How Does Infrared Work

Infrared (IR) light is a wavelength of energy that is invisible to the human eye. The most common source of this energy is heat; objects can have their relative temperatures measured by how much of this energy they give off. Lower wavelengths or "near infrared" — closest to the visible light color red — are not hot, and are often used to transmit data in electronics. A remote control, for example, may use a particular wavelength of near infrared to communicate with a receiver, sending pulses of light that transmit a signal to the device, telling it what to do.

Description and Measurement

A form of energy, IR is part of the electromagnetic spectrum. This spectrum is comprised of radio waves; microwaves; infrared, visible, and ultraviolet light; x-rays; and gamma rays. Each form of energy is ordered by wavelength; infrared falls between microwaves and visible light waves because its waves are shorter than microwaves but longer than those of visible light.

The prefix infra comes from the Latin word which means "below;" the term means "below red," indicating its position in the electromagnetic spectrum. Visible light has a range of wavelengths that are manifested in the seven colors of the rainbow; red has the longest wavelength and violet has the shortest. Infrared, with wavelengths longer than the color red, is invisible to the human eye.

Just like with visible light, there are a range of wavelengths of IR. The International Commission on Illumination has divided it into three general sections based on the length of the wave and density. These groups are commonly known as near, medium, and far infrared, with near infrared being nearest to the visible light side of the spectrum and far, or long-wave, infrared being close to the microwave zone. There are uses for IR wavelengths in each group, from wireless communication to acting as heat source.

Applications of Infrared

Nearly all objects emit heat or energy, and one of the most easily discernible forms of energy is infrared. When an object is not hot enough to give off visible light, it emits most of its energy in the IR spectrum. It is this heat that affords IR many applications in almost every sector of life, including health, science, industry, art, and entertainment.

Converting infrared energy, also known as radiant heat, into an image that the human eye can see and understand is done with a process called thermal imaging. An IR camera is used to accurately measure the temperature of an object, which is then translated into color. For example, infrared imaging typically shows the warmest areas in a human body as red, followed by yellow, green, blue, and violet as the temperature decreases. By studying how body heat is distributed, thermal imaging can health professionals to analyze body tissue and fluid to detect injury or disease.

Infrared light is used in night vision equipment, allowing the user to see in the dark. Two types of night vision both use IR: thermal and image-intensifying. Thermal night vision allows the user to recognize people and objects by the heat pattern they emit. Intensifiers amplify existing light — including infrared — to allow the user to see.

As a way to measure temperature, IR is used in many different types of applications. The military uses infrared sensors to locate and track targets or to detect hidden land mines or arms caches. Infrared sensors on satellites are used for environmental monitoring, pinpointing areas of pollution, fire, or deforestation. Search and rescue operations use IR extensively to locate missing persons lost in the forest or jungle, as well as in collapsed buildings or at the site of other disasters.

Many remote control devices in homes use infrared. These remotes use infrared light to carry signals between a remote control transmitter and the device it's commanding. The transmitter sends out light in pulses, which are translated into binary codes that have corresponding commands. The receiver is positioned on the front of the device, where it receives these pulses of light and decodes them into binary data, which is understood by the microprocessor inside the apparatus. 

Many different types of scientists use infrared in their work, from astronomers use it to learn more about galaxies light years away to archaeologists who use it when studying ancient settlements. Infrared is being used to preserve, restore, and conserve valuable historical and artistic works as well; the invisible details of ancient fragments and images painted under paintings are being brought to light through the use of IR technology. In industry, thermal imaging is invaluable in testing and monitoring mechanical systems.

What is the Difference Between NTSC and PAL

Some Americans may have sent video home movies to a European relative, only to discover that the images are scrambled and the sound quality is very poor. This is caused by a major difference in broadcast formats used by the United States and many other countries. The United States favors a format called NTSC, which is short for National Television Standards Committee, while Europe, Australia and parts of Asia use a competing format called PAL, or Phase Alternating Line.

Most of us would not be able to recognize the difference between NTSC and PAL, but then again most of us aren't television broadcast engineers. The differences really start with the electrical power system behind the transmissions. In the United States and other countries, electrical power is generated at 60 hertz, so for technical reasons the NTSC signal is also sent out at 60 'fields' per second. Since most televisions use an interlaced system, this means that 30 lines of the image are sent out, followed by the alternating 30 lines. This line alternation happens so fast that it becomes undetectable, much like a film running through a projector. The result for an NTSC television is 30 frames of a complete image appearing every second.

Since Europe uses a 50 hertz power supply, the equivalent PAL lines go out at 50 fields per second, or 25 alternating lines. PAL televisions only produce 25 complete frames per second, which can cause some problems with the proper display of motion. Think of it as the 'silent movie effect', in which the actors seem to move a little faster because there are fewer frames showing movement. If a PAL movie is converted to an NTSC tape, 5 extra frames must be added per second or the action might seem jerky. The opposite is true for an NTSC movie converted to PAL. Five frames must be removed per second or the action may seem unnaturally slow.

Another difference between NTSC and PAL formats is resolution quality. PAL may have fewer frames per second, but it also has more lines than NTSC. PAL television broadcasts contain 625 lines of resolution, compared to NTSC's 525. More lines usually means more visual information, which equals better picture quality and resolution. Whenever an NTSC videotape is converted to PAL, black bars are often used to compensate for the smaller screen aspect, much like letterboxing for widescreen movies. 

When the NTSC format was first adopted in 1941, there was little discussion of color transmissions. When the technology for color television arrived, engineers had to create a broadcast method which would still allow owners of monochrome television sets to receive a picture. Color signals on the NTSC format are still not considered ideal by electronics experts. The PAL system, on the other hand, was created after the advent of color broadcasting, so color signals are much truer to the original image.

For most purposes, the difference between NTSC and PAL signals are negligible. A European television set won't work in the United States and an NTSC formatted DVD won't play on a PAL player. But many people own home movies which cannot be viewed on a competing format. For this reason, there are a number of companies which offer conversion kits from NTSC to PAL or PAL to NTSC. Some of these conversion methods can be time-consuming and variable in quality, but others provide an easy way to create a PAL video for a European relative or an NTSC DVD for a Canadian friend. Some electronic media outlets may also provide conversion services for a price.

What Is the Difference Between a Line Conditioner and a Surge Protector

The difference between a line conditioner and a surge protector mostly lies in their intended function. A line conditioner takes in power and modifies it based on the requirements of the machinery to which it is connected. A surge protector doesn't alter the power flowing through it at all, unless that power is over a certain amount. When the power exceeds the set amount, it blocks it from passing through. It is not uncommon for a line conditioner and a surge protector to be in the same unit.

Both a line conditioner and a surge protector are important parts of modern electronics. They protect the inner workings of devices, often without users even realizing. Many people go the extra step of placing these devices between the wall outlets and connected devices to create an additional layer of protection.

A line conditioner modifies voltage as it passes through. Some systems require very tight or nonstandard power tolerances. These devices use line conditioners to alter the power to meet their requirements. They are also a common method of prolonging the lifespan of electric devices, as the properly formed electricity creates less wear of the internal parts of the device.

Most electric systems have line conditioners built into them. These units are usually very small and integrated right into the circuit board inside the device. They monitor the voltage moving across the board and keep it within tolerance. Larger line conditioners exist, ranging from small ones in high-end surge protectors all the way to car-sized industrial units connected to factory machines.

Surge protectors prevent power overloads. When power exceeds a certain amount, they stop it from passing through. Different surge protectors do this in different ways, but the most common method is creating a shunt to a ground wire. 

This connection to the ground only happens when the power is prevented from passing through the unit; otherwise, the unit would constantly waste electricity. If a surge protector is improperly plugged in, such as through a two- or three-pronged adapter, it cannot send power to the ground. In this case, the surge protector may overload and catch on fire or even send the surge through to the connected device.

It isn't unusual for a line conditioner and a surge protector to exist in the same unit. Since these systems both work on passing voltage, it is logical for them to exist together. Some systems only possess a very advanced line conditioner that works as a surge protector when needed; this is common in battery backup systems. In either case, both a line conditioner and a surge protector are important aspects of safe electric device use.