Pyrometer Series Metis MY80, MY81 and MY84 using pyroelectrical detectors and operating in a long wave band area between 8 and 14 µm. They were developed especially to measure small spot sizes at lower temperatures with fast exhibition times.
For none contact temperature measurement of thin polyester films and all kind of fluorocarbon-plastics the narrow band model Metis MY80 was developed.
Further more it is best choice to measure thin glass surfaces in furnaces because glass is neither transparent nor reflective at 8,05 µm. It meets therefore the so called black body conditions of an ideal radiator.
The infrared energy radiated by the target is centered via focusable or fixed focus lenses directly on the detector. The focusing feature allows control of the cone of vision and offers the possibility to measure either a small spot (focused) or the average of a bigger spot (out of focus). Fixed focus lenses with larger diameter collect more infrared energy and therefore result in smaller spot sizes.
The lenses are made of calcium fluoride CaF2 (MY80 and MY81) or zinc sulphide ZnS (MY84). If additional windows are necessary they must offer similar optical characteristics. The detector is sensitive to infrared radiation in an area called the cone of vision. For the spot size diameter of the cone of vision at shortest, medium and widest focal distance. For full scale temperatures up to 700°C the cone of vision diameter in front of the lens is about 16 mm and about 8 mm for full scale temperature of 1000°C. This area has to be kept free from any intervening objects.
The spot size diameter for distances not given in the chart can be calculated by interpolation. Each temperature range of MY81 and MY84 are available as well with different fast exposition times of 5, 30, or 100 ms. Slower models offer better optical resolution (smaller spot size). To achieve effectively the best optical resolution of 170:1, with 100ms exhibition time, the Metis MY81 can be supplied with fixed focus lenses also. For the spot size diameter of the 3 different fixed focus lenses available with MY81 ser.
Metis MY Pyrometers are available with 2 different solutions for aiming the sensor onto the target. The first and most popular method is the built-in laser pointer which is also helpful for focusing. The second solution is a sight through optics version with reticle-defined target which is advantageous for applications like measurement into furnaces where the laser is not visible from the outside of the furnace.
Temperature Output Signals
Metis Pyrometers offer a variety of analog and digital output signals for displaying, recording, archiving and controlling of measured process temperatures. The isolated analog output is selectable from 0 to 4 - 20 mA. Zero- and full-scale temperatures are adjustable to cover any portion of the instrument’s available temperature span to a minimum of 50°C. There is a choice of 2 digital communication interfaces: RS 232 or RS 485 max. 19.2 kBd.
For measuring and holding of the highest instantaneous temperature value a peak picker (maximum value storage) is installed to compensate interruptions or attenuations in radiation caused by bursts of steam, smoke or dust. It can be reset either automatically or manually by an external contact closure or periodically by user preset clear time. In the last case the highest temperature will be held in a dual storage and will be reset in only one of the two storages after preset clear time to avoid a decrease of the temperature output, should a short cold period appear just at the reset moment. The exposition time is the length of time it takes for the output signal to reach 90% of a step change in measured temperature. It can be used to filter out rapid variations in temperature and achieve a “more quiet” signal for control or display purposes.
The PSCWin Software is available for automatic or manual set up of the pyrometer, for recording and for saving of graphical or table files. At the same time these files can be used for quality assurance purposes because the parameter settings are recorded, too. Minimum computer requirements: 500 MHz clock frequency and Windows 95, 98, ME or XP operating system.