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A True Breakthrough for Optical Spectroscopists!
The “DeSa Subtractive Double Grating Monochromator with Moving Intermediate Slit” is a unique technology and patented F/4.4 monochromator which we use in absorbance, fluorescence, CD, and LD spectrophotometers.
Because the monochromator is a “rapid-scanning monochromator,” we refer to it as an “RSM.”
Because the spectrophotometers we build around it support acquisition of “1000 scans per second” or “1000 data points per millisecond,” we follow “RSM” with “1000.”
The “1000 scans per second” is more commonly used during stopped-flow and other submillisecond rate studies.
The “1000 data points per millisecond” is used in both laser/flash photolysis rate studies where all of the data must be collected in microseconds or slower; and, paradoxically, in slow scanning work. That is, when the RSM 1000 is scanning like an ordinary monochromator, it is actually collecting and averaging data in a dual beam 1 MHz mode. Hence, its ability to collect noise in the fifth decimal place in seconds.
As of the summer of 2005, a 20 MHz speed version will be available, supporting collection of up to 20,000 points per millisecond!
Click here for a pictorial comparison of the RSM in five popular configurations.
All Olis RSM 1000 configurations feature exceedingly low stray light, high photometric accuracy, photometric precision, and other superb optical characteristics.
Millisecond scanning is not done by moving the gratings, as it done with traditional scanning instruments. Instead, to achieve 230,000 nm per second, the Olis RSM 1000 utilizes a moving intermediate slit wheel. This simple 'spinning intermediate slit disk' technology was awarded a US Patent and an R&D 100 award in 1994.
The RSM utilizes photomultiplier tubes (PMTs) for the UV/Visible range and InGaAs detectors in the NIR. PMTs are the most sensitive and fast detectors available and are usable over wide wavelength ranges and over wide dynamic ranges.
The Olis RSM 1000 does not include a diode array detector or CCD.
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The PMT based RSM is:
Photometrically Accurate.
It rejects stray light, takes dark readings thousands of times a second, and is a dual beam (sample/reference) design.
Suitable for Measuring (even highly) Turbid Samples.
This is possible because we position the PMTs 10 mm more or less as you need from the sample and reference cuvettes.
Sensitive enough to make millisecond spectral scans of luminescence signals such as fluorescence and bioluminescence spectra.
Will Not Cause Undesirable Photolysis of Photoliable Samples.
Modest intensity monochromatic light illuminates the sample; white light could be blasted on your sample to induce a photolytic change, but only when you want it to.
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The rapid-scanning monochromator is a double grating system for stray light rejection (< 0.0001%) and true spectra acquisition (not difference spectra). As a subtractive double grating design, it provides a homogeneous output beam.
The Olis RSM is designed for maximum flexibility and modularity; the hardware and software can be optimized for each experiment. For instance, you can change optical ranges covered in each millisecond scan, you can fine-tune resolution, you can add a stopped-flow mixing system, or a photolysis apparatus, or do temperature dependent studies, all with obvious and easy hardware changes.
Fixed wavelength fluorescence or luminescence measurements can be made with the 'standard' absorbance model. And, after the addition of a brighter excitation source and a sister (excitation) monochromator, 1,000 emission scans per second can be captured.
The mathematics for 2D and 3D analysis provide you with instantaneous fitting of spectra and kinetics. Our use of robust fitting rather than least squares fitting is correct. Our use of factor analysis is correct and 1300 fold faster than the published algorithm. (Fits on 1,000 spectral scans take one or two seconds to complete.)
Of course, what really matters are results. Three weeks after receiving his Olis RSM 1000 plus U.S.A. Stopped Flow, Prof Grant Mauk of the University of British Columbia wrote "We have one experiment produced by the RSM that will be included in a poster to be shown at [the 7th International Congress of Bioinorganic Chemistry]." That's results. Fast!
By the way, if you don't see exactly what you need here, just ask! We routinely customize. View two unique configurations of the RSM in Utah and Illinois.
What does 1000 scans per second look like?
View a dynamic simulation of the light throughput of the RSM.
The RSM 1000 vs. Diode Array Systems.
46 points on the uniqueness of the RSM 1000.
View the RSM fitted with a Biologic stopped-flow.
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