Friday, 10 February 2012

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WG320 IR Fever Detection Camera

Keeping the spread of viral infections under control

Infrared thermography helps to detect and contain the spreading of influenza and other viral diseases.

Growing international exchange, travel, and economic migration require a consistent, prompt, effective and international viral disease prevention policy.

Elevated human body temperature, or fever, is a convincing and reliable indicator of most human viral infections. Following recent outbreaks of pandemic influenza, public health authorities around the world have been looking for a fast, easy, contactless and reliable method to detect elevated human body temperature differences.

Thermography is such a method. It has become vital to control body temperature of risk groups such as travellers and proven itself as a monitoring tool that has substantially contributed to reduce the spreading of influenza virus in many countries and regions of the world.

Fever detection camera, picture

An infrared camera is a very effective tool to detect people infected with a viral disease at a very early stage. It produces thermal images or heat pictures which allow it to display even the smallest temperature differences.

Human body temperature is a complex phenomenon, humans are homeothermic, they radiate heat, which must be lost to the environment the interface between that heat production and the environment is the skin.

This dynamic organ is constantly adjusting the optimum balance between the physiologic demands of the body and external environmental conditions.

Infrared thermography provides a visual map of skin temperatures in real time; in addition, infrared cameras are very sensitive devices. WG320 cameras can measure temperature differences as small as 0.08 ºC.

The symptoms of most infectious diseases are similar - malaise, sore throat, coughs and of course fever. Consequently, it is extremely easy to detect whether a person carries the risk of having an infectious disease or not.

All that needs to be done is make an infrared image of the subject and measure if his/her body temperature exceeds a certain value.

The WG320 infrared camera's built-in functions colour and sound alarms can be set to go off when a certain temperature threshold is being exceeded, the operator can instantly decide whether the subject needs to be referred for medical examination or not. As the infrared camera produces images in real time, the total evaluation process takes less than a second.

Fever Screening Comparison

A person's general skin temperature is not equal to the person's core temperature.

The most practical spot on the body giving the most reliable result (where the skin temperature approaches the core temperature of the human body) is in the corner of the eyes where the lachrymal duct comes to the surface.

It is therefore recommended to take subjects in front of the camera at a marked distance, in general at 1 to 1.6 metres away from the camera lens, so that the face fills the entire image, the subject only needs to look into the camera for less than a second.

As the highest temperature will be measured in the corner of the eyes, people can continue to wear a mouth mask or their headwear without influencing the measurement.

Glass and plastic do not transmit infrared radiation, so people need to remove their glasses in order to be examined.

It is advisable to set up the infrared camera at places with long queues such as passport or customs control points as persons should be screened on an individual basis. It is also recommended, though not mandatory, to install the camera on a tripod and connect it to a video screen, to facilitate the working conditions of the camera operator.

It is not necessary to measure absolute temperatures to determine whether a person has an elevated temperature or not.

The following procedure has been initially followed to determine if infrared measurement works: after measuring the true body temperature of approximately 10 to 25 healthy people with a medical ear thermometer and the face temperature of these same people with a WG320 infrared camera, the average temperature difference is calculated: true body temperature minus face temperature.

Experience has shown that this average temperature difference is fairly constant and varies between 0.8 and 1.2°C depending on the environmental conditions of the test area, such as ambient temperature, air conditioning, wind, weather conditions etc.

This corresponds to the principle that the body temperature of a feverish person is about 1°C higher compared to a healthy person. Whether that average temperature turns out to be 32, 34, or 36°C is not relevant. It should be correlated to the core temperature and remain stable.

In practice, the camera is installed and can be used immediately: the infrared camera automatically calculates the average temperature of the first 10 scanned people and then defines their average. Then, an alarm should be set to go off when the measured temperature reaches an average plus 1°C.

The purpose is to differentiate the people who are well from those that have fever and not to measure absolute body temperatures. The absolute error measured on both the threshold values and the subjects tested will be the same, as long as the camera is stable.

Automatic Temperature Compensator (ATC)

The WG320 infrared cameras is equipped with an Automatic Temperature
Compensator (ATC) to avoid generating false alarms.

The ATC constantly calculates a moving average of the body temperatures from the last 10 scanned people. The two highest and the two lowest values are not taken into account when making this calculation.

Based on the outcome of this calculation the ATC automatically adjusts the generation of visible and audible alarms, greatly improving the reliability of the screening.

Set Up Operation

There should be no hot objects such as lamps in the field of view of the camera;
The camera should be turned on at least 30 minutes before measurement starts and carefully focused;
Set the emissivity value to 0.98;
Determine the average temperature of a healthy person by using an ear thermometer and an infrared camera (or utilise the built in ATC function);
Add 1°C to the average temperature of a healthy person to obtain the critical temperature;
Set an area in the infrared camera;
Set the colour and sound alarms to signal if the temperature within the area is higher than the critical temperature;
Bring the subjects to be tested, one by one, in front of the camera, Each for about 1 second;
If the alarms signal, detour the subject for further examination.

Key features

Built-in extensive analyses function: Spot, area measurement and difference function;
Built-in alarm function: As function of analyses, internal temperature or digital Input;
Power over Ethernet: Communication and power supplied with only one cable;
Messaging functionality: The camera automatically sends analysis results, IR images and more as an e-mail on schedule or at alarm. Autonomous dispatch of files or e-mails, acting as an FTP- or SMTP-client;
Image masking functionality: Select only the relevant part of the image for your Analyses;
MPEG-4 streamed video: MPEG-4 streamed video output over Ethernet to show live images on a PC, 640x480 with overlay at up to 30 Hz;
IR monitor software: In house developed software with support to up to nine cameras simultaneously;
Digital inputs/outputs: For alarms and control of external equipment;
16 bit image: 16 bit image transfer to PC for analyses;
Remote control: Remote control of the camera over the Web and TCP/IP protocol;
Video output: Composite Video output, PAL and NTSC compatible;
Lens: Built-in 25 degree lens with both motorized focus and autofocus;
High sensitivity < 50 mK: For clearer images;
320x240 pixels: Excellent image quality;
Compact & lightweight design.

Measurement Analysis

Analysis

4 Spotmeters;
4 Areas (Box, max/min/average/position);
Isotherm (above, below, interval);
Reference temperature;
Temperature Difference (between measurement functions Reference temperature);
Measurement Mask Filter.

Schedule response

File sending (ftp);
email (SMTP).

Measurement corrections

Global and individual object parameters.

Alarm functions

6 automatic alarms on any selected measurement function, Digital In, Camera temperature function.

Responses

Digital Out, log, store image, file sending (ftp), email (SMTP), notification.

Ethernet

Ethernet, purpose: Control, result and image;
Ethernet, type: 100 Mbps;
Ethernet, standard: IEEE 802.3;
Ethernet, connector type: RJ-45;
Ethernet, communication: TCP/IP socket-based;
Ethernet, video streaming: MPEG-4, ISO/IEC 14496-1 MPEG-4 ASP@L5;
Ethernet, power: Power over Ethernet, PoE IEEE 802.3af class 0;
Ethernet, image streaming: 16-bit 320 x 240 pixels
- Signal linear
- Temperature linear
- Radiometric
Ethernet, protocols: TCP, UDP, SNTP, RTSP, RTP, HTTP, ICMP, IGMP, ftp, SMTP, SMB (CIFS), DHCP, MDNS (Bonjour), uPnP.

Digital Input/Output

Digital input: 2 opto-isolated, 10-30 VDC;
Digital input, purpose: Image tag (start/stop/general); Input ext. device (programmatically read);
Digital output: 2 opto-isolated, 10-30 VDC, max 100 mA;
Digital output, purpose: As function of alarm, output to ext. device (programmatically set);
Digital I/O, isolation voltage: 500 VRMS;
Digital I/O, supply voltage: 12/24 VDC, max 200 mA;
Digital I/O, connector type: 6-pole jackable screw terminal.

Composite video

Video, purpose: Composite video output, PAL and NTSC compatible;
Video, connector type: Standard BNC connector.

Imaging and optical data

Field of view (FOV): Built-in 25° x 19°;
Close focus limit: 0.4 m (1.31 ft.);
Focal length: 18 mm (0.7 in.);
Spatial resolution (IFOV): 1.36 mrad;
Lens identification: Automatic;
F-number: 1.3;
Thermal sensitivity/NETD: 50 mK @ +30 °C (+86 °F);
Image frequency: Up to 30 Hz, image stream and system dependent;
Focus: Automatic or manual (built in motor);
Electronic zoom: 1-8x continuous, interpolating zooming on images.

Detector data

Detector type: Focal Plane Array (FPA), un-cooled microbolometer;
Spectral range: 7.5-13 μm;
Resolution: 320 x 240 pixels;
Detector pitch: 25 μm;
Detector time constant: Typical 12 ms.

Measurement

Object temperature range: -20 °C to +120 °C (-4 °F to +248 °F), 0 °C to +350 °C (32 °F to +662 °F), optional 250 °C to +1200 °C (482 °F to 2192 °F);
Accuracy: ±2 °C (±3.6 °F) or ±2% of reading.

Power system

External power operation: 12/24 VDC, 24 W absolute max;
External power, connector type: 2-pole jackable screw terminal;
Voltage Allowed range: 10-30 VDC.

Environmental data

Operating temperature range: -15 °C to +50 °C (+5 °F to +122 °F)
Storage temperature range: -40 °C to +70 °C (-40 °F to +158 °F)
Humidity (operating and storage): IEC 60068-2-30/24 h 95% relative humidity +25 °C to +40 °C (+77 °F to +104 °F);
EMC: EN 61000-6-2:2001 (Immunity), EN 61000-6-3:2001 (Emission), FCC 47 CFR Part 15; Class B (Emission);
Encapsulation: IP 40 (IEC 60529);
Bump: 25 g (IEC 60068-2-29);
Vibration: 2 g (IEC 60068-2-6).