A Casual Talk on Infrared Measurement

In recent years, measuring body temperature has been one of the top three things to do before going out. With the widespread use of handheld temperature guns—infrared thermometers, "infrared testing" has entered the public's view.Users of infrared thermometers aim the infrared light spot at the surface of the target object through the device's sight. At this time, the infrared detector equipped inside the thermometer senses the infrared radiation emitted from the target surface and converts it into an electrical signal. The received electrical signal is processed by the internal microprocessor of the device, converted into a temperature reading, and displayed on the screen.

Schematic diagram of a simple infrared thermometer.

Although both the infrared coating/moistureSensor developed by our company and the infrared thermometer contain the word "infrared," their measurement principles are not the same.

Although the principles are different, they both originate from "infrared light." So what is infrared light?Infrared light is a type of electromagnetic radiation with wavelengths between visible light and microwaves, approximately ranging from 0.7 micrometers to 1000 micrometers, spanning three orders of magnitude, which our eyes cannot perceive.The wavelength range of visible light is typically between 0.38 micrometers and 0.750 micrometers. Light waves in this range are visible to the human visual system, hence it is called the visible spectrum.

Due to the broader wavelength range of infrared light, its good permeability in the atmosphere, and the unique absorption characteristics of some objects in the infrared spectrum, infrared spectral analysis technology is widely used in various fields, including the following aspects:

l Chemistry and Materials Science: Infrared testing is a common analytical method in the fields of chemistry and materials science. It can be used to analyze the structure, components, and functional groups of substances, thus being widely applied in the identification of chemicals, drug development and manufacturing, and quality control of materials.

l Food and Agriculture: Infrared testing also has important applications in the food and agriculture sectors. Infrared spectroscopy technology can analyze the components, nutrients, and contaminants in food, ensuring food safety and quality. In agriculture, infrared testing can also be used for soil analysis, crop quality testing, and more.

l Drug Development and Medical Diagnosis: In the drug development process, infrared testing can be used for the analysis and identification of drug components, helping pharmaceutical companies ensure product quality and stability. In medical diagnosis, infrared spectroscopy technology is also applied in medical imaging and biomolecular structure research.

l Environmental Monitoring: Infrared testing can be used for environmental monitoring and pollutant detection. Infrared spectroscopy technology can monitor the gas components in the atmosphere, detect harmful substances in the air, and monitor organic matter and heavy metals in industrial wastewater.

l Security and Defense: Infrared testing technology has important applications in security and defense. For example, infrared imaging technology can be used in night vision devices, monitoring systems, fire detection, etc., helping to ensure the safety of personnel and equipment.

In addition to the different measurement principles, temperature measurement is a form of passive infrared testing. The infrared Sensor developed by our company belongs to active infrared testing.

Active Infrared:

Active infrared sensors detect target objects by emitting infrared radiation and then detecting the returned infrared signals to identify the presence, distance, and other attributes of the object. This technology is commonly used in infrared remote controls, infrared rangefinders, and other devices.

Active infrared sensors typically consist of an infrared emitter and a receiver. The emitter emits infrared light of a specific wavelength, which is reflected or absorbed when it encounters an object. The receiver detects the reflected or absorbed signals and determines the nature and location of the object based on the signal's intensity and timing.

The advantages of active infrared technology include the ability to work under various environmental conditions, a longer detection range for targets, and a fast response speed.

Passive Infrared:

Passive infrared sensors detect and identify based on the infrared signals emitted by the target object itself. Passive infrared sensors are commonly used in human detection, animal monitoring, temperature detection, and other fields.

Passive infrared sensors utilize the infrared radiation generated by the target object itself, detecting changes in this radiation to determine the presence, location, or other characteristics of the target object. This technology is commonly used in security systems, automatic lighting systems, and other applications.

The advantages of passive infrared technology include no need for an additional energy source, no interference with the target object, and suitability for low-power and long-term monitoring scenarios.

To be more precise, our infrared Sensor is an "active near-infrared component testing sensor based on absorption spectrum with filter."

The absorption spectrum of near-infrared is mostly produced by molecular bonds formed by hydrogen atoms and other atoms, and these absorption wavelengths are selectively unique.

The most common elements in the universe are usually ranked according to their abundance in the universe. Based on current astronomical observations and theoretical models, here are the top 20 most common elements in the universe, listed in order of their abundance:

Hydrogen

Helium

Oxygen

Carbon

Nitrogen

Visible OH, CH, and NH are the most common combinations, so materials related to these molecules can mostly be quickly tested for their component content through infrared testing in a non-contact manner.

Typical applications include moisture testing related to OH, polymer materials related to CH, and thickness testing of coatings and plastic films. By projecting through a filter onto the surface of the tested material and comparing the changes in reflected energy, the component content related to that molecule can be tested. Therefore, our infrared Sensor measures the surface of objects, which is suitable for surface treatments such as coating, but it cannot penetrate.

Filter-based near-infrared testing has certain advantages in specific application scenarios:

1. Lower cost: Compared to some high-end spectroscopic instruments, filter-based near-infrared testing instruments are usually lower in cost, making them more suitable for laboratories or application scenarios with limited budgets.

2. Simple and easy to use: This testing method is usually simple to operate, requiring no complex setup and calibration processes, allowing users to quickly get started and conduct sample tests.

3. Suitable for general testing: For some general applications where the accuracy requirements are not particularly high, near-infrared testing based on filters can provide sufficient analytical results to meet basic needs.

In general, our infrared Sensor can indirectly test the content of components related to OH, CH, and NH by testing their near-infrared absorption spectra, thus having wide applications in automated production control.

Welcome to communicate and discuss with us.