ASI RAMM Microsocpe Testing

Over the past few years, ASI has cooked up a modular microscope. The design was for an optical bench that would support a wide range of configurations, as well as rapid adaptation and expansion. The system relies on conventional lenses, thus you can use any high quality Leica, Zeiss Nikon or Olympus objective. Just attach the appropriate nosepiece and tube lens, provide an objective, and image away. Of course the first thing one might wonder with a system like this is, how well does it perform? As a complete opto-imaging geek, I’ve been drooling over the opportunity to get my hands on one of these rigs. Luckily, ASI allowed me to borrow one. I decided to build up a complete fluorescent package, in order to truly characterize the system’s performance. Here’s what I found:

System Configuration

I built my RAMM variant around the following components:

• RAMM Scope Body with transmitted illuminator.
• Nikon Standard Tube Lens
• Nikon CFI 60 Plan Apo 60x VC 1.4NA Oil Lens
• Chroma Filter Set (Old non-ET set – just what I had handy)
• ASI MS-2000 XYZ Stage and focus block
• ASI CRISP attachment (Not reviewed here)
• Andor Clara Camera
• Lumencor Spectra X Engine
• MicroManager and NIS Elements Software

Design

The RAMM is built like a skeleton structure, and looks completely foreign compared to the “normal microscope”. There are attach points drilled all over the body of the stand. I’m assuming some of this is to lighten the body, and also to provide mounting points for new as-yet unknown applications in the future. The entire stand is machined from billet aluminum, and class 2 anodized in black. The different components that make up the base are totally modular.

For instance, you can mount the optical system to the top, the bottom, left side or right side of the stand, as may be needed for fit or for custom applications. There is a provision to stack optical paths in the infinity space behind the lens, which allows for the addition of multiple illuminators, or the attachment of additional cameras, CRISP auto-focusing modules, etc. I could also imagine using this port for delivering home-brew laser light, or delivering light from a micropoint or mosaic style of system.

Testing

Considering that this design is relying on well-characterized optics, I was interested in testing what, if any, errors were introduced by this stand.  My first test sample was a Molecular Probes stained kidney section. Z stacks were acquired at 2um spacing with the camera set to full resolution. Results were as expected. Z section images, projections, and 3 dimensional renderings looked as they do on a conventional scope.

My next sample was much more rigorous. I have a 100nm Tetra-speck bead slide that’s about 10 years old. This meant the fluorescent signal would be very low, but I wanted to acquire some bead stacks to look at basic aberrations or other errors. After taking 20nm sections, I was able to get the following results.

Image Stack from RAMM Scope from austin blanco on Vimeo.

This example shows a nice barely resolvable bead, looking as it should.

A better representation of a small bead is to view the PSF. Here’s an XY, XZ, YZ Ortho projection showing all 3 sides of the stack. This is a good PSF, as no skew, coma or aberrations are visible. The bead simply looks like an egg. This image is very low signal to noise, so a more robust test is needed to fully characterize the optical system, but in the short term, this shows excellent optical performance for a diffraction limited spot.

Next I tested stage flatness, with no major problems found across the travel of the stage. Small variations in leveling can be corrected using the insert adjustment screws if needed, which is the same for traditional microscopes.

Software Integration

Getting the system configured for use in any software package is rather straightforward, as NIS Elements, and Micro-Manager both support ASI products. Current versions of Micro-Manager have a bug with the Spectra X (all other models are supported though), so in order to test my system I used elements. Both packages run the Andor Clara, as well as most other third party products. I can imagine using this scope for anything from a basic multi-d timelapse rig (building a chamber for this would be cake!) to using it as a spinning disk platform. MetaMorph software would be another great driver for the scope, as Meta is brand-free, and is extremely fast. I’m not sure if all packages have added ASI’s Transmitted LED control yet, but in the worst case one could manually control the brightness, and use the ASI ttl to control the shuttering, providing a low cost and effective transmitted light option.

Limitations

Current limitations include a lack of motorized objective turret for Nikon lenses, (Olympus nosepieces are available) a lack of a multi-position dichroic, and a lack of DIC capability in the design (not to say that DIC isn’t possible, just not “built in”). Of course, the user has to be comfortable running an instrument like this without oculars, but I might be able to convince the most stubborn eye-ball happy microscopist to avoid this if we surveyed how many core facility managers wear glasses…

Advantages

I see several unique and major advantages that one may consider when looking at how a system like this fits into the microscope market:

• The open architecture frame supports all lenses, so you can simply use lenses from your current, maybe outdated or no longer needed scope, without having to invest in a whole new optical line. It also means that users who wish to modify, hack or expand an instrument like this can obtain information from a local company, without having to chew through several layers of red tape. This to me is a major advantage when compared to a traditional big 4 scope.
• The fear of getting stuck with one set of glass is removed. Currently if you invest in a Nikon system, or Zeiss or any other, there is a tendency to keep using that brand, due to the common glass. This system removes that limitation, allowing users to purchase the best objective available, not the best objective for a specific brand.
• The modularity of the instrument translates into major growth potential, as well as refitting for emerging technologies. One could use this initially as a multi-well timelapse scope, them convert it into a TIRF system later on. You can even convert this into an upright!
• The cost of this instrument, when outfitted for motorized acquisition, is $10-20k lower than competing products. This is a compelling point considering how we all have to do more with less these days.
• This instrument occupies 30-50% of the footprint space when compared to traditional inverts. Bench space is always a precious thing in the lab, and this system takes up little. Not only is the width and height less of a problem, but the most common obstacle, the length, is a complete non-issue. The body stands roughly 1.5’x1.5′ in size. consider a typical inverted microscope is something like 2.5′ long! This opens up a new realm of places to stash the scope, saving bench space for the hard science.

Conclusions

I’m very intrigued by this instrument. I think it may have come along at just the right time. Researchers are now realizing that the current product offerings limit the potential for new technologies. Why buy the next model scope, when you can simply expand a well designed system? It’s also a refreshing thought that I can call up ASI, and get all the information I need to leverage this system’s capability. Try that with emailing to Germany or Japan. As budgets tighten, labs need to have more flexible tools. This system provides just that. Of course there will always be a need for a “standard scope”, but for high end, custom applications, this microscope provides a compelling option when compared to the restricted access one must accept when buying a traditional stand. Is our community  ready for next-gen optical platforms? Only the future will tell…