Visible light is not the only electromagnetic wave that is available in the electromagnetic spectrum. Along with the light, there are different types of rays with different ranges of wavelengths. The infrared rays and the ultraviolet rays are some of the most important rays in the spectrum. The below article explains the properties of the rays and how they can be used in sensing applications.
Contents:
- What is an Infrared Ray?
- What are Ultraviolet Rays?
- Comparison between IR and UV Rays
- Infrared Sensors
- Ultraviolet Ray Sensors
- Types of IR Sensors and their Applications
- Types of UV Sensors and their Applications
- Industrial Usage of IR Sensors and UV Sensors
What is an Infrared Ray?
The infrared radiation is most commonly known as the infrared. The infrared rays have wavelengths ranging between 700 nanometres to 1 millimetre. Some of the basic properties of infrared rays are listed below.
- The infrared is not visible to the human eyes as the wavelength of the infrared radiation is higher than that of the visible light.
- Though some properties of visible light like polarization and reflection are applicable to infrared rays as well.
- Infrared radiation can pass through gas whose density is high and also pass through the dusty atmosphere.
- The infrared spectrum is classified into five types based on their wavelengths and their position in the electromagnetic spectrum.
- They are – near-infrared waves, short-infrared waves, mid-infrared waves, long-infrared waves, and far-infrared waves.
What are Ultraviolet Rays?
The ultraviolet radiation or UV rays is also part of the electromagnetic spectrum. The wavelength range of the ultraviolet rays is from 100 nanometers to 400 nanometers. Other properties and the characteristics of the IV rays are as follows:
- The sun is the main source of ultraviolet rays. People living in the equator are most commonly exposed to the UV rays from the sun.
- The ultraviolet rays are highly reflective that they can even get reflected by surfaces like snow, water and even grass.
- If a person is constantly exposed to ultraviolet rays, he/she is prone to skin diseases and a worst-case scenario i.e., skin cancer.
- The ultraviolet rays have the property to destroy some types of bacteria and viruses.
- The ultraviolet ray is the high energy spectrum that is also used in disinfecting and sterilizing medical instruments.
Comparison between IR and UV Rays
The differences and similarities between the infrared rays and the ultraviolet rays concerning their wavelengths and other properties are explained in the table below.
| Parameters | Infrared rays | Ultraviolet rays |
|---|---|---|
| Wavelength range | Has a wavelength ranging from 700 nm to 1 mm | Has a wavelength ranging from 100 nm to 400 nm |
| Energy Spectrum | Is a low energy spectrum with a wavelength slightly higher than the microwaves | Is a high energy spectrum with a wavelength higher than that of the visible light |
| Number of Types | Is divided into five types based on the wavelength | Is divided into three types based on the position in the spectrum |
| Types | Near-infrared waves, short-infrared waves, mid-infrared waves, long-infrared waves, and far-infrared waves. | UVA rays – UV rays with the least energy UVB rays – UV rays with higher energy than UVA UVC rays – UV rays with the maximum energy |
| Illumination Property | Has no illumination properties | Has no illumination property but glows when exposed to a fluorescent substance |
| Applications | Is used in night vision glasses, and thermal imaging etc. | Is used in spectroscopy and the sterilization of medical instruments. |
Infrared Sensors
The infrared sensor is a device that uses infrared light to detect objects and also to monitor the motion of the object. The infrared sensors can sense the electromagnetic spectrum with a wavelength ranging from 780 nm to 50 µm. The construction and working of the infrared sensors are as follows:
- The infrared sensor consists of an infrared LED and an infrared photodiode along with some additional circuits which consist of resistors with variable resistance values.
- At first, the infrared LED emits some infrared radiation that will not be visible to the human eyes.
- When the rays from the LED have no obstacles in front of it, it moves further and does not bounce back.
- If an obstacle is present in the path of the infrared ray, then the rays will get reflected by the material and bounce back.
- Black coloured objects are the exceptions for the infrared rays. The colour black tends to absorb the infrared rays from the LED.
- Thus, an IR sensor cannot detect a black object.
Ultraviolet Ray Sensors
The ultraviolet ray sensor is a device that is used to measure the distance between an object and the sensor. There are different types of UV sensors that are used for various applications. The generalized construction and the working of the UV sensors are explained below.
- The ultraviolet sensor consists of an ultrasonic transmitter and an ultrasonic sensor just like the IR sensor.
- The transmitter transmits an ultrasonic wave with a frequency of 40 kilohertz.
- If there is an object present in front of the sensor within the distance of 400 cm, the sensor can able to sense the distance between the object and the sensor.
- Unlike the infrared sensor, the UV sensor provides the output in form of a number indicating the distance.
Types of IR Sensors and Their Applications
The infrared sensor is broadly classified into two types based on the nature of the external power supply they require for their functioning. They are active IR sensors and passive IR sensors. This classification and its application are explained further below.
- An active IR sensor is a device that consists of both LED and IR photodiode. This is the most commonly used type of IR sensor.
- Another best fact about these sensors is that the output provided by this type of sensor can be easily used for further signal processing.
- Passive IR sensors do not have a LED for transmission. This is used to measure the intensity of the infrared rays in the atmosphere.
- Infrared sensors are used in many fields like meteorology, gas analysis etc.
- They are also used in burglar alarms which can be used in the field of home automation.
Types of UV Sensors and Their Applications
The ultraviolet sensors are classified into three different types based on their specifications like the wavelength range, accuracy, operating temperature etc. All the types and the real-time applications of the sensors are explained below.
- One of the main classifications of UV sensors is ultraviolet phototubes. They are used in applications that involve medical treatments using ultraviolet rays.
- The second classification of UV sensors is light sensors. This is the most commonly used UV sensor and is used in small scale applications.
- The last and the most complicated type of UV sensor is the ultraviolet spectrum sensor.
- The spectrum sensor is the charged couple device that is used in the field of scientific photography.
- They are also used in the determination of exposure to ultraviolet radiation for industrial and dermatological purposes.
Industrial Usage of IR Sensors and UV Sensors
Though infrared sensors and ultraviolet sensors are devices with less complicated construction and working, they are used in various industrial applications. Some of the major applications of IR sensors and UV sensors which are of industrial level are stated below.
- Non-contact type temperature measurements in various industries use infrared sensing for temperature measurement.
- They are used in industries that involve constant temperature monitoring like food industries, plastic industries etc.
- IR sensors are also used in the manufacture of flame monitors which is similar to fire alarms in buildings.
- Ultraviolet sensors are used in dyeing industries and processes involving techniques like printing.
- They are also used in chemical industries at various stages of manufacture from production to storage.
Key Points to Remember
Here are some key points we need to remember about “infrared sensors and ultraviolet sensors”
- Infrared wave is an electromagnetic radiation with wavelength ranging from 700 nm to 1 mm.
- Ultraviolet rays are a high energy electromagnetic spectrum that is directly emitted by the sun itself.
- Both infrared and ultraviolet rays are invisible to the human eye.
- Infrared sensors use infrared radiation to detect the availability of an obstacle within a certain range.
- Ultraviolet sensors are devices that use UV rays to measure the distance between an object and the sensor.
- Infrared sensors are widely classified into two types based on their energy requirement – Active and passive.
- Ultraviolet sensors are classified into three types based on their specifications – Ultraviolet phototubes, light sensors and UV spectrum sensors.
