conditions. These systems often do not account for environmental factors, such as changes in weather, visibility, or terrain, all of which can significantly affect the performance of both the training equipment and the trainees themselves. Such systems are also typically limited by their range and the need for manual realignment, which reduces the efficiency and scalability of training exercises.

To address these limitations, several advancements in the field of laser-based training systems have been made. Various prior art systems have focused on improving the alignment, targeting, and accuracy of laser-based equipment. Some of these systems employ multi-beam approaches, where different laser beams are used for different purposes, such as simulation and alignment. However, none of these systems fully address the problem of integrating visible and infrared (IR) laser beams into a single coherent system capable of delivering high-precision targeting and alignment.

For instance, US20120171643A1 discloses an alignment device for weapons that aims to align a simulation beam with the weapon’s sight. The device uses an optical setup within a housing that projects the alignment beam onto a projection screen, visible through the weapon’s sight. However, this system is limited in its ability to achieve precise, dynamic targeting in real-time conditions. It also does not address the challenge of integrating multiple laser wavelengths for a more flexible and accurate training experience.

US20150377588A1 presents an improved method and apparatus for aligning laser and optical systems over long distances, using reflective materials with markings that reflect light back along the same angle of incidence to help with alignment. While this system helps in aligning laser systems over a distance, it does not offer a method for combining multiple beams into a single, high-precision output, which would be necessary for military training simulations requiring realistic feedback and dynamic interaction.

US20180259295A1 outlines a laser device designed to aim firearms by emitting multiple wavelengths of light. The system uses a collimator to adjust the collimation of light for different wavelengths. This technology offers a solution for adjusting the focus for different wavelengths of light; however, it does not address the challenge of merging multiple laser beams, such as combining visible and infrared light, into a single, unified beam that can provide accurate feedback in dynamic, real-time training scenarios.

Additionally, US6887079B1 describes an alignment device for weapon-mounted simulators, which is effective in aligning a weapon’s sight with the simulator’s beam. However, it too is limited by the inability to integrate and merge multiple wavelengths of light in a compact, efficient system that can be dynamically adjusted for varying conditions. Similar prior technologies, such as US20040076928A1, offer improvements in alignment, but they also fail to provide a system that integrates visible and infrared lasers for more accurate and reliable training applications.

While prior art systems have addressed some of the challenges associated with laser-based training simulations, they still suffer from significant drawbacks. One of the major limitations is the lack of integration of visible and infrared (IR) laser sources into a single, coherent system. Many existing systems use either visible or IR lasers, but not both simultaneously, which significantly reduces their effectiveness in real-world training scenarios. The integration of visible and IR laser beams into a unified system can provide better training feedback and increase the system's flexibility in dynamic and varied environmental conditions.

Another issue is the lack of effective beam alignment and merging mechanisms. Prior technologies, while improving alignment accuracy, often require manual adjustments or are susceptible to misalignment under varying conditions such as temperature changes, humidity, or physical movement. This makes it difficult to maintain the precision of the system, which is essential for realistic training. Moreover, current systems often do not provide sufficient feedback to the trainees regarding their performance, further limiting their effectiveness.

The coatings and materials used in the prior systems also present challenges. For instance, most systems rely on simple coatings that may not provide the desired level of reflectivity and transmission at different wavelengths. This results in losses in efficiency, reducing the overall performance of the system. In some cases, the coatings may not be durable enough to withstand environmental stressors such as moisture, dust, or temperature variations, further complicating their use in real-world training applications.

Lastly, many prior systems have been bulky and difficult to integrate into compact systems. The systems often require large, complex mechanical components, which can reduce portability and limit their scalability for use in large training environments or for multiple simulators operating simultaneously. The lack of modularity and adaptability to various training scenarios further restricts the effectiveness of these technologies.

The inventors of the present system identified a clear and urgent need for a more efficient, adaptable, and precise solution to address the limitations of existing laser-based training systems. The main need identified is for a system that can seamlessly integrate both visible and infrared laser beams into a single, unified output, thereby eliminating the need for multiple beam systems and enhancing targeting accuracy. By using a long pass filter system that allows for the transmission of infrared light while reflecting visible light, the system enables the effective combination of both laser types without interference. This technology will allow military training systems to provide more realistic, dynamic, and accurate simulations.

Moreover, the inventors recognized that a key challenge for existing systems is the inability to maintain alignment and precision over extended distances or under changing environmental conditions. The present invention solves this problem by employing a compliant monolithic structure to precisely position and align the laser beams with minimal deviation. This design ensures that the system remains stable and accurate, even when exposed to external factors like temperature fluctuations or movement. The use of adjustable azimuth and elevation mirrors further ensures that the system can dynamically steer the combined laser beam to provide precise targeting for real-time applications.

Another critical need identified was the durability and reliability of the coatings and materials used in laser systems. Existing systems often suffer from efficiency losses due to suboptimal coatings that fail to achieve the required reflectivity and transmission rates. The inventors addressed this issue by developing a multi-layer anti-reflective coating comprising SiO₂, TiO₂, and Al₂O₃, which significantly improves both the optical efficiency and durability of the filter. This multi-layer coating provides the required spectral performance by reflecting light at 625 nm and transmitting light at 930 nm, with minimal reflection losses and enhanced transmission efficiency for the target wavelengths.

Finally, the inventors realized the need for a system that is compact, scalable, and easy to maintain. The invention incorporates a modular design that makes it easier to integrate into various training systems and environments. The system is also designed for easy recalibration and maintenance, ensuring that it can be used over extended periods without requiring complex disassembly or costly repairs.

By addressing these needs, the inventors aim to revolutionize laser-based training systems, providing a more accurate, reliable, and flexible solution that can better simulate real-world combat conditions while ensuring the safety and effectiveness of military personnel training.

Brief Summary of the Invention

One of the primary objectives of the present invention is to provide a long pass filter system capable of efficiently combining and discriminating light at different wavelengths. This system integrates visible and infrared (IR) laser beams by selectively reflecting and transmitting light at specific wavelengths. This integration is achieved by employing a carefully designed multi-layer anti-reflective coating, which ensures the system delivers the required optical performance. The coating is engineered to reflect light at approximately 625 nm (visible light) and transmit light at approximately 930 nm (IR light), thereby allowing optimal spectral performance that enhances the precision and reliability of the system.

A significant object of this invention is to minimize reflection losses and maximize transmission efficiency for the target wavelengths, making it suitable for various applications, particularly in laser systems, imaging systems, and optical instruments requiring precise wavelength discrimination. The multi-layer coating on the substrate is engineered to optimize its performance by using a specific layering arrangement. The alternating layers of silicon dioxide (SiO₂) and titanium dioxide (TiO₂) are designed to create constructive interference at the reflection wavelength, improving the filter's optical efficiency and ensuring the highest quality output in terms of both reflection and transmission.

Another key objective of the invention is to enhance the durability of the long pass filter by using aluminum oxide (Al₂O₃) in the multi-layer coating. This layer provides additional mechanical robustness and chemical resistance, ensuring that the filter can withstand environmental factors such as moisture, dust, and exposure to various chemicals. The system is thus suitable for applications that require long-term stability, reliability, and resistance to wear and tear under diverse operating conditions.

A further objective of the invention is to enable precision in the manufacturing of the long pass filter, ensuring that each layer in the multi-layer coating is deposited with the utmost accuracy. The method of manufacturing the filter incorporates advanced techniques such as Ion Beam Sputtering (IBS), Electron Beam Evaporation (EBE), and Plasma Enhanced Chemical Vapor Deposition (PECVD), which control the thickness and consistency of each coating layer. A stringent quality control process is employed during manufacturing to measure the filter's optical properties, ensuring that the filter meets the required reflection and transmission specifications before final assembly.

The invention also seeks to provide a compact and scalable solution that can be easily integrated into various systems, including military training simulators, medical diagnostic equipment, and imaging systems. The system’s modular design allows for easy customization and adaptation, making it an ideal solution for diverse applications. Furthermore, the manufacturing process is designed to be cost-effective, enabling large-scale production of high-quality filters without compromising on performance.

The present invention relates to a long pass filter system specifically designed for integrated laser units (ILU) that merge visible and infrared (IR) laser beams for various applications. The invention aims to provide an advanced optical system capable of reflecting visible light and transmitting IR light simultaneously, thus enabling more accurate and realistic simulations in training systems, particularly for military training, imaging, and diagnostic systems.

The long pass filter system consists of a substrate made from high optical clarity and durable materials such as BK7 glass or fused silica, known for their optical and mechanical properties. The substrate supports a multi-layer anti-reflective coating designed to optimize the filter's ability to reflect and transmit light at predetermined wavelengths. The coating is made up of layers of silicon dioxide (SiO₂), titanium dioxide (TiO₂), and aluminum oxide (Al₂O₃). Each material is carefully selected for its optical properties: SiO₂ provides low refractive index properties, TiO₂ offers high refractive index for increased reflectivity, and Al₂O₃ enhances the durability of the coating by improving chemical and mechanical resistance.

The multi-layer anti-reflective coating is engineered to reflect light at approximately 625 nm (visible light) and transmit light at approximately 930 nm (IR light). This specific arrangement allows the filter to act as a long pass filter, efficiently merging the visible and infrared laser beams, which is crucial for applications requiring precise wavelength discrimination.

The manufacturing of the long pass filter system involves several steps to ensure high precision and performance. The first step involves selecting the appropriate substrate made from BK7 glass or fused silica, which are both known for their high optical clarity and mechanical durability. The next step involves depositing the multi-layer anti-reflective coating on the substrate using advanced deposition techniques such as Ion Beam Sputtering (IBS), Electron Beam Evaporation (EBE), or Plasma Enhanced Chemical Vapor Deposition (PECVD). These methods ensure that each layer of the coating is deposited with high accuracy, optimizing its optical properties.

Following the deposition of the coating, the filter undergoes a quality control process where its optical properties, including reflectivity and transmissivity, are tested to ensure they meet the required specifications. The quality control process ensures that the filter meets performance criteria such as a reflection coefficient greater than 90% at 625 nm and a transmission coefficient greater than 85% at 930 nm.

Additionally, a protective surface coating is applied to enhance the anti-reflective properties of the filter and to ensure its durability against environmental factors like moisture, dust, and chemicals. After the coating has been applied and quality control checks are passed, the long pass filter is ready for final integration into laser systems, imaging systems, or training simulators.

The long pass filter system is designed to be integrated into various optical systems. For instance, in laser systems, the filter allows for the merging of visible and infrared laser beams, providing a high-precision output that is critical for applications such as target engagement simulations and real-time laser communications. The filter’s ability to transmit IR light and reflect visible light is key to ensuring that both beams are combined efficiently, which is particularly useful in military training simulations that rely on accurate beam alignment for training and assessment.

In imaging systems, the filter can be used to enhance the spectral performance of the system by allowing specific wavelengths of light to pass through while blocking others. This is beneficial for applications requiring specific wavelength discrimination, such as medical imaging and remote sensing.

The system is also adaptable for use in training simulators, particularly military applications, where it can be integrated into laser-based training systems to simulate realistic combat scenarios. The filter's ability to handle multiple wavelengths of light makes it ideal for these applications, where accurate simulation and feedback are critical for training effectiveness.

The primary advantage of the present invention lies in its high optical efficiency. The multi-layer anti-reflective coating (160) is carefully engineered to ensure minimal reflection losses and maximize transmission efficiency for the target wavelengths. This enhancement ensures that the filter performs at optimal levels, providing the precise control over the transmission and reflection of light necessary for high-performance laser systems. The specific design of the coating layers, including the alternating use of silicon dioxide (SiO₂) and titanium dioxide (TiO₂), guarantees excellent optical efficiency, allowing the system to function reliably across a variety of wavelengths.

Another major advantage of the invention is its durability and reliability. The inclusion of aluminum oxide (Al₂O₃) in the coating layer provides an additional protective barrier, enhancing the filter’s resistance to environmental factors such as moisture, dust, and chemicals. This makes the filter system well-suited for use in harsh environments, including military training simulators and medical diagnostic systems, where long-term performance and reliability are critical.

The precision and quality control in the manufacturing process are also significant advantages. The invention employs advanced deposition techniques, such as Ion Beam Sputtering (IBS), Electron Beam Evaporation (EBE), and Plasma Enhanced Chemical Vapor Deposition (PECVD), to ensure that each layer is deposited with high accuracy. Additionally, the manufacturing process incorporates stringent quality control measures, guaranteeing that the filter’s optical properties meet the desired specifications. This ensures that the final product delivers consistent and high-quality performance over time.

Moreover, the system is designed with a compact and scalable design. This modular structure allows for easy integration into various systems and can be adapted for use in both small-scale applications, such as handheld devices or compact laser systems, as well as large-scale systems, including training simulators or industrial applications. Its scalability makes it versatile and ideal for a wide range of environments and use cases.

The cost-effective production process further enhances the attractiveness of this invention. By optimizing the manufacturing techniques, the system can be produced at scale without compromising its quality. This cost-efficiency makes it a viable option for large-scale production and broad adoption in industries that require high-performance optical filters, such as defense, healthcare, and environmental monitoring.

Lastly, the invention’s versatility in applications sets it apart from existing technologies. The long pass filter system can be easily adapted for various optical systems, providing precise wavelength discrimination, which is crucial in many industrial, military, and healthcare applications. The versatility of this filter allows it to be employed in a wide range of optical systems, including those used for laser communications, imaging, spectroscopy, and more.

The long pass filter system has a wide array of applications, particularly in fields where precision, durability, and efficiency in optical performance are paramount. One of the most significant areas of application is in military training simulators. The system enables the merging of visible and infrared laser beams, allowing for realistic target engagement simulations in training environments. This is essential for military personnel to practice combat scenarios without the risks and costs associated with live-fire exercises. The filter ensures that both visible and IR laser beams are combined accurately, which is crucial for the success of training systems that aim to simulate real-world combat conditions. The system’s ability to deliver precise and consistent performance across different wavelengths enhances the realism of the simulation, making it a valuable tool for military training.

In medical imaging, the long pass filter system also finds extensive use. Many medical diagnostic devices, such as endoscopes and laser-based imaging devices, rely on precise wavelength discrimination to produce clear, high-quality images. The long pass filter helps by allowing certain wavelengths of light to pass through while blocking others, improving image clarity and providing detailed diagnostics. Whether it is used in non-invasive diagnostic tools or in surgical settings, the system’s ability to enhance the spectral performance of medical imaging devices is a significant advantage, especially for applications requiring precise control over light transmission and reflection.

The filter system is also highly beneficial for use in optical instruments used in fields like spectroscopy, remote sensing, and optical communications. In spectroscopy, for instance, precise wavelength filtering is necessary to ensure accurate measurements of chemical compositions or other material properties. In remote sensing, the long pass filter system can be used to differentiate between various wavelengths of light, which is critical for tasks such as environmental monitoring or detecting pollutants. Similarly, in optical communications, the system can ensure that only specific wavelengths are transmitted or received, improving the accuracy and efficiency of communication links.

Laser communications is another area where the long pass filter system plays a crucial role. In optical communication systems, multiple laser beams are often used to transmit data over long distances. The filter enables the efficient combination of visible and infrared laser beams into a single coherent beam, enhancing the overall performance and reliability of the system. This capability is particularly useful in high-speed communication networks, where precise control over the light waves is required for efficient data transfer.

Finally, the system is ideal for environmental monitoring, where it can be used in laser-based devices to detect pollutants or monitor atmospheric conditions. Environmental monitoring systems require high-precision optical filters to isolate specific wavelengths of light, allowing for accurate data collection. The long pass filter system provides the necessary wavelength discrimination, ensuring that the data collected is both accurate and reliable. Whether used to measure air quality, track climate change, or monitor other environmental factors, the filter system’s ability to transmit and reflect light at precise wavelengths makes it an indispensable tool in this field.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, the detailed description and specific examples, while indicating preferred embodiments of the invention, will be given by way of illustration along with complete specification.

Brief Description of the Drawings

The invention will be further understood from the following detailed description of a preferred embodiment taken in conjunction with an appended drawing, in which:

Fig. 1 illustrates a long pass filter system for integrated laser unit with merged visible and infrared beams in accordance with the exemplary embodiment of the present invention.

Fig. 2 illustrates a method disclosing a long pass filter for integrated laser unit with merged visible and infrared beams in accordance with the exemplary embodiment of the present invention.

It is appreciated that not all aspects and structures of the present invention are visible in a single drawing, and as such multiple views of the invention are presented so as to clearly show the structures of the invention.

Detailed Description of the Invention

The present invention relates to a long pass filter system designed for an integrated laser unit (ILU) that merges visible and infrared (IR) laser beams. The system is engineered to provide high optical efficiency, durability, and precise wavelength discrimination, enabling it to be used in a wide range of applications including military training simulators, medical imaging systems, optical instruments, laser communications, and environmental monitoring. The invention is particularly beneficial in systems where the accurate combination of visible and infrared light is required to deliver superior performance.

According to an exemplary embodiment of the present invention, the long pass filter system comprises a substrate made from BK7 glass or fused silica. These materials were chosen for their high optical clarity and durability, making them ideal for use in optical systems requiring both precision and resistance to environmental stress. The substrate serves as the foundation on which the multi-layer anti-reflective coating is applied.

The coating consists of multiple layers of materials that work together to optimize the performance of the filter. The silicon dioxide (SiO₂) layer provides a low refractive index and contributes to the durability and stability of the filter. The titanium dioxide (TiO₂) layer, with its high refractive index, significantly increases the reflectivity at the wavelength of approximately 625 nm, ensuring that visible light is efficiently reflected by the filter. Aluminum oxide (Al₂O₃), placed as the outermost layer, provides enhanced chemical resistance and mechanical robustness, ensuring that the filter is resistant to environmental factors such as moisture, dust, and temperature fluctuations.

This multi-layer design is crucial for ensuring that the filter achieves the desired spectral performance. The system is characterized by the ability to reflect incident light at approximately 625 nm and transmit light at approximately 930 nm, as outlined in the claims. This wavelength discrimination allows for the seamless integration of visible and infrared beams, which is particularly important for applications such as military training simulators, where both types of laser beams need to be accurately merged and directed for target engagement simulations.

In accordance with an exemplary embodiment of the present invention, the multi-layer coating is specifically engineered to minimize reflection losses and maximize transmission efficiency for the target wavelengths. Present invention further details that the layering arrangement is designed to create constructive interference at the reflection wavelength (approximately 625 nm). This arrangement is crucial for ensuring the filter’s optical efficiency. The SiO₂ and TiO₂ layers alternate to form a stack that enhances the reflection at the target wavelength. The thickness of each layer is critical to the performance of the filter and is optimized to ensure maximum reflectivity at 625 nm while allowing transmission at 930 nm.

The thickness of the layers is controlled precisely to achieve the desired optical characteristics. As specified in the present invention, the thickness of the silicon dioxide (SiO₂) layers in the coating is in the range of 100 nm to 200 nm, and the titanium dioxide (TiO₂) layers are in the range of 30 nm to 50 nm. These thickness ranges are designed to achieve optimal reflectivity and transmissivity characteristics, ensuring that the filter performs well in both reflecting visible light and transmitting infrared light. The system's coating is thus capable of maintaining high efficiency even under varying operating conditions, which is essential for applications in environments where consistent performance is critical.

The aluminum oxide (Al₂O₃) layer, added in the coating, serves a dual purpose. Not only does it improve the durability of the filter by providing chemical and mechanical resistance, but it also contributes to the overall optical efficiency by enhancing the reflectivity at the desired wavelengths. This layer is crucial in ensuring that the filter can withstand the wear and tear of continuous operation, especially in demanding environments like military simulators or medical diagnostic systems.

In accordance with an exemplary embodiment of the present invention, the manufacturing method of the long pass filter system is equally important for ensuring the precise performance described in the claims. As outlined in the present invention, the manufacturing process involves the selection of a high-quality substrate, such as BK7 glass or fused silica, and the deposition of the multi-layer anti-reflective coating on one surface of the substrate. The deposition is carried out using techniques such as Ion Beam Sputtering (IBS), Electron Beam Evaporation (EBE), or Plasma Enhanced Chemical Vapor Deposition (PECVD), which allow for the precise control of the coating layer thickness and uniformity.

The deposition process ensures that each layer of the coating is applied with high accuracy, adhering to the required specifications for reflectivity and transmissivity. The deposition techniques are chosen for their ability to create consistent, high-quality layers that maintain the optical performance of the system. Once the coating is applied, the long pass filter undergoes a quality control process, to measure its optical properties, ensuring that the reflectivity at 625 nm and transmission at 930 nm meet the desired criteria.

After the quality control process, the filter is subjected to a final inspection to ensure that it meets all the specifications required for the system’s intended applications. The manufacturing method guarantees that the long pass filter system can be produced efficiently, with high consistency and quality, making it suitable for mass production and integration into laser-based systems used in military, medical, and industrial applications.

In accordance with another exemplary embodiment of the present invention, the long pass filter system is designed to be integrated into various systems that require precise wavelength control and beam merging. In laser systems, the filter enables the merging of visible and infrared laser beams, providing a high-precision output that is crucial for applications such as target engagement simulations and real-time laser communications. The ability to combine visible and infrared light into a single, coherent beam is essential in systems used for military training simulators, where both visible and IR lasers are used to simulate real-world combat situations. The system's precise wavelength discrimination allows for more accurate simulations of laser-based targeting, improving the training experience for military personnel.

As specified, the filter is also adaptable for use in medical diagnostic systems, particularly in medical imaging, where the precise wavelength filtering is needed to enhance image quality and enable detailed diagnostics. The ability to transmit infrared light while reflecting visible light makes the system ideal for use in laser-based medical imaging systems, such as those used in endoscopy or optical coherence tomography, where high resolution and contrast are required.

In imaging systems, the long pass filter system plays a crucial role in enhancing the spectral performance of the system. Whether in environmental monitoring, spectroscopy, or remote sensing, the filter’s ability to control the transmission and reflection of specific wavelengths ensures that the system can isolate the light needed for accurate measurements. This makes the system an excellent choice for applications in optical instruments used for detecting pollutants, studying atmospheric conditions, or performing detailed chemical analysis.

In accordance with another exemplary embodiment of the present invention, the long pass filter system is also ideal for applications in environmental monitoring, where it can be used in laser-based detection systems. These systems often require high precision in wavelength discrimination to isolate the light reflected or transmitted by specific substances in the environment. The long pass filter allows for accurate measurements of pollutants, atmospheric particles, or other substances, making it a valuable tool in the field of environmental science.

In laser communications, the system’s ability to efficiently combine visible and infrared laser beams into a single output improves the performance and reliability of the communication system. The filter’s high optical efficiency and low loss make it suitable for high-speed communication systems, where maintaining a stable, coherent beam is critical for long-distance data transfer.

Noe referring to figures,
Fig. 1 illustrates the long pass filter system (100) for an integrated laser unit (ILU) with merged visible and infrared beams in accordance with the exemplary embodiment of the present invention. The substrate (150), made from BK7 glass or fused silica, is the foundational material that supports the multi-layer anti-reflective coating (160). These materials are selected for their optical clarity and mechanical strength, ensuring the filter’s long-term stability and performance in demanding environments.

The multi-layer anti-reflective coating (160) consists of alternating layers of silicon dioxide (SiO₂), titanium dioxide (TiO₂), and aluminum oxide (Al₂O₃), as shown in Fig. 1. The SiO₂ layer, being of low refractive index, provides durability, while the TiO₂ layer, with a high refractive index, increases reflectivity at the target wavelength of approximately 625 nm. The Al₂O₃ layer, placed on top, enhances the filter’s resistance to environmental factors, including moisture, dust, and chemical exposure.

The filter system is specifically engineered to reflect light at approximately 625 nm (visible light) and transmit light at approximately 930 nm (infrared light). This precise wavelength discrimination ensures that the filter efficiently merges the visible and infrared laser beams, allowing the integrated laser unit to combine both beams into a single, coherent output for various applications, including target engagement in military simulators and precise diagnostic imaging in medical systems.

Fig. 2 illustrates the method of manufacturing the long pass filter system (100) for an integrated laser unit with merged visible and infrared beams, in accordance with the exemplary embodiment of the present invention. The method begins with the selection of the substrate (150), which is typically made of BK7 glass or fused silica, as indicated in the figure. The substrate must possess high optical clarity to allow light to pass through without distortion while also being mechanically strong to support the layers of coating applied during manufacturing.

Following the substrate selection, the multi-layer anti-reflective coating (160) is applied using advanced deposition techniques such as Ion Beam Sputtering (IBS), Electron Beam Evaporation (EBE), or Plasma Enhanced Chemical Vapor Deposition (PECVD). These techniques ensure that each layer is deposited with high precision. The SiO₂ layer, TiO₂ layer, and Al₂O₃ layer are carefully controlled in thickness to ensure the filter achieves the desired reflection and transmission properties. The layers are deposited in a manner that ensures minimal reflection loss and maximized transmission efficiency for the target wavelengths of 625 nm and 930 nm.

After the deposition process, the long pass filter (140) undergoes a quality control process. The optical properties, including reflectivity and transmissivity, are carefully tested to ensure the filter meets the specified criteria (greater than 90% reflection at 625 nm and greater than 85% transmission at 930 nm). Once the filter passes this rigorous testing, it is subjected to a final inspection to confirm its overall performance and suitability for integration into optical systems.

The protective surface coating is then applied to further enhance the filter’s anti-reflective properties and ensure durability. This protective layer improves the filter's resistance to environmental factors, ensuring reliable operation in various applications.

The long pass filter system (100) is designed to provide significant advantages in various applications due to its high optical efficiency, durability, precision, and versatility. In particular, the multi-layer anti-reflective coating (160) ensures that the system performs optimally in both military training simulators and medical imaging systems, among other fields. By precisely controlling the reflection and transmission at specific wavelengths, the system allows for more accurate simulations and diagnostics, ensuring superior performance in complex optical environments.

The system allows the integration of both visible and infrared laser beams, enabling more realistic training simulations. Military personnel can engage in simulated target practices where both types of laser beams are accurately combined, providing real-time feedback and enhancing the training experience.

The filter’s ability to transmit infrared light and reflect visible light makes it ideal for use in medical diagnostic tools, such as endoscopes and optical coherence tomography (OCT) devices. These systems require precise wavelength control to produce high-quality images for accurate diagnosis.

In optical communication systems, the long pass filter system can combine multiple laser beams into a single coherent beam. This enhances the communication link’s reliability and performance, allowing data to be transmitted efficiently across optical networks.

The system can be used in environmental monitoring devices that employ laser-based technology to detect pollutants or measure atmospheric conditions. The filter’s precision ensures that only the specific wavelengths of light are transmitted or reflected, which is essential for accurate environmental data collection.

In total, the long pass filter system (100) of the present invention offers a robust and efficient solution for merging visible and infrared laser beams in integrated laser units. The system is characterized by its multi-layer anti-reflective coating (160), which ensures high optical efficiency, durability, and wavelength discrimination, enabling it to perform effectively across various applications, including military training, medical imaging, laser communications, and environmental monitoring.

When applying coating to long pass filter, thermal stability, laser damage threshold, coating uniformity and substrate materials are essential to consider. And it is also advisable to consult with a reputable optical manufacturer or coating specialist to refine the design.

Layer thickness calculations:
To calculate layer thickness, we use the Optical Thickness Equation
n X d = (m X λ) / 4
Where n = refractive index
d = physical thickness
m = integer (0, 1, 2 ...)
λ = wavelength
For each layer, we aim to achieve a specific optical thickness (n X d) to control reflections and transmissions.

The method (200) involves two types of coating such as anti-reflective coating and reflective coating and is as follows:
a) Anti-Reflective Coating (930nm):
1. SiO2 (n = 1.45):
- Optical thickness: 1.45 × 120nm = 174nm ≈ (1 × 930nm) / 4
- Physical thickness: 120nm
2. TiO2 (n = 2.3):
- Optical thickness: 2.3 × 40nm = 92nm ≈ (0.5 × 930nm) / 4
- Physical thickness: 40nm
b) Reflective Coating (625nm reflection, 930nm transmission):
1. SiO2 (n = 1.45):
- Optical thickness: 1.45 × 200nm = 290nm ≈ (1 × 625nm) / 2
- Physical thickness: 200nm
2. TiO2 (n = 2.3):
- Optical thickness: 2.3 × 100nm = 230nm ≈ (1 × 625nm) / 2
- Physical thickness: 100nm
3. Al2O3 (n = 1.65):
- Optical thickness: 1.65 × 50nm = 82.5nm ≈ (0.5 × 625nm) / 2
- Physical thickness: 50nm
c) Repeat reflective coating steps 1, 2 & 3 for 5-7 layers to get high reflectivity and transmission.

While doing coating design calculations, below are the key points to consider:
1. Refractive index: Material properties affect optical thickness.
2. Wavelength: Coating design is specific to 625nm and 930nm.
3. Layer count: More layers increase reflectivity but also increase coating complexity.
4. Thickness tolerance: ±5-10% tolerance affects coating performance.
In accordance with the exemplary embodiment of the present invention a method (200) is provided to ensure proper reflection of both laser and IR beams are accurately directed along the alignment and simulation axes for precise targeting.

The described exemplary embodiments are to be considered in all respects only as illustrative and not restrictive. Variations in the arrangement of the structure are possible falling within the scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.
, Claims:5. CLAIMS
We claim
1. A long pass filter system (100) for an integrated laser unit, comprising:
a substrate (150) made of a material selected from the group consisting of BK7 glass and fused silica, providing high optical clarity and durability; and
a multi-layer anti-reflective coating (160) applied to one surface of the substrate (150), wherein the coating consists of:
at least one layer of silicon dioxide (SiO₂), exhibiting low refractive index properties and enhancing the overall durability of the filter;
at least one layer of titanium dioxide (TiO₂), providing a high refractive index that significantly increases reflectivity at predetermined wavelengths; and
at least one layer of aluminum oxide (Al₂O₃), improving the chemical resistance and mechanical robustness of the filter;
Characterized by,
the multi-layer anti-reflective coating (160) being specifically plotted to reflect incident light at a wavelength of approximately 625 nm and to transmit light at a wavelength of approximately 930 nm, thereby achieving desired spectral performance, with the coating thickness optimized to minimize reflection losses and maximize transmission efficiency for the target wavelengths;
the layering arrangement is configured such that alternating layers of SiO₂ and TiO₂ create constructive interference at the reflection wavelength (625 nm), thereby enhancing the filter's optical efficiency and suitability for integration into laser systems, imaging systems, or other optical instruments requiring precise wavelength discrimination.

2. The long pass filter system (100) of claim 1, wherein the substrate (150) is represented by a thickness optimized to minimize weight while maintaining structural integrity and optical performance, ensuring durability and reducing the overall weight of the system.

3. The long pass filter system (100) of claim 1, wherein the thickness of the silicon dioxide (SiO₂) layers in the coating (160) is in the range of 100 nm to 200 nm, and the thickness of the titanium dioxide (TiO₂) layers is in the range of 30 nm to 50 nm, achieving optimal reflectivity and transmissivity characteristics.

4. The long pass filter system (100) of claim 1, wherein the aluminum oxide (Al₂O₃) layer in the coating (160) serves as a protective barrier, enhancing the filter's durability against environmental factors such as moisture, dust, and chemical exposure.

5. The long pass filter system (100) of claim 1, wherein the optical performance of the filter is characterized by a reflection coefficient greater than 90% at approximately 625 nm and a transmission coefficient greater than 85% at approximately 930 nm, ensuring effective filtering capabilities.

6. The long pass filter system (100) of claim 1, wherein the filter (140) is treated with a surface coating to further enhance its anti-reflective properties, resulting in a reduction of surface reflections and improved light transmission.

7. The long pass filter system (100) of claim 1, wherein the configuration of the layers in the coating (160) is designed to provide specific angular performance, allowing the filter (140) to maintain its optical characteristics across a range of incident angles, ensuring consistent performance under varying alignment conditions.

8. The long pass filter system (100) of claim 1, wherein the system (100) is characterized by the multi-layer coating (160) being optimized for laser systems, imaging systems, and optical instruments requiring precise wavelength discrimination, where the precise alignment of light at specific wavelengths is critical for operational efficiency.

9. The long pass filter system (100) of claim 1, wherein the filter (140) is suitable for integration in training simulators, military applications, medical diagnostic systems, or other optical instruments requiring high precision filtering.

10. A method of manufacturing the long pass filter system (100) as claimed in claim 1, comprising the steps of:
selecting a substrate (150) made from either BK7 glass or fused silica, ensuring high optical clarity and durability;
depositing a multi-layer anti-reflective coating (160) on one surface of the substrate (150), the coating consisting of at least one layer of silicon dioxide (SiO₂), at least one layer of titanium dioxide (TiO₂), and at least one layer of aluminum oxide (Al₂O₃), using a deposition technique selected from Ion Beam Sputtering (IBS), Electron Beam Evaporation (EBE), or Plasma Enhanced Chemical Vapor Deposition (PECVD), wherein the deposition process includes precise control of the layer thickness to achieve desired optical properties;
ensuring that the multi-layer coating (160) reflects light at approximately 625 nm and transmits light at approximately 930 nm, with the coating thickness optimized to minimize reflection losses and maximize transmission efficiency for the target wavelengths;
subjecting the long pass filter (140) to a quality control process to measure its optical properties, ensuring that the reflectivity and transmissivity specifications are met before final assembly and use;
applying a protective surface coating to enhance the anti-reflective properties and ensure durability against environmental factors such as moisture, dust, and chemical exposure;
conducting final inspection of the filter's optical performance, ensuring the reflection coefficient at approximately 625 nm exceeds 90%, and the transmission coefficient at approximately 930 nm exceeds 85%, verifying the long pass filter’s suitability for use in integrated laser systems, imaging systems, and other optical instruments requiring precise wavelength discrimination.

6. DATE AND SIGNATURE

Dated this 28th November 2024
Signature

Mr. Srinivas Maddipati
IN/PA 3124
Agent for Applicant