Spectrometers, spectrophotometers, photometers, colorimeters, fluorometer, reflectometers, radiometers, densitometers, nefelometers, luminometers, oxymeters, Raman.
How to choose suitable spectrometer?
10 Basic questions and answers
This subject will be suitable for every of you decided to buy spectrometer or analyzer.
What to look for by choice
1. Detector Arrays (the heart of the spectrometer). The newest detectors for UV-VIS-SWNIR range are CCD (Charged Couple Device), CMOS (complimentary metal-oxide semiconductor) PDA (photodiode array) and older NĚOS (Negative-channel metal-oxide semiconductor) and InGaAs (Indium gallium arsenide).
2. Ask for the producer.
Who are leading producers - Hamamatsu, Toshiba, Sony
3. Ask for the number of pixels.
Every detector is compound from definite number of pixels, as many – so many better. The resolution depends on the slit and the diffraction grating and reaches 0.01 nm
For example „Specol 11“ has 1 diode (pixel) with rotating diffraction grating by reaching to definite nm. For example, buying Toshiba 3648 means that you buy 3648 Specols.
4. What to look anything for except the number of pixels and also their size-as much bigger as much better – bigger sensitivity. For example Toshiba 3648 has height 200 um x 8 um width, 200 um will detect more information than the pixels with smaller height and it provides pixel well depth 100 000 electrons.
5. Main indicator for stability is the ratio Signal/Noise of the detector, as much bigger as much better. For example Toshiba 3648, Signal/Noise 300:1, Hamamatsu 256 S/N 4000:1
We talk about the detector and not for software improvement of the spectrometer.
6. Integration time of the detector – as much smaller as much better. The minimum time for integration is between 300 microseconds to 10 milliseconds.
7. The speed of scanning of the spectrometer from 100 to 700 scans of the entire spectrum for 1 second.
8. Analog to digital converter. They are 10, 12, 14, 16.... bits, they are chosen from the purpose of the spectrometer.
9. Interface – USB is good choice.
10. Software – for Windows, multifunctional.
We know that we haven't finished the subject. For those who are interested we can offer additional information on considered questions but it will help for basic reference point in the market for offering.
Introduction to optical bench
It has a lot of kinds optical benches but the classical one is Czerny-Turner. They are symmetrical and asymmetrical. The advantages of symmetrical is that it projects the same size of the slit on the sensor. When benches are asymmetrical, there is a lack of information, in view of the fact that the sensor is not in the exact focus distance and for not losing information most manufacturers place additional lens. Since we know that all optical lenses has some kind of aberations and exactly placed this lens on the sensor it can give deviation in analysis at precise measurements. The same disadvantage has at shorter benches, because it is used cut mirrors and a part from information of the slit is outside of the mirror.
Orpheus Optics uses full mirrors, in order to be able the entire image on slit to fall into the mirror, as also full symmetrical benches with optimal sizes for every sensor.
The spectrometers Orpheus Optics covers the following fields: in high effective analytic and laboratory spectrometric researches in the field of chemistry, physics, biology, astronomy, archeology, biomedical spectrometric analysis, spectrometric ecologic monitoring, spectrometric control on quality of the raw material and the ready production.
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