> Quick answer: HDPE and polycarbonate lenses do not significantly differ in detection accuracy under fog or snow, according to the available research [1][25]. Design features like active heating mechanisms are more critical than material choice for maintaining performance in harsh conditions.
Understanding PIR Sensor Lens Materials: HDPE vs. Polycarbonate
When it comes to solar lamps and motion sensors in Romania’s varying weather conditions, understanding the impact of lens materials on detection accuracy is crucial. This article delves into how high-density polyethylene (HDPE) and Fresnel polycarbonate lenses perform under fog or snow. We explore their optical properties, environmental robustness, and design considerations.
Key Optical Properties
The primary distinction between HDPE and polycarbonate lies in their optical and thermal properties [1][25]. HDPE is noted for its excellent physical reception of infrared (IR) rays and clear IR ray receptivity, avoiding shadow effects behind the light diffuser [1]. Polycarbonate, on the other hand, is known for its UV stability and availability in flame-retardant forms [13], making it a common choice for lighting applications.
Both materials are transparent to both IR and visible light, ensuring they do not block LED illumination [23][18]. However, no direct comparison of their performance under fog or snow conditions is provided by the sources [1].
Environmental Interference
Fog and snow can significantly interfere with sensor performance. Particulates like dust, rain, and condensation can obscure a sensor’s field of view, leading to false alarms [3][6][12]. Dew and frost reduce transmittance and introduce spectral distortion in solar radiation sensors by up to 30-40% [12], indicating moisture on the lens surface may obstruct infrared signals regardless of material.
Active heating mechanisms can mitigate these effects. Heated lenses, made from materials like polycarbonate or glass, are designed to eliminate condensation and ice buildup [25]. While HDPE is not specifically discussed in this context, its performance under similar conditions remains unclear [1].
Design Considerations
The design of the Fresnel lens itself plays a crucial role. Integrated light diffusers behind which PIR sensors are located help minimize shadow effects caused by the sensor body and improve detection capacity [4][10]. HDPE’s penetrability to both IR and LED light makes it suitable for this dual role [23].
Temperature differentials also affect performance, with Panasonic’s PIR sensors requiring at least a 4°C difference between human bodies and the environment for reliable motion detection [20]. In cold climates where ambient temperatures are low, thermal contrast is minimal, impacting accuracy [6]. However, no comparative data on how HDPE or polycarbonate lenses perform under such conditions is provided.
Long-Term Environmental Degradation
Polycarbonate is known for its UV resistance when stabilized with additives like HALS (Hindered Amine Light Stabilizers) or fluoropolymers [18]. While HDPE is also used in outdoor applications due to durability, no comparative data on long-term optical clarity under repeated exposure to moisture, freezing, or UV radiation is available [1][23].
Conclusion
The chosen lens material (HDPE vs. polycarbonate) does not significantly impact detection accuracy in fog or snow, as per the research [1][25]. Design features such as lens separation from the sensor and active anti-fogging/heating mechanisms are more critical than the choice of material.
Key Takeaways
- HDPE performs well for IR reception and avoids shadow effects behind diffusers.
- Polycarbonate is UV stable and used in lighting applications, but no direct comparison with HDPE under fog/snow exists.
- Active heating mechanisms can mitigate fogging and ice buildup more effectively than lens material choice.
Frequently Asked Questions
[{„q”: „What makes HDPE suitable for IR reception?”, „a”: „HDPE is excellent at receiving infrared rays and avoids shadow effects behind light diffusers, making it ideal for PIR sensors [1].”},
{„q”: „How do fog and snow affect PIR sensor performance?”, „a”: „Fog and snow can obscure the field of view, leading to false alarms and up to 30-40% measurement errors due to spectral distortion [3][6][12].”},
{„q”: „What role does temperature play in PIR detection accuracy?”, „a”: „PIR sensors require at least a 4°C difference between the human body and ambient temperatures for reliable motion detection, particularly challenging in cold climates [20].”}]
References
- [1] US10757787B2_-_LED_security_light_with_integrated_motion_sensor__9db299cf — patent
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intrusion detected by one of a plurality of PIR light bulbs pointing to different directions can trigger all PIR light bulbs to be turned on synchronously. According to the present disclosure, an LED lamp housing accommodating a Fresnel lens, a PIR motion sensor, an LED light emitting unit and a power control circuitry is configured with a two-piece housing construction divided into a first part housing and a second part housing. The first part housing serves both as a light diffuser and as a cover to protect the operating components inside the LED lamp housing. The Fresnel lens is designed to incorporate with the first part housing in two ways. The first way is to build the Fresnel lens in the light diffuser to integrate with the surface of the first part housing to collect IR ray signals generated from an intruder. The second way is to install a separate piece of Fresnel lens positioned behind the first part housing. The Fresnel lens positioned behind the first part housing can be made with a clear IR ray receptive material to avoid any shadow effect, preferably using HDPE (high density polyethylene) which performs an excellent physical reception feature to an infrared ray. Both ways can successfully collect and converge IR ray signals remotely on a focal point in a central space of the second part housing where PIR motion sensor is positioned to receive condensed IR ray signals. The second part housing accommodates all other operating components except the Fresnel lens. Th
- [3] US8232909B2_-_Doppler_radar_motion_detector_for_an_outdoor__bfcc35d2 — patent
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MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE – Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS – Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps – Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection Definitions – the present invention relates to the field of motion detection in an outdoor environment. More specifically, the invention relates to apparatus and methods for using Doppler radar in a motion detection application for an outdoor light fixture. – PIR sensors passive infrared sensors – Traditional motion-sensing products use passive infrared (PIR) sensors to recognize moving heat sources, such as people, animals, or car engines. – PIR sensors have been the standard technology used in outdoor motion-sensing products for years, and the effectiveness of PIR sensors is typically determined by the design of the motion-sensing apparatus, the quality of the components used in making the motion sensing apparatus, and the current weather conditions. Rain, and wind-blown leaves and branches cause false positives, or false tripping, of a typical PIR motion sensor. Further, the typical PIR motion sensor performs differently in heat than it does in cold. Therefore, depending on where a user lives geographically, climate can have an effect on the performance of the PIR motion sensor and accordingly the fixture
- [4] US10757787B2_-_LED_security_light_with_integrated_motion_sensor__9db299cf — patent
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down conventional one-piece structure of the PIR motion sensing unit into two mutually separated and remotely located components without affecting the functional performance of the PIR motion sensor. – the Fresnel lens can be designed to integrate with the light diffuser or can be designed as a separate piece located behind the light diffuser, and on the other hand, the PIR motion sensor can be remotely located at a focal point on which the focused IR ray signals collected by the Fresnel lens are converged and surrounded by the LEDs. With such arrangement, the size and curvature of the Fresnel lens can be enlarged to maximize detection scope and detection distance, and there is no more solid body to block the LED light to cause a shadow problem. This is the technical background of the present disclosure which can release the constraint of Fresnel lens design and also eliminate the shadow problem. – the present disclosure provides a technology to eliminate the drawbacks of the above mentioned two related arts related to a construction of a PIR light bulb. – the application of the present disclosure to a light bulb based construction is only one embodiment of the present disclosure. – the key technology of the present disclosure is the knock down of a traditional PIR motion sensing unit into two separated components, namely, the Fresnel lens and the PIR motion sensor, which do not need to be packaged together as one operating component. – the PIR motion sensor is managed to be
- [6] US8232909B2_-_Doppler_radar_motion_detector_for_an_outdoor__bfcc35d2 — patent
source passage
of motion detection in an outdoor environment. More specifically, the invention relates to apparatus and methods for using Doppler radar in a motion detection application for an outdoor light fixture. Traditional motion-sensing products use passive infrared (PIR) sensors to recognize moving heat sources, such as people, animals, or car engines. PIR sensors have been the standard technology used in outdoor motion-sensing products for years, and the effectiveness of PIR sensors is typically determined by the design of the motion-sensing apparatus, the quality of the components used in making the motion sensing apparatus, and the current weather conditions. Rain, and wind-blown leaves and branches cause false positives, or false tripping, of a typical PIR motion sensor. Further, the typical PIR motion sensor performs differently in heat than it does in cold. Therefore, depending on where a user lives geographically, climate can have an effect on the performance of the PIR motion sensor and accordingly the fixture. In cold climates people are generally wearing insulated coats. The outer surface of the coat can be a similar temperature to the surrounding environment, thereby making it difficult to detect a person's motion. On the other hand, in warm climates, a person body temperature while walking across a paved driveway may be the same temperature or substantially close to the same temperature as the pavement, thereby making it difficult for the PIR sensors to detect motion. Ano
- [10] US10757787B2_-_LED_security_light_with_integrated_motion_sensor__9db299cf — patent
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shadow problem. This is the technical background of the present disclosure which can release the constraint of Fresnel lens design and also eliminate the shadow problem. In response to the above-referenced technical inadequacies, the present disclosure provides a technology to eliminate the drawbacks of the above mentioned two related arts related to a construction of a PIR light bulb. The application of the present disclosure to a light bulb based construction is only one embodiment of the present disclosure. Regardless applications in any PIR based lighting devices, the key technology of the present disclosure is the knock down of a traditional PIR motion sensing unit into two separated components, namely, the Fresnel lens and the PIR motion sensor, which do not need to be packaged together as one operating component. The PIR motion sensor is managed to be surrounded by the LEDs of an LED light emitting unit and is located at a focal point where the IR ray signals collected by the Fresnel lens are converged and focused on. The Fresnel lens is either integrated with a light diffuser to become a part of the light diffuser or a separate piece located right behind the light diffuser to perform IR ray signal collecting function. The Fresnel lens, the PIR motion sensor, the LEDs and a power control unit are all accommodated in a lamp housing to become a compact design. The PIR light bulb is designed with a screw-in lamp cap for directly adapting to an AC power source to perform a
- [12] Solar_Radiation_How_Dew_Frost_and_Soiling_Affect__2eb0e733 — authority
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# Solar Radiation: How Dew, Frost, and Soiling Affect Irradiance Monitoring, and Ways to Mitigate – Kipp & Zonen Blog Source: Blog/Web URL: https://www.kippzonen.com/blog/solar-radiation-soiling-dew-frost-pyranometers Author: Blog Team Date: 2025-06-10 Don’t Let Dew, Frost, or Dirt Cloud Your Data Accurate measurement of solar radiation is essential for applications ranging from climate modeling and atmospheric research to solar energy forecasting. Yet, one of the most underestimated sources of error in a site’s ability to capture accurate irradiance measurements is due to contamination of your sensor’s dome. Dew, frost, and soiling are the main environmental factors that can significantly degrade the optical clarity of a pyranometer’s dome. Dew and frost typically form due to radiative cooling during clear nights, while dust and dirt accumulate gradually over time. These seemingly minor surface changes can reduce transmittance and introduce spectral distortion, leading to measurement errors of up to 30–40%, a serious threat to data accuracy. In the webinar embedded below, we explore the physics behind these environmental interferences and how they compromise the performance of solar radiation sensors. We also discuss practical strategies to mitigate these effects and ensure high-quality data. Here’s what you’ll learn: 🔬 Why dome cleanliness is critical: Even microscopic layers of moisture or dust can alter the spectral response of a pyranometer, skewing your solar radiation
- [13] Tertiary_optics_deliver_benefits_in_SSL_product_design_Buildings__15b21c39 — authority
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# Tertiary optics deliver benefits in SSL product design (MAGAZINE) Source: Blog/Web URL: https://www.buildings.com/architecture/interiors/article/55255142/tertiary-optics-deliver-benefits-in-ssl-product-design-magazine Author: Date: 2014-03-11 Polycarbonate is the preferred plastic of choice for lighting applications. It’s available in UV-stable versions for outdoor applications and in UL-listed versions to meet flammability requirements that are typically dictated by the class of the LED driver. Holographic versus volumetric diffusion There are also different approaches to tertiary optics that must meet application requirements. Tertiary optics are available in low- and high-performance versions. The main difference lies in the diffusion mechanism. High-performance holographic diffusers incorporate a sub-micron surface relief pattern on top of a very clear substrate. Through a combination of diffraction and refraction, the diffusion (which occurs only on the surface of the substrate) is extremely efficient (up to 92%) — independent of thickness — and provides precise angular beam control. Lower-performance diffusers, such as volumetric diffusers, incorporate scattering elements within the volume of the substrate. These diffusers typically are less efficient in the 30–70% transmission range. The optical properties of volumetric diffusers are very dependent on thickness and provide little or no control of the beam angle of a lamp or fixture. Optical modeling One of the most v
- [18] US9433336B2_-_Self-cleaning_solar_panels_and_-_Google_Patents__22b92a64 — patent
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that of the mirror. Most Fresnel lenses are made of polymer material. The step-wise convex side of the planoconvex lens is at the back side while the solar radiation is incident on the front plane side. 10. Minimization of UV Radiation Related Damage to the EDS and Improving Durability in Outdoor Applications (a) Stabilizers, blockers, and absorbers are often used to promote UV resistance. However, the modifications should not compromise the transparency of the plastic in the visible spectrum. The stabilizers react with UV radiation. One of the common stabilizers is called HALS (Hindered Amine Light Stabilizer). These molecules absorb the excited groups and prevent the chemical reaction of the radicals. Fluoropolymer has good UV resistance because of its strong carbon-fluorine (C—F) bond. Fluoropolymer resin (such as marketed by DuPont as Tefzel) has transparency over 94% in the visible range. Polyurethane (PU) and silicone have good UV resistance. (b) The best UV resistant polymers are the imides, polyimide (PEI) has been used for space applications. Fluorescent whitening agents (FWA) can be added to the polymer. The FWA molecules can absorb UV photons and undergo fluorescent radiation in the visible range providing additional radiation energy to the solar cells for energy conversion. Application of UV stabilizers helps in lowering the temperature of the crystalline solar cells by absorbing high energy photons and radiating part of the energy in the visible radiation. 11. Ad
- [20] Panasonics_PIR_Motion_Sensors_Panasonic_Industrial_Devices__ecf8d667 — authority
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amplifying the minute electrical signals. How did you manage to bring together so many components in such a restricted space? We used something called insert moulding technology, a moulding technique that binds metal and plastic. The components are placed into a metal mould, and the metal mould is then filled with plastic to form a moulded article in which the metal and plastic have become one. Insert moulding combines substances with different properties and thus requires precise accuracy, and close attention must be paid to thermal expansion and thermal conductivity. Do the sensors ever fail to detect the minimal amounts of infrared radiation emitted from the body? The main reason for failed detections is when there is little difference in temperature between the body and its surroundings. With PaPIRs, we guarantee detection so long as there is 4°C or more difference between the body and its surrounding environment. Regardless of the season, as long as there is a difference of 4°C or more, PaPIRs can detect the infrared radiation. Insert moulding requires high accuracy. Processing accuracy is checked on each sensor using an electron microscope. PaPIRs quickly respond to market needs and continue to evolve. Production volume of PaPIRs increased around 2017—Was there a turning point? I think it was down to the spread of IoT. We originally thought that lighting control would be the target market for PaPIRs, but with the recent spread of IoT, demand for other applications has g
- [23] US10757787B2_-_LED_security_light_with_integrated_motion_sensor__9db299cf — patent
source passage
circuit boards. – a heat sink is also attached to the circuit board of the LED module for dissipating heat generated by the LED module of the light emitting unit 65 . – the PIR motion sensor 15 B is additionally wrapped with a heat insulating material such that an IR ray signal detection circuitry electrically connected with the PIR motion sensor 15 B can operate in an environment with a stable temperature. – the power control unit (not shown) is installed in a control box 85 behind the second part housing 25 B and is electrically connected to the LED module of the light emitting unit 65 for controlling a transmission of electric power delivered to the LED module of the light emitting unit 65 . – the first part housing 25 A and the second part housing 25 B are fastened together through a fastening mechanism, wherein the fastening mechanism can be an adhesive, a press to lock device, a plurality of screws or any other fastening device. – the Fresnel lens 15 A is made with a material which is both IR ray and LED light receptive and penetrable such that the LED light is not blocked by the Fresnel lens 15 A. – the shape of the Fresnel lens 15 A can be designed in different patterns as needed for maximizing a detection function. – the signal processing circuitry when the PIR motion sensor 15 B operating with the signal processing circuitry determines that the IR ray signals collected by the Fresnel lens 15 A represent a motion intrusion, the signal processing circuitry consequentl
- [25] US9629220B2_-_Sensor-based_controllable_LED_lighting_system__333bafbd — patent
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condensation or fogging when activated by the Thermal Management Circuit. – the optional wired lenses or optional wired light diffusers would have a wire embedded within the lens or diffuser that would heat up to melt ice or to eliminate condensation or fog. – the wired lens or the wired light diffusers may be tinted to provide different shades of polycarbonate, glass, acrylic, or other transparent or semi-transparent materials to serve better for particular applications such as fog, underwater purposes, or to serve other applications. – the wired lenses or wired light diffusers can be made out of bullet resistant or standard strength materials. – One or more lens or non-lens filters and/or light diffusers are included in the fixture to seal the unit with a transparent or semi-transparent cover to allow the transfer of light out through the light fixture while protecting internal components. – the lens filters or light diffusers may be tinted to allow the desired lighting effect for fog or other considerations for different applications. – the lens filters or light diffusers may be tinted to allow the desired lighting effect for fog or other considerations for different applications. – the lens filters or the light diffusers may be constructed with different shades of polycarbonate, glass, acrylic, or other transparent or semi-transparent materials to serve better for particular applications such as fog, underwater purposes, or to serve other applications. – the lens filters
intrusion detected by one of a plurality of PIR light bulbs pointing to different directions can trigger all PIR light bulbs to be turned on synchronously. According to the present disclosure, an LED lamp housing accommodating a Fresnel lens, a PIR motion sensor, an LED light emitting unit and a power control circuitry is configured with a two-piece housing construction divided into a first part housing and a second part housing. The first part housing serves both as a light diffuser and as a cover to protect the operating components inside the LED lamp housing. The Fresnel lens is designed to incorporate with the first part housing in two ways. The first way is to build the Fresnel lens in the light diffuser to integrate with the surface of the first part housing to collect IR ray signals generated from an intruder. The second way is to install a separate piece of Fresnel lens positioned behind the first part housing. The Fresnel lens positioned behind the first part housing can be made with a clear IR ray receptive material to avoid any shadow effect, preferably using HDPE (high density polyethylene) which performs an excellent physical reception feature to an infrared ray. Both ways can successfully collect and converge IR ray signals remotely on a focal point in a central space of the second part housing where PIR motion sensor is positioned to receive condensed IR ray signals. The second part housing accommodates all other operating components except the Fresnel lens. Th
MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE – Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS – Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps – Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection Definitions – the present invention relates to the field of motion detection in an outdoor environment. More specifically, the invention relates to apparatus and methods for using Doppler radar in a motion detection application for an outdoor light fixture. – PIR sensors passive infrared sensors – Traditional motion-sensing products use passive infrared (PIR) sensors to recognize moving heat sources, such as people, animals, or car engines. – PIR sensors have been the standard technology used in outdoor motion-sensing products for years, and the effectiveness of PIR sensors is typically determined by the design of the motion-sensing apparatus, the quality of the components used in making the motion sensing apparatus, and the current weather conditions. Rain, and wind-blown leaves and branches cause false positives, or false tripping, of a typical PIR motion sensor. Further, the typical PIR motion sensor performs differently in heat than it does in cold. Therefore, depending on where a user lives geographically, climate can have an effect on the performance of the PIR motion sensor and accordingly the fixture
down conventional one-piece structure of the PIR motion sensing unit into two mutually separated and remotely located components without affecting the functional performance of the PIR motion sensor. – the Fresnel lens can be designed to integrate with the light diffuser or can be designed as a separate piece located behind the light diffuser, and on the other hand, the PIR motion sensor can be remotely located at a focal point on which the focused IR ray signals collected by the Fresnel lens are converged and surrounded by the LEDs. With such arrangement, the size and curvature of the Fresnel lens can be enlarged to maximize detection scope and detection distance, and there is no more solid body to block the LED light to cause a shadow problem. This is the technical background of the present disclosure which can release the constraint of Fresnel lens design and also eliminate the shadow problem. – the present disclosure provides a technology to eliminate the drawbacks of the above mentioned two related arts related to a construction of a PIR light bulb. – the application of the present disclosure to a light bulb based construction is only one embodiment of the present disclosure. – the key technology of the present disclosure is the knock down of a traditional PIR motion sensing unit into two separated components, namely, the Fresnel lens and the PIR motion sensor, which do not need to be packaged together as one operating component. – the PIR motion sensor is managed to be
of motion detection in an outdoor environment. More specifically, the invention relates to apparatus and methods for using Doppler radar in a motion detection application for an outdoor light fixture. Traditional motion-sensing products use passive infrared (PIR) sensors to recognize moving heat sources, such as people, animals, or car engines. PIR sensors have been the standard technology used in outdoor motion-sensing products for years, and the effectiveness of PIR sensors is typically determined by the design of the motion-sensing apparatus, the quality of the components used in making the motion sensing apparatus, and the current weather conditions. Rain, and wind-blown leaves and branches cause false positives, or false tripping, of a typical PIR motion sensor. Further, the typical PIR motion sensor performs differently in heat than it does in cold. Therefore, depending on where a user lives geographically, climate can have an effect on the performance of the PIR motion sensor and accordingly the fixture. In cold climates people are generally wearing insulated coats. The outer surface of the coat can be a similar temperature to the surrounding environment, thereby making it difficult to detect a person's motion. On the other hand, in warm climates, a person body temperature while walking across a paved driveway may be the same temperature or substantially close to the same temperature as the pavement, thereby making it difficult for the PIR sensors to detect motion. Ano
shadow problem. This is the technical background of the present disclosure which can release the constraint of Fresnel lens design and also eliminate the shadow problem. In response to the above-referenced technical inadequacies, the present disclosure provides a technology to eliminate the drawbacks of the above mentioned two related arts related to a construction of a PIR light bulb. The application of the present disclosure to a light bulb based construction is only one embodiment of the present disclosure. Regardless applications in any PIR based lighting devices, the key technology of the present disclosure is the knock down of a traditional PIR motion sensing unit into two separated components, namely, the Fresnel lens and the PIR motion sensor, which do not need to be packaged together as one operating component. The PIR motion sensor is managed to be surrounded by the LEDs of an LED light emitting unit and is located at a focal point where the IR ray signals collected by the Fresnel lens are converged and focused on. The Fresnel lens is either integrated with a light diffuser to become a part of the light diffuser or a separate piece located right behind the light diffuser to perform IR ray signal collecting function. The Fresnel lens, the PIR motion sensor, the LEDs and a power control unit are all accommodated in a lamp housing to become a compact design. The PIR light bulb is designed with a screw-in lamp cap for directly adapting to an AC power source to perform a
# Solar Radiation: How Dew, Frost, and Soiling Affect Irradiance Monitoring, and Ways to Mitigate – Kipp & Zonen Blog Source: Blog/Web URL: https://www.kippzonen.com/blog/solar-radiation-soiling-dew-frost-pyranometers Author: Blog Team Date: 2025-06-10 Don’t Let Dew, Frost, or Dirt Cloud Your Data Accurate measurement of solar radiation is essential for applications ranging from climate modeling and atmospheric research to solar energy forecasting. Yet, one of the most underestimated sources of error in a site’s ability to capture accurate irradiance measurements is due to contamination of your sensor’s dome. Dew, frost, and soiling are the main environmental factors that can significantly degrade the optical clarity of a pyranometer’s dome. Dew and frost typically form due to radiative cooling during clear nights, while dust and dirt accumulate gradually over time. These seemingly minor surface changes can reduce transmittance and introduce spectral distortion, leading to measurement errors of up to 30–40%, a serious threat to data accuracy. In the webinar embedded below, we explore the physics behind these environmental interferences and how they compromise the performance of solar radiation sensors. We also discuss practical strategies to mitigate these effects and ensure high-quality data. Here’s what you’ll learn: 🔬 Why dome cleanliness is critical: Even microscopic layers of moisture or dust can alter the spectral response of a pyranometer, skewing your solar radiation
# Tertiary optics deliver benefits in SSL product design (MAGAZINE) Source: Blog/Web URL: https://www.buildings.com/architecture/interiors/article/55255142/tertiary-optics-deliver-benefits-in-ssl-product-design-magazine Author: Date: 2014-03-11 Polycarbonate is the preferred plastic of choice for lighting applications. It’s available in UV-stable versions for outdoor applications and in UL-listed versions to meet flammability requirements that are typically dictated by the class of the LED driver. Holographic versus volumetric diffusion There are also different approaches to tertiary optics that must meet application requirements. Tertiary optics are available in low- and high-performance versions. The main difference lies in the diffusion mechanism. High-performance holographic diffusers incorporate a sub-micron surface relief pattern on top of a very clear substrate. Through a combination of diffraction and refraction, the diffusion (which occurs only on the surface of the substrate) is extremely efficient (up to 92%) — independent of thickness — and provides precise angular beam control. Lower-performance diffusers, such as volumetric diffusers, incorporate scattering elements within the volume of the substrate. These diffusers typically are less efficient in the 30–70% transmission range. The optical properties of volumetric diffusers are very dependent on thickness and provide little or no control of the beam angle of a lamp or fixture. Optical modeling One of the most v
that of the mirror. Most Fresnel lenses are made of polymer material. The step-wise convex side of the planoconvex lens is at the back side while the solar radiation is incident on the front plane side. 10. Minimization of UV Radiation Related Damage to the EDS and Improving Durability in Outdoor Applications (a) Stabilizers, blockers, and absorbers are often used to promote UV resistance. However, the modifications should not compromise the transparency of the plastic in the visible spectrum. The stabilizers react with UV radiation. One of the common stabilizers is called HALS (Hindered Amine Light Stabilizer). These molecules absorb the excited groups and prevent the chemical reaction of the radicals. Fluoropolymer has good UV resistance because of its strong carbon-fluorine (C—F) bond. Fluoropolymer resin (such as marketed by DuPont as Tefzel) has transparency over 94% in the visible range. Polyurethane (PU) and silicone have good UV resistance. (b) The best UV resistant polymers are the imides, polyimide (PEI) has been used for space applications. Fluorescent whitening agents (FWA) can be added to the polymer. The FWA molecules can absorb UV photons and undergo fluorescent radiation in the visible range providing additional radiation energy to the solar cells for energy conversion. Application of UV stabilizers helps in lowering the temperature of the crystalline solar cells by absorbing high energy photons and radiating part of the energy in the visible radiation. 11. Ad
amplifying the minute electrical signals. How did you manage to bring together so many components in such a restricted space? We used something called insert moulding technology, a moulding technique that binds metal and plastic. The components are placed into a metal mould, and the metal mould is then filled with plastic to form a moulded article in which the metal and plastic have become one. Insert moulding combines substances with different properties and thus requires precise accuracy, and close attention must be paid to thermal expansion and thermal conductivity. Do the sensors ever fail to detect the minimal amounts of infrared radiation emitted from the body? The main reason for failed detections is when there is little difference in temperature between the body and its surroundings. With PaPIRs, we guarantee detection so long as there is 4°C or more difference between the body and its surrounding environment. Regardless of the season, as long as there is a difference of 4°C or more, PaPIRs can detect the infrared radiation. Insert moulding requires high accuracy. Processing accuracy is checked on each sensor using an electron microscope. PaPIRs quickly respond to market needs and continue to evolve. Production volume of PaPIRs increased around 2017—Was there a turning point? I think it was down to the spread of IoT. We originally thought that lighting control would be the target market for PaPIRs, but with the recent spread of IoT, demand for other applications has g
circuit boards. – a heat sink is also attached to the circuit board of the LED module for dissipating heat generated by the LED module of the light emitting unit 65 . – the PIR motion sensor 15 B is additionally wrapped with a heat insulating material such that an IR ray signal detection circuitry electrically connected with the PIR motion sensor 15 B can operate in an environment with a stable temperature. – the power control unit (not shown) is installed in a control box 85 behind the second part housing 25 B and is electrically connected to the LED module of the light emitting unit 65 for controlling a transmission of electric power delivered to the LED module of the light emitting unit 65 . – the first part housing 25 A and the second part housing 25 B are fastened together through a fastening mechanism, wherein the fastening mechanism can be an adhesive, a press to lock device, a plurality of screws or any other fastening device. – the Fresnel lens 15 A is made with a material which is both IR ray and LED light receptive and penetrable such that the LED light is not blocked by the Fresnel lens 15 A. – the shape of the Fresnel lens 15 A can be designed in different patterns as needed for maximizing a detection function. – the signal processing circuitry when the PIR motion sensor 15 B operating with the signal processing circuitry determines that the IR ray signals collected by the Fresnel lens 15 A represent a motion intrusion, the signal processing circuitry consequentl
condensation or fogging when activated by the Thermal Management Circuit. – the optional wired lenses or optional wired light diffusers would have a wire embedded within the lens or diffuser that would heat up to melt ice or to eliminate condensation or fog. – the wired lens or the wired light diffusers may be tinted to provide different shades of polycarbonate, glass, acrylic, or other transparent or semi-transparent materials to serve better for particular applications such as fog, underwater purposes, or to serve other applications. – the wired lenses or wired light diffusers can be made out of bullet resistant or standard strength materials. – One or more lens or non-lens filters and/or light diffusers are included in the fixture to seal the unit with a transparent or semi-transparent cover to allow the transfer of light out through the light fixture while protecting internal components. – the lens filters or light diffusers may be tinted to allow the desired lighting effect for fog or other considerations for different applications. – the lens filters or light diffusers may be tinted to allow the desired lighting effect for fog or other considerations for different applications. – the lens filters or the light diffusers may be constructed with different shades of polycarbonate, glass, acrylic, or other transparent or semi-transparent materials to serve better for particular applications such as fog, underwater purposes, or to serve other applications. – the lens filters