A comparison of the Cary Eclipse™ Fluorimeter
with the OLIS DM 45
The Varian Eclipse is quite a bit lower in quality, using lesser optics, a pulsed xenon arc lamp, and ‘appliance-specific’ software.
Optics: the monochromators
The Eclipse includes a “Monk-Gillieson” monochromator. Do you know what this is? We didn’t. So, we looked it up and learned “For low-resolution applications, the Monk-Gillieson mount enjoys a certain amount of popularity, since it represents the simplest and least expensive spectrometric system imaginable.”
While this Monk-Gillieson monochromator is handsomely displayed on the Eclipse brochure, seeing it is as worrisome as reading about it: there are many components which will fail in time.
Compare this with the single 45 x 40 mm grating inside of an OLIS DM 45 monochromator which moves with a computer controlled mini-sine bar assembly and the 40 mm square mirror cemented into a fixed position.
Our optical bench has a much higher likelihood of reliable performance for the decades ahead.
Excitation Source: The lamps
They use a pulsed lamp; we use a steady-state lamp.
Varian explains the pulse lamp as “to avoid photobleaching” that it is a “long-lived excitation source,” and, that they have implemented a “newly designed reference signal system … to provide users with much more control over signal dynamics.”
We suggest that the actual reason for using a pulse lamp is that the Monk-Gillieson optics are so insensitive that a steady-state source could not be used successfully.
And, the variability in intensity between flashes of a pulsed source can be very significant, so that data can only trusted is if a reference channel is used.
Along this line, they refer to “corrected spectra.” They are correcting their results against the lamp intensity, but they are not making an absolute correction in the text book sense.
Software: Very simple vs Very comprehensive
The Eclipse is designed to be a simple application device which will be replaced in 2-5 years.
The OLIS DM 45 is built for reliable use for decades and to be upgraded when its user interface is obsolete. As a client with 15+ years experience noted long ago: “You guys make investment spectrophotometers!” Our software’s quality matches the hardware’s.
Points against the Olis DM 45 are
We do not offer a multiplate reader
The OLIS DM 45 is larger than the little Eclipse.
The cost of the “investment spectrometer” is higher than the cheap appliance.
A comparison of the Horiba Duetta
with the OLIS DM 45
The Horiba Duetta: A very-low priced mass-produced appliance designed to be
useful enough for basic applications including using Rhodamine B and
Rhodamine 6G) and affordable to many.
In more detail:
1. A CCD detector will be several orders of magnitude less sensitive
than a photon counting detector. One would never choose a CCD as the
preferred detector if the goal were sensitivity, only if the goal is fast
and cheap.
2. It might collect a spectrum in "less than one second," but
successfully only from very brightly emitting samples; otherwise, much
longer acquisition times will be needed.
3. The xenon arc must be a pulsed xenon, so its reproducibility will be
low
4. Speed is limited by the CCD and pulse lamp, so acquisition rates to
subseconds, milliseconds, or microseconds are not be possible
5. It's an entirely sealed instrument, so to the student, it's just a
beige container she puts a cuvette it. There are zero pedagogical
opportunities for discussing, touching, seeing the light source, excitation
monochromator, emission monochromator, detector, etc.
6. As such, there is no opportunity for optimizing this appliance for
different conditions. It is what it is, with zero upgrade or customization
potential.
7. As such, diagnosis and repair is a mystery to all other than
corporate trained technical staff; the academic lab members will not be able
to do any work on the equipment themselves.
8. The Duetta is a poster child for designed-in obsolescence.
9. They call it a "a true 3-in-1 instrument," but they are calling
absorbance and transmission two different measurements, when they are the
same data presented on different scales.
10. They state "Data acquisition is more accurate because measurements
are taken from the same spot without moving the sample and repeating the
exercise." Can anyone explain what this means?
In summary, it's perfectly fine for an environment where cheap, simple,
limited are prioritized. A research lab or a competitive pedagogical lab
would be quickly disappointed with its limitations.
Advantages of the OLIS DM 45:
1. Orders of magnitude higher sensitivity with the exquisitely sensitive Hamamatsu photon counting detector
2. Near total freedom to select data acquisition rates appropriate to a
nearly limitless array of experiments
3. A much more pedagogically rich experience for the student and
teacher visually, mechanically, and optically
4. Encourages owner optimization, diagnostics, upgrades, repairs,
modernizations
5. Accommodates far more accessories, from polarizers for anisotropy to
a stopped-flow for rapid chemical denaturation work
6. Software supports scanning the two monochromators in synchrony, so
that the wavelengths are matched, i.e., one is using this spectrofluorimeter
to collect absorbance (or transmission) data.
7. With a modestly priced enhancement, the instrument can acquire
phosphorescence lifetime
8. Excitation could be enhanced with use of steady-state or computer
controlled LEDs for brighter excitation and pulse photolysis experiments
9. Vastly more useful software for data collection and data analysis,
with single keystroke exporting into Excel
10. Upgradable in era as well as application: when the original
computerization becomes outdated, it can be replaced with a newer computer;
when the original electronics become outdated, they can be replaced with
modern ones.
11. Produced and supported by a private-held American woman-owned
business, founded in the 1970s by a research biochemist
12. Hand-crafted of highest value components for outstanding performance
today and heirloom status in the decades ahead
13. Easy to use
14. Easy to maintain
15. No consumables to buy
16. Excellent technical support
17. A stopping point on the tour of the laboratory embodying quality,
longevity, value