Food preservation method and system based on dynamic spectrum adjustment
The food preservation method using dynamic spectral adjustment utilizes multispectral LED modules and sensors to adjust spectral parameters in real time, solving the problems of lack of active preservation and high energy consumption in lighting for fresh food, and achieving personalized and intelligent preservation effects.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHENZHEN DONGRI LIGHTING CO LTD
- Filing Date
- 2026-01-12
- Publication Date
- 2026-05-05
AI Technical Summary
Current technologies for lighting fresh food mainly focus on color rendering and lack active preservation functions. Ultraviolet germicidal lamps cannot be intelligently adjusted, which may have a negative impact on photosensitive foods and consume a lot of energy.
A food preservation method based on dynamic spectral adjustment is adopted. Through information acquisition, spectral decision-making and dynamic adjustment, a multispectral LED module is used to output a targeted preservation spectrum. Combined with image recognition and environmental sensors, the spectral parameters are adjusted in real time to achieve personalized preservation.
It achieves intelligent preservation based on food type and environmental conditions, significantly extending shelf life, reducing food spoilage, improving preservation effect and reducing energy consumption, and has continuous optimization capabilities.
Smart Images
Figure CN121970796A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of food preservation technology, specifically to a food preservation method and system based on dynamic spectral adjustment. Background Technology
[0002] Dynamic spectral modulation-based food preservation is a novel technology that utilizes a light source with adjustable wavelengths and intensities to adjust the light spectrum in real time according to the type of food, storage stage, and environmental conditions. This allows for the delay of food spoilage, inhibition of microbial growth, and maintenance of nutritional and sensory quality. The core principle is that different wavelengths of light have different effects on the biological and chemical processes in food. Blue light has antibacterial properties, red light helps maintain the physiological activity of fruits and vegetables, ultraviolet light can effectively kill bacteria, and white light can enhance the color development of food.
[0003] It is generally believed in the existing technology that the spoilage mechanisms of different foods are very different, and there is no universal preservation spectrum scheme. For example, meat spoilage is mainly related to microbial growth and requires focusing on the ultraviolet sterilization band, while fruit and vegetable preservation is mainly related to physiological metabolism and requires focusing on specific bands in visible light. Therefore, those skilled in the art generally believe that differentiated spectral strategies must be adopted for different types of food.
[0004] Current lighting for fresh food mainly focuses on color rendering and lacks active preservation functions. Moreover, most existing ultraviolet germicidal lamps are always on and cannot be intelligently adjusted, which may have a negative impact on some photosensitive foods and consume a lot of energy. Therefore, there is an urgent need for an intelligent preservation solution that can automatically adjust the sterilization spectrum and intensity according to the type of food and environmental conditions. Summary of the Invention
[0005] The purpose of this invention is to provide a food preservation method and system based on dynamic spectral adjustment, which has the advantage of automatic adaptive adjustment. It solves the problems that current lighting for fresh food mainly focuses on color rendering and lacks active preservation function. Moreover, most existing ultraviolet germicidal lamps are in a constant-on mode and cannot be intelligently adjusted, which may have a negative impact on some photosensitive foods, and they also have high energy consumption.
[0006] To achieve the above objectives, the present invention provides the following technical solution: a food preservation method based on dynamic spectral adjustment, comprising the following steps:
[0007] S1. Information Acquisition: Acquire target information about the food that needs to be preserved, as well as information about the food storage environment.
[0008] S2. Spectral decision: The acquired information is input into a preset spectral preservation control model. The spectral preservation control model has a built-in database that stores the preservation spectral formulas for different foods under different environments. The spectral preservation control model selects an appropriate preservation spectral formula based on the acquired information. The preservation spectral formula includes at least a combination of spectral parameters in the ultraviolet and visible light bands.
[0009] S3. Dynamic adjustment: Based on the spectral preservation control model, the system outputs decision commands to control the luminescence parameters of each independent channel in the multispectral LED module in real time, outputting a dynamically changing composite spectrum for targeted food preservation.
[0010] In a preferred embodiment of the food preservation method based on dynamic spectral adjustment of the present invention, the target information in S1 is the food type, which is obtained through image recognition or manual input. The food type includes meat, fruits and vegetables, and cooked food. The storage environment information includes temperature, humidity, and current time.
[0011] As a preferred embodiment of the food preservation method based on dynamic spectral adjustment of the present invention, when the S2 preservation spectral formula is formulated, the characteristic spectral band combinations of different food types are determined for different food types, and the parameters of the ultraviolet and visible light bands are determined for each characteristic spectral band combination. The food type, environmental parameters and corresponding characteristic spectral band combinations and optimization parameters are associated and stored to form a queryable spectral formula database.
[0012] As a preferred embodiment of the food preservation method based on dynamic spectral adjustment of the present invention, the method for determining the combination of characteristic spectral bands includes the following steps:
[0013] (1) For the target food type, the preservation effect of different wavelength combinations was tested by spectral irradiation experiment;
[0014] (2) Based on the preservation effect index, the optimal combination of characteristic spectral bands is selected;
[0015] (3) For each band in the optimal characteristic spectral band combination, optimize its intensity ratio and irradiation timing parameters.
[0016] As a preferred embodiment of the food preservation method based on dynamic spectral adjustment of the present invention, after the spectral preservation control model in S2 acquires food information and environmental information, it preprocesses the acquired raw information data and integrates the processed data into a feature unit. Based on the information contained in the feature unit, the preservation spectral formula is adapted.
[0017] In a preferred embodiment of the food preservation method based on dynamic spectral adjustment of the present invention, in step S2, the preservation spectral formulas stored in the database are arranged. First, a rule ID is assigned to each preservation spectral formula. The rule ID serves as a unique identifier for tracking and management. Then, the formulas are classified and ranked according to the values of each parameter in the preservation spectral formula.
[0018] In a preferred embodiment of the food preservation method based on dynamic spectral adjustment of the present invention, in step S2, when selecting the food preservation spectral formula, the information feature unit is matched with the rule ID, each condition in each rule is read, the corresponding actual value is extracted from the feature unit, and compared with the expected value defined in the rule. The rule with the closest comparison value is selected first, and the comparison value error is ±5%. Once a matching rule is found, the system immediately stops subsequent matching and retrieves the corresponding illumination parameters from the spectral formula library. If no match is found after traversing all rules, the default safe formula is automatically activated. The default safe formula is white light with a high color rendering index.
[0019] In a preferred embodiment of the food preservation method based on dynamic spectral adjustment of the present invention, the spectral formula selected in S2 is sent as a decision instruction to the LED driver controller. The LED driver controller generates a corresponding PWM dimming signal or constant current driving signal according to the parameters of each band in the spectral formula, and controls the luminous parameters of LED chips of different bands in the multispectral LED module respectively.
[0020] As a preferred embodiment of the food preservation method based on dynamic spectral adjustment of the present invention, during rule optimization, the historical preservation effect is evaluated periodically. If a rule fails to achieve the expected preservation target in multiple applications, a rule correction mechanism is triggered, and the condition threshold or associated formula of the rule is adjusted by manual intervention. In addition, the accumulated matching and effect data are used to train the learning model to generate better rule suggestions, which are then reviewed by the operation and maintenance personnel and incorporated into the rule base. Through the closed-loop mechanism of execution, monitoring, evaluation and iteration, the rule base is continuously optimized and improved, thereby enhancing the accuracy, adaptability and preservation efficiency of spectral decision-making.
[0021] Food preservation systems based on dynamic spectral modulation include:
[0022] The sensing layer detects the temperature, humidity, and time of the storage environment through environmental sensors, identifies the type of food through image recognition or manual input, and monitors the food preservation status through odor sensors or image sensors.
[0023] The decision layer receives the detection information from the perception layer and, through the allocation algorithm and the preservation spectrum formula database, adapts the preservation spectrum formula to match the food.
[0024] The execution layer receives decision instructions from the decision-making layer and controls the multispectral LED module according to the preservation spectrum formula, outputting a dynamically adjusted composite preservation spectrum.
[0025] The multispectral LED module in the execution layer has LED chips of different wavelengths arranged in partitions, and physical or optical isolation structures are provided between the optical paths of each partition, so as to achieve the separate control of each independent channel as described in claim 1.
[0026] A method for managing lighting for the preservation of fresh produce, comprising:
[0027] During business hours, the multispectral LED module is controlled to prioritize the output of high color rendering visible light;
[0028] During non-business hours, the multispectral LED module is switched to a sterilization spectrum dominated by ultraviolet light.
[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0030] 1. This invention integrates food information sensing, intelligent spectral decision-making, and multi-channel LED precise control to achieve personalized and dynamic preservation lighting for different foods under different storage environments. This method breaks through the limitations of traditional fixed spectrum or single white light lighting. It can automatically match the optimal composite spectrum formula according to the food type and its environmental parameters such as temperature, humidity, and gas composition. This includes the wavelength, intensity, and duty cycle of ultraviolet light and the scientific ratio of visible light. This results in a multi-dimensional improvement in preservation effect, such as inhibiting microbial growth, delaying enzymatic browning, maintaining color and flavor, and retaining nutrients. In particular, through high-precision LED driving control, the light not only has a display and beautification function, but also becomes a preservation method that actively intervenes in the physiological and microbial processes of food, significantly extending shelf life and reducing food loss.
[0031] 2. By recording the rule ID and input features hit in each decision and combining them with subsequent preservation effect evaluation, the system can identify inefficient or ineffective rules, support manual correction or use machine learning models to generate optimization suggestions, and realize dynamic updates and iterative upgrades of the rule base. This not only improves the accuracy and adaptability of spectral decision-making, but also ensures that the preservation strategy is always based on the latest empirical data and scientific understanding. At the same time, the default safe formula mechanism ensures the compliance and safety of basic lighting in unknown scenarios and avoids misleading consumers. Overall, this method combines technological advancement, practical application and commercial sustainability. Attached Figure Description
[0032] Figure 1 This is a flowchart of the method of the present invention;
[0033] Figure 2 This is a system block diagram of the present invention. Detailed Implementation
[0034] Example 1
[0035] Please see Figure 1 A food preservation method based on dynamic spectral modulation includes the following steps:
[0036] S1. Information Acquisition: Acquire target information about the food that needs to be preserved, as well as information about the food storage environment.
[0037] S2. Spectral decision: The acquired information is input into a preset spectral preservation control model. The spectral preservation control model has a built-in database that stores the preservation spectral formulas for different foods under different environments. The spectral preservation control model selects an appropriate preservation spectral formula based on the acquired information. The preservation spectral formula includes at least a combination of spectral parameters in the ultraviolet and visible light bands.
[0038] S3. Dynamic adjustment: Based on the spectral preservation control model, the system outputs decision commands to control the luminescence parameters of each independent channel in the multispectral LED module in real time, outputting a dynamically changing composite spectrum for targeted food preservation.
[0039] Furthermore, when formulating the S2 preservation spectral formula, the characteristic spectral band combinations for different food types are determined. For each characteristic spectral band combination, the parameters of its ultraviolet and visible light bands are determined. The food type, environmental parameters, and corresponding characteristic spectral band combinations and optimization parameters are associated and stored to form a queryable spectral formula database.
[0040] Furthermore, the method for determining the combination of characteristic spectral bands includes the following steps:
[0041] (1) For the target food type, the preservation effect of different wavelength combinations was tested by spectral irradiation experiment;
[0042] (2) Based on the preservation effect index, the optimal combination of characteristic spectral bands is selected;
[0043] (3) For each band in the optimal characteristic spectral band combination, optimize its intensity ratio and irradiation timing parameters.
[0044] Furthermore, the S3 multispectral LED module includes ultraviolet light and visible light, with the visible light being white, red, blue, or green.
[0045] Furthermore, after the S2 spectral preservation control model acquires food and environmental information, it preprocesses the acquired raw data and integrates the processed data into a feature unit. Based on the information contained in the feature unit, the preservation spectral formula is adapted.
[0046] Furthermore, in S2, the preservation spectrum recipes stored in the database are arranged. First, a rule ID is assigned to each preservation spectrum recipe. The rule ID serves as a unique identifier for tracking and management. Then, the recipes are classified and ranked according to the values of each parameter in the preservation spectrum recipe.
[0047] Furthermore, in S2, when selecting the food preservation spectrum formula, the information feature unit is matched with the rule ID. Each condition in each rule is read, the corresponding actual value is extracted from the feature unit, and compared with the expected value defined in the rule. The rule with the closest comparison value is selected first, with a comparison value error of ±5%. Once a matching rule is found, the system immediately stops subsequent matching and retrieves the corresponding illumination parameters from the spectrum formula library. If no match is found after traversing all rules, the default safe formula is automatically activated. The default safe formula is white light with a high color rendering index.
[0048] Furthermore, the spectral formula selected in S2 is sent to the LED driver controller as a decision instruction. The LED driver controller generates corresponding PWM dimming signals or constant current driving signals according to the parameters of each band in the spectral formula, and controls the light emission parameters of LED chips of different bands in the multispectral LED module respectively.
[0049] Furthermore, during rule optimization, historical preservation effects are periodically evaluated. If a rule fails to achieve the expected preservation target in multiple applications, a rule correction mechanism is triggered, allowing manual intervention to adjust the rule's condition thresholds or associated formulas. The accumulated matching and effect data are also used to train a learning model to generate better rule suggestions, which are then reviewed by operations and maintenance personnel and incorporated into the rule base. Through a closed-loop mechanism of execution, monitoring, evaluation, and iteration, the rule base is continuously optimized and improved, enhancing the accuracy, adaptability, and preservation efficiency of spectral decision-making.
[0050] This food preservation method integrates food information sensing, intelligent spectral decision-making, and precise multi-channel LED control to achieve personalized and dynamic preservation lighting for different foods under different storage environments. This method breaks through the limitations of traditional fixed spectrum or single white light lighting. It can automatically match the optimal composite spectrum formula according to the food type and its environmental parameters such as temperature, humidity, and gas composition. This includes the wavelength, intensity, and duty cycle of ultraviolet light and the scientific ratio of visible light. This synergistically improves the preservation effect in multiple dimensions, such as inhibiting microbial growth, delaying enzymatic browning, maintaining color and flavor, and retaining nutrients. In particular, through high-precision LED drive control, the light not only has a display and beautification function, but also becomes a preservation means of actively intervening in the physiological and microbial processes of food, significantly extending shelf life and reducing food loss.
[0051] Furthermore, this method constructs a closed-loop intelligent system encompassing "perception-decision-execution-feedback-optimization," possessing continuous evolution capabilities. By recording the rule IDs and input features hit in each decision and combining this with subsequent preservation effect evaluations, the system can identify inefficient or ineffective rules, supporting manual correction or the generation of optimization suggestions using machine learning models. This enables dynamic updates and iterative upgrades of the rule base, which not only improves the accuracy and adaptability of spectral decision-making but also ensures that preservation strategies are always based on the latest empirical data and scientific understanding. Simultaneously, the default safety formula mechanism guarantees the compliance and safety of basic lighting in unknown scenarios, avoiding misleading consumers. Overall, this method combines technological advancement, practical application, and commercial sustainability, providing a green, efficient, and scalable solution for intelligent cold chain, fresh food retail, and home preservation scenarios.
[0052] The core innovation of this invention lies in the discovery that different combinations of characteristic spectral bands are needed for different types of food, rather than simply adjusting the light intensity or duty cycle. Experiments show that using a 'one-size-fits-all' general spectral scheme results in a 30%-50% decrease in preservation effect compared to a targeted approach.
[0053] Experiments have shown that using a specific combination of 460nm blue light and 660nm red light (intensity ratio 3:2, intermittent irradiation) on leafy green vegetables increases vitamin C retention by 40% and extends shelf life by 3 days compared to traditional white light illumination.
[0054] In order to achieve the preservation effect of 460nm blue light band while avoiding discomfort to consumers from looking directly at pure blue light, a specific proportion of red and green phosphors can be added to the packaging material of the corresponding LED chip. After mixing, it will appear as natural white light without affecting the essential output spectrum of the blue light band.
[0055] A method for managing lighting for the preservation of fresh produce, comprising:
[0056] During business hours, the multispectral LED module is controlled to prioritize the output of high color rendering visible light;
[0057] During non-business hours, the multispectral LED module is switched to a sterilization spectrum dominated by ultraviolet light.
[0058] Example 2
[0059] Please see Figure 2 A food preservation system based on dynamic spectral modulation includes:
[0060] The sensing layer detects the temperature, humidity, and time of the storage environment through environmental sensors, identifies the type of food through image recognition or manual input, and monitors the food preservation status through odor sensors or image sensors.
[0061] The decision layer receives the detection information from the perception layer and, through the allocation algorithm and the preservation spectrum formula database, adapts the preservation spectrum formula to match the food.
[0062] The execution layer receives decision instructions from the decision-making layer and controls the multispectral LED module according to the preservation spectrum formula, outputting a dynamically adjusted composite preservation spectrum.
[0063] The food preservation system based on dynamic spectral adjustment can be used in fresh produce display areas. The system is deployed above the fresh produce display area. When the system detects that new food has been placed in the display area, it automatically identifies the food type and activates the corresponding preservation spectral formula. During business hours, it prioritizes the use of high color rendering visible light mode, and during non-business hours, it switches to high-efficiency ultraviolet sterilization mode.
[0064] The multispectral LED module in the execution layer has LED chips of different wavelengths arranged in partitions, and physical or optical isolation structures are provided between the optical paths of each partition, so as to achieve the separate control of each independent channel as described in claim 1.
[0065] The system can also be used in fresh food retail cabinets to keep food in snack cabinets fresh.
[0066] The food preservation system based on dynamic spectral adjustment constructs a three-tiered collaborative architecture of "perception layer – decision layer – execution layer," enabling intelligent, precise, and dynamic management of the food preservation process. The perception layer integrates multimodal sensing technology, not only collecting basic parameters such as ambient temperature and humidity and storage time in real time, but also automatically identifying food types through image recognition and dynamically monitoring the freshness status of food in conjunction with odor or visual sensors, providing comprehensive and accurate data support for preservation decisions. The decision layer, relying on a built-in preservation spectral formula database and intelligent allocation algorithm, can quickly match the optimal composite spectral scheme based on multidimensional information such as the current food type and status, and environmental conditions. The execution layer, through high-precision control of multispectral LED modules, outputs dynamic lighting with adjustable wavelength, intensity, and duty cycle, achieving targeted preservation intervention for different foods, effectively inhibiting microbial growth, delaying physiological aging, maintaining sensory quality, significantly extending shelf life, and reducing losses.
[0067] The system also boasts excellent scalability, security, and sustainable optimization capabilities. On one hand, through modular design, the perception layer can flexibly configure sensor combinations according to application scenarios, the decision-making layer supports online updates of rule bases or AI models, and the execution layer is compatible with various LED light source solutions, making it suitable for various scenarios such as supermarket freezers, cold chain transportation, and smart refrigerators. On the other hand, when there is no clear matching solution, the system automatically uses high color rendering index white light as the default safe lighting to ensure that consumers are not misled and to meet regulatory requirements for food safety and transparent display. More importantly, the system can record the correlation data between each decision and the preservation effect, forming a closed-loop feedback mechanism. This provides a data foundation for subsequent rule optimization, formula iteration, and preservation strategy upgrades, driving the evolution of preservation technology from experience-driven to data-intelligent driven. Overall, the system not only improves the scientific nature and efficiency of food preservation but also provides strong support for reducing food waste, ensuring consumer safety, and promoting green and intelligent retail.
[0068] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A food preservation method based on dynamic spectral modulation, characterized in that, Includes the following steps: S1. Information Acquisition: Acquire target information about the food that needs to be preserved, as well as information about the food storage environment. S2. Spectral decision: The acquired information is input into a preset spectral preservation control model. The spectral preservation control model has a built-in database that stores the preservation spectral formulas for different foods under different environments. The spectral preservation control model selects an appropriate preservation spectral formula based on the acquired information. The preservation spectral formula includes at least a combination of spectral parameters in the ultraviolet and visible light bands. S3. Dynamic adjustment: Based on the spectral preservation control model, the system outputs decision commands to control the luminescence parameters of each independent channel in the multispectral LED module in real time, outputting a dynamically changing composite spectrum for targeted food preservation.
2. The food preservation method based on dynamic spectral adjustment according to claim 1, characterized in that: The target information in S1 is the food type, which is obtained through image recognition or manual input. Food types include meat, fruits and vegetables, and cooked food. The storage environment information includes temperature, humidity, and current time.
3. The food preservation method based on dynamic spectral adjustment according to claim 1, characterized in that: When formulating the S2 preservation spectral formula, for different food types, the characteristic spectral band combinations of different food types are determined. For each characteristic spectral band combination, the parameters of its ultraviolet and visible light bands are determined. The food type, environmental parameters, and corresponding characteristic spectral band combinations and optimization parameters are associated and stored to form a queryable spectral formula database.
4. The food preservation method based on dynamic spectral adjustment according to claim 3, characterized in that: The method for determining the combination of characteristic spectral bands includes the following steps: (1) For the target food type, the preservation effect of different wavelength combinations was tested by spectral irradiation experiment; (2) Based on the preservation effect index, the optimal combination of characteristic spectral bands is selected; (3) For each band in the optimal characteristic spectral band combination, optimize its intensity ratio and irradiation timing parameters.
5. The food preservation method based on dynamic spectral adjustment according to claim 1, characterized in that: After acquiring food and environmental information, the spectral preservation control model in S2 preprocesses the acquired raw data and integrates the processed data into a feature unit. Based on the information contained in the feature unit, the preservation spectral formula is adapted.
6. The food preservation method based on dynamic spectral adjustment according to claim 1, characterized in that: In step S2, the preservation spectrum formulas stored in the database are arranged. First, a rule ID is assigned to each preservation spectrum formula. The rule ID serves as a unique identifier for tracking and management. Then, the formulas are classified and ranked according to the values of each parameter in the preservation spectrum formula.
7. The food preservation method based on dynamic spectral adjustment according to claim 1, characterized in that: In step S2, when selecting the food preservation spectrum formula, the information feature unit is matched with the rule ID. Each condition in each rule is read, the corresponding actual value is extracted from the feature unit, and compared with the expected value defined in the rule. The rule with the closest comparison value is selected first, and the comparison value error is ±5%. Once a matching rule is found, the system immediately stops subsequent matching and retrieves the corresponding illumination parameters from the spectrum formula library. If no match is found after traversing all rules, the default safe formula is automatically activated. The default safe formula is white light with a high color rendering index.
8. The food preservation method based on dynamic spectral adjustment according to claim 1, characterized in that: The spectral formula selected in S2 is sent to the LED driver controller as a decision instruction. The LED driver controller generates corresponding PWM dimming signals or constant current driving signals according to the parameters of each band in the spectral formula, and controls the light emission parameters of LED chips of different bands in the multispectral LED module respectively.
9. The food preservation method based on dynamic spectral adjustment according to claim 8, characterized in that: When optimizing rules, historical preservation effects are evaluated regularly. If a rule fails to achieve the expected preservation goal in multiple applications, a rule correction mechanism is triggered, and manual intervention is used to adjust the condition threshold or associated formula of the rule. The accumulated matching and effect data are also used to train a learning model to generate better rule suggestions, which are then reviewed by operations and maintenance personnel and incorporated into the rule base. Through a closed-loop mechanism of execution, monitoring, evaluation, and iteration, the rule base is continuously optimized and improved to enhance the accuracy, adaptability, and preservation efficiency of spectral decision-making.
10. A food preservation system based on dynamic spectral modulation, characterized in that, include: The sensing layer detects the temperature, humidity, and time of the storage environment through environmental sensors, identifies the type of food through image recognition or manual input, and monitors the food preservation status through odor sensors or image sensors. The decision layer receives the detection information from the perception layer and, through the allocation algorithm and the preservation spectrum formula database, adapts the preservation spectrum formula to match the food. The execution layer receives decision instructions from the decision-making layer and controls the multispectral LED module according to the preservation spectrum formula, outputting a dynamically adjusted composite preservation spectrum. The multispectral LED module in the execution layer has LED chips of different wavelengths arranged in partitions, and physical or optical isolation structures are provided between the optical paths of each partition, so as to achieve the separate control of each independent channel as described in claim 1.
11. A method for managing lighting for the preservation of fresh produce, characterized in that, The method described in any one of claims 1-9, and comprising: During business hours, the multispectral LED module is controlled to prioritize the output of high color rendering visible light; During non-business hours, the multispectral LED module is switched to a sterilization spectrum dominated by ultraviolet light.