What Is Thermal Imaging?
A thermal imaging camera detects the amount of infrared energy—not
visible to the human eye—emitted, transmitted and reflected by
objects. Algorithms are then used to display that energy in a visible
image. Everything near room temperature emits infrared radiation, so
thermal imaging enables viewing of environments with or without
light. Warmer objects are clearly visible against cooler items when seen
through a thermal imaging camera. Several data sources are used based on
the surrounding environment for the camera to determine the approximate
temperature of specific objects.
A thermal imaging camera is typically similar to a camcorder. However, a
recording device is often not included, since live readings often show
temperature variations so plainly that further analysis is not required.
In the field of thermography, applications can be divided into passive and
active types. With passive applications, what the viewer is interested in is
naturally at a higher or lower temperature than that of the background. In
active thermography, the viewer uses an energy source to create a thermal
contrast between features of interest and the background.
Suspected H1N1 swine flu cases were detected using thermography by
airport and government officials during 2009. Thermal imaging can also be
applied in veterinary medicine and research, especially since it is a nondestructive test technique.
Thermal Imaging
Here's how thermal imaging works:
1. A special lens focuses the infrared light emitted by all of the objects in view.
2. The focused light is scanned by a phased array of infrared-detector elements. The
detector elements create a very detailed temperature pattern called a thermogram. It
only takes about one-thirtieth of a second for the detector array to obtain the
temperature information to make the thermogram. This information is obtained from
several thousand points in the field of view of the detector array.
3. The thermogram created by the detector elements is translated into electric impulses.
4. The impulses are sent to a signal-processing unit, a circuit board with a dedicated chip
that translates the information from the elements into data for the display.
5. The signal-processing unit sends the information to the display, where it appears as
various colors depending on the intensity of the infrared emission. The combination of
all the impulses from all of the elements creates the image.
image Enhancement
Image-enhancement technology is what most people think of when you talk about night
vision. In fact, image-enhancement systems are normally called night-vision
devices (NVDs). NVDs rely on a special tube, called an image-intensifier tube, to
collect and amplify infrared and visible light.
Here's how image enhancement works:
1. A conventional lens, called the objective lens, captures ambient light and some nearinfrared light.
2. The gathered light is sent to the image-intensifier tube. In most NVDs, the power supply
for the image-intensifier tube receives power from two N-Cell or two "AA" batteries. The
tube outputs a high voltage, about 5,000 volts, to the image-tube components.
3. The image-intensifier tube has a photocathode, which is used to convert the photons
of light energy into electrons.
4. As the electrons pass through the tube, similar electrons are released from atoms in the
tube, multiplying the original number of electrons by a factor of thousands through the
use of a microchannel plate (MCP) in the tube. An MCP is a tiny glass disc that has
millions of microscopic holes (microchannels) in it, made using fiber-optic technology.
The MCP is contained in a vacuum and has metal electrodes on either side of the disc.
Each channel is about 45 times longer than it is wide, and it works as an electron
multiplier. When the electrons from the photo cathode hit the first electrode of the MCP,
they are accelerated into the glass microchannels by the 5,000-V bursts being sent
between the electrode pair. As electrons pass through the microchannels, they cause
thousands of other electrons to be released in each channel using a process
called cascaded secondary emission. Basically, the original electrons collide with the
side of the channel, exciting atoms and causing other electrons to be released. These
new electrons also collide with other atoms, creating a chain reaction that results in
thousands of electrons leaving the channel where only a few entered. An interesting fact
is that the microchannels in the MCP are created at a slight angle (about a 5-degree to
8-degree bias) to encourage electron collisions and reduce both ion and direct-light
feedback from the phosphors on the output side.
5. At the end of the image-intensifier tube, the electrons hit a screen coated
with phosphors. These electrons maintain their position in relation to the channel they
passed through, which provides a perfect image since the electrons stay in the same
alignment as the original photons. The energy of the electrons causes the phosphors to
reach an excited state and release photons. These phosphors create the green image
on the screen that has come to characterize night vision.
6. The green phosphor image is viewed through another lens, called the ocular lens,
which allows you to magnify and focus the image. The NVD may be connected to an
electronic display, such as amonitor, or the image may be viewed directly through the
ocular lens.
Thermal Imaging System for SWINE FLU Detection
An early warning system to screen people in "real time", the High Resolution Fever
Alert infrared camera offers unmatched image sensitivity and clarity in a 320 x 240
radiometric imager. In less than a second it quickly and easily detects elevated body
temperatures and gives off both an AUDIBLE and VISUAL ALARM when a pre-defined
threshold is exceeded, indicating possible fever in humans. A Blackbody reference is
also used to regularly verify the accuracy of the imager.
This screening system can be used as part of a plan to minimize the spread of flu,
and potentially limit the infectious transmission of disease during an outbreak, in
both the workplace and public facilities
Features




Less than a second to take a temperature reading, thus no delay
processing people past the system.
Optimal response when screening narrow focused and at a short
distance.
Non-threatening - non-contact: Measures the temperature
coming off a surface and requires no contact with subject.
Blackbody verifies the accuracy of the imager.
Fever Alert System  the best choice as part of a prevention plan to detect Swine Flu.
Screen large groups of people, and possibly minimize the spread
of influenza in both the workplace and public venue's.
 Choose from hand held thermometers or cameras, to a high
resolution thermal imaging system.
 No delay processing people past the system
 Safe for subject and operator - No lasers
 Readout in °F or °C
 Automatically detects the highest temperature in an image and
alerts you with both AUDIBLE and VISUAL ALARMS
Can be used Effectively at:
Airports
Companies
Health Departments
Goverment Agencies
Public places
Irisys' infrared thermal imaging technology used to detect
Swine Flu
“Swine Flu” Background
A breakout of Swine Flu has been reported in Mexico and cases of Swine flu are also
now been reported globally. Swine flu causes fever with the body temperature rising to
greater than 100 F (38.0 C). Other symptoms may include headache, an overall feeling
of discomfort, and body aches.
In light of this various countries are considering or are deploying or carrying out trials
using infrared as a scanning technology to detect persons with elevated temperatures
which may be the result of Swine flu.
The purpose of such equipment is to:
1. Produce infrared or "heat pictures" of a human face by utilizing an infrared camera
and based on these thermal images provide surface temperature measurements.
2. Indicate if a user defined threshold temperature is exceeded. (Say 37 Deg C).
Note: that Surface skin temperature is lower than the internal body temperature.
The product that IRISYS are offering for such initial screening, (not a diagnostics tool) is
the IRI 2010. When a temperature in the scene exceeds the user defined threshold an
alarm is flashed up on the camera screen and an audible alarm sounded.
Additionally, the IRI2010 also incorporates a visual camera. This means that a person
with fever will not only be detected, but by use of the visual camera that person will also
be identified. This is particularly useful when screening groups of people.
Specifications
The key specifications are :1. Sensitivity - IRISYS 0.3 deg C
2. Accuracy of measurement - IRISYS Spec. is +/- 2 deg. C.
Improved Accuracy:
Improved accuracy system - The easy way to improve the accuracy of a temperature
measurement system is to have an external reference source in the field of view. The
imager can then measure the temperature of the reference source and a correction can
be made on the human body temperature. A check could be made on the reference
source every ½ hour or so.
Examples of various blends of thermal and visual pictures showing a person with a
temperature higher than the threshold set at 36°C.
An audible alarm is also sounded through the Camera Speaker.
100% Visual image 0% Thermal image
75% Visual image 25% Thermal image
50% Visual image 50% Thermal image
25% Visual image 75% Thermal image
0% Visual image 100% Thermal image
http://www.ametek-land.com/infrared/products/info/viralert-fever-screening-system?print=yes
http://www.weiku.com/products/3466478/Hand_Portable_Thermal_imaging_camera_for_H1N1_Flu_D
etection.html
working :
Thermal imagers are instruments that create pictures of heat rather than light. They measure radiated IR energy
and convert the data to corresponding maps of temperatures. Today, instruments provide temperature data at
each image pixel and, typically, cursors can be positioned to each point with the corresponding temperature read
out on the screen or display.
A special lens focuses the infrared light emitted by all of the objects in view.
The focused light is scanned by a phased array of infrared-detector elements. The detector elements create
a very detailed temperature pattern called a thermogram. It only takes about one-thirtieth of a second for
the detector array to obtain the temperature information to make the thermogram. This information is
obtained from several thousand points in the field of view of the detector array.
The thermogram created by the detector elements is translated into electric impulses.
The impulses are sent to a signal-processing unit, a circuit board with a dedicated chip that translates the
information from the elements into data for the display.
The signal-processing unit sends the information to the display, where it appears as various colors
depending on the intensity of the infrared emission. The combination of all the impulses from all of the
elements creates the image.
The process by which a thermal imaging camera transforms thermal energy into visible light consists of
five basic steps. These steps are:
 Utilize a specially designed lens to focus the infrared radiation that is given off from all
objects within the field of view of the camera lens.
 Infrared detectors are then used to scan this focused radiation. The detectors create what is
called a thermogram, or temperature map.
 The thermogram is then translated into electric impulses.
 The electric impulses are then sent to a signal-processing unit where they are translated into
data. The signal-processing unit is a tiny chip that is embedded on a circuit board, which is used
to translate the electric impulses into usable data.
 Once translated, the signal-processing unit sends the data to the display where it then becomes
visible to the viewer.
http://www.morovision.com/how_thermal_imaging_works.htm