Contactless Temperature Measurement Research Articles

Multispectral infrared pyrometer for temperature measurement with automatic correction of the influence of emissivity

A new method for contactless temperature measurement has been developed. (1) It is applied advantageously to highly reflecting objects of moderate temperatures (emitting no visible radiation), where conventional methods fail. A set of data is collected by radiance measurement m a number of n narrow spectral bands. These data represent numerical values for a set of analytical equations of the radiation emerging from the object. Solving the set of equations leads to u ⩽ n unknowns, which are the temperature of the object, its emissivity and the temperature of its environment. Balancing calculation enhances the accuracy. Software simulations, including the balancing calculation, the radiation transfer and the hardware of the prospected multispectral radiometer optimized the whole system prior to hardware development. The finally assembled laboratory model, a ten channel filter spectrometer, proved to function as predicted. The temperature of objects about 500 K and an emissivity as low as 0.03 has been determined with less than 1% deviation from thermocouple measurement. Measurement at lower temperatures and/or higher emissivities or higher temperatures and/or lower emissivities is possible with comparable accuracy.

Variability of the thermal behavior of honeybees on a feeding place

The thermoregulation of honeybees (Apis mellifera carnica) was investigated under field conditions, on a feeding place 335 m away from the hive, where 0.25M or 0.5M sucrose solution was offered. By means of real-time tele-thermography, contactless body surface temperature measurements of undisturbed animals were made. The foraging bees showed highly developed individual thermoregulatory abilities. Complex behavioral patterns such as food uptake, active body temperature regulation, and preparation for flight were performed simultaneously. However, body temperature was more variable than expected. When bees drank 0.5M sucrose solution, they generally had a higher thoracic surface temperature (T Ths) and showed smaller temperature fluctuations (e.g., cooling down after landing) than with 0.25M solution. Given 0.5M sucrose they stayed for shorter periods at the feeding place. The highest (maximum)T Ths during the stop was positively (linearly) correlated with the ambient temperature (T a=18−30°C) for both 0.25M and 0.5M sucrose feeding. At aT a of 19°C the mean (interpolated) maximum values forT Ths were 37.2°C (0.25M) and 38.5°C (0.5M); at aT a of 27°C they were 39.2°C (0.25M) and 40.9°C (0.5M). The minimumT Ths was correlated withT a only with 0.5M feeding, whereas with 0.25M feeding a great variability was observed. Similarly as the maximumT Ths,T Ths upon landing and taking off were positively (linearly) correlated withT a and were higher during 0.5M feeding. The quality (concentration) of the food offered to the bees obviously influenced their thermal behavior at the feeding place.

Contactless temperature measurement of the heart

In open-heart surgery, hypothermia and cardioplegia are used for the protection of the myocardial tissue. The risk of operation is reduced by a favourable course of cooling and rewarming of the heart. The object of investigation was the experimental and clinical testing of methods of contact and contactless measurement of the heart muscle temperature. The infrared temperature measurement has essential advantages. The construction, function and abridged specifications of infrared pyrometers developed for surgery are discussed.

Contactless surface temperature measurement with a reflecting screen

Contactless surface temperature measurement with a reflecting screen

Scanning device for contactless measurement of temperature

Structural nonuniformity and various defects in inspected materials and products result from a nonuniform distribution of heat flows inside the solid, which in turn leads to the development of temperature gradients on the surface. The heat required for this process may either be liberated during operation of the product or may be supplied by an external force. Recording the resulting thermal gradients, which often amount to fractions of a degree, is a fairly complex problem. However, a knowledge of the distribution of temperature over the surface of a product would allow us to solve problems of flaw detection and operational control.