Menu

Spectraline News

Frequently Asked Questions

WHY MID-INFRARED IS BETTER THAN NEAR-INFRARED?
Most materials have very strong bands in the mid-infrared region; since, radiation emanates from the fundamental bands, as opposed to weak radiation, in the near-infrared region emanating from what are called forbidden transitions.


IS THE WAVELENGTH RESOLUTION OF 21 NM SUFFICIENT?
The lead selenide detectors used in our instrument have excellent sensitivity in the mid-infrared (MIR) range (2.5 to 4.8 microns). For most materials, emissions in this range emanate from fundamental bands which are strong and spaced wide apart. This, translates to a very high signal to noise ratio, as well as, immunity to environmental radiation from factory lighting, sunlight, etc. which are mainly in the near-infrared (NIR) range (0.7 to 2.5 microns). Emissions in the NIR range emanate from overtones or transitions which are much weaker than the fundamental band emissions, and are also spaced very closely. Since the MIR bands are spaced much wider apart than the NIR bands, wavelength resolution of 21 nm is more than adequate to quantify various constituents in a sample.


WHY IS IT IMPORTANT TO HAVE SUCH HIGH SAMPLING RATES?
High sampling rates enable online monitoring of rapidly changing process variables. It is this capability that makes the ES-100 the first and only spectrometer that can be used for studying turbulent phenomena in real time.


IS IT POSSIBLE TO MEASURE MULTIPLE CONSTITUENTS AT THE SAME TIME?
The Spectraline instruments offer the highest speeds (up to 1320 Hz) available in infrared spectrometers or line scan cameras. This is a consequence of the fact that they were originally developed for NASA to study turbulent combustion phenomena. Currently available instruments can go no faster than 30 Hz and most of them require cooling to cryogenic temperatures. Spectraline instruments use a built-in thermoelectric cooler that requires no maintenance. Spectraline instruments are the only process-monitoring instruments that can quantify multiple constituents simultaneously and continuously in real time. This is a feature made possible by the use of advanced statistical deconvolution techniques that were developed for the first time.


WHY IS USER CALIBRATION NOT REQUIRED?
Spectraline instruments can be factory calibrated for the intended application using customer supplied samples of the material to be monitored. Variables such as environmental conditions and factory lighting do not affect the instrument.


WHAT IS THE DEPLOYMENT TIME OF THE INSTRUMENT?
We have developed a radically new method for deployment of the instrument. We collect samples of the substances to be monitored in advance, and determine the ideal wavelengths and method to obtain the best correlation between absorptance and concentration. This method, which is specific to the particular application, will be incorporated into the calibration module of the chemometrics software before shipping the product. The user is, therefore, not required to perform any calibrations and the instrument is ready to deploy upon unpacking. This is a huge advantage over NIR instruments; which typically require an extensive calibration effort of up to a year by the user before deployment to take care of variations caused by environmental conditions. NIR instrument makers do not get involved in this process which often proves to be a futile effort. This explains a recent industry survey finding; that over 70% of NIR spectrometers sold to industry for online monitoring applications, are in disuse and have not been deployed. The ES-200 can be deployed upon unpacking. All it needs is to be hooked up to a power supply and to a computer for data processing.


HOW RELIABLE IS THE INSTRUMENT?
The ES-100 was originally developed for NASA for micro-gravity research. In its first application, it was repeatedly dropped in a 2 km long mine shaft and performed flawlessly throughout. The ES-100 and ES-200 has no moving optical parts unlike conventional spectrometers that employ scanning mechanisms. It is also completely sealed against the environment and housed in a rugged metallic enclosure. The lead selenide array that is the detection element has an MTBF(Mean Time Between Failures) of 100,000 hours.


WHY IS CRYOGENIC COOLING NOT REQUIRED?
The ES-200 uses a PbSe array that has its own four stage thermoelectric cooler built in. The TEC cools down the array to minus 70 F at which the detector has an average D* value of 4 x 1010


WHY IS ALIGNMENT NOT REQUIRED?
Right from concept, the design intent was to produce an instrument that did not require any alignment on the part of the user. Optical design packages generated the precise locations of the optics and solid modeling using Pro/Engineer made possible the rapid optimization of the mechanical design. Solid models were also used to generate cutter location files for the CNC machining of the components to an accuracy of +/- 0.0005 in. The tight positional tolerances of the optics are maintained by rigidly pinning down all the optic holders. The net result of all this is an alignment free instrument that once it leaves the factory does not need any alignment in its lifetime.


IS THE INSTRUMENT PORTABLE?
Measuring 12" x 9.5" x 4.5", the ES-200 is the smallest mid-infrared imaging spectrometer in the market. The instrument is also light weight at 8 lbs and is very easily ported to any location.


CAN THE INSTRUMENT BE USED OUTSIDE THE LAB?
The instrument is completely sealed against moisture and contamination and can be used in the factory floor. Special versions of the instrument are also available for outdoor and explosion proof applications.


CAN THE ES-200 BE USED AS A BENCH TOP INSTRUMENT?
The ES-200 is a versatile instrument that can be used as a bench top spectrometer or in the adverse environment of a chemical production facility.


HOW IS THE SAMPLE INTERFACING DONE?
In the case of emission spectroscopy, the radiation entering the entrance slit of the instrument is imaged on to the detector array plane. In absorption spectroscopy, the radiation from a broad band source such as a tungsten filament lamp is passed through a precise thickness of the sample and then imaged on to the detector array plane. Liquid samples are passed through a flow cell attached to the front of the spectrometer. Alternately, a sampling probe can also be inserted into the flow and measurements made inline. In reflection spectroscopy, a radiation source is directed at a sample and the reflected radiation is imaged onto the detector array plane.