Re: **Commercial Response**Spinning disk comparison - CSU-X1 vs CrestOptics X-Light V3

[WILDE Geraint]

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Dear Will,
As some of the responses so far have indicated, there are variety of variables in design that will impact performance here.  Personally, I think the techs from “a large microscope company” were too sweeping in their statement, unless there is more to the context of the exchange you had with them?  Given the forum and wanting to respectfully follow the rules for commercial responses I will comment in as balanced a way as I can.

Disk designs without microlenses with, let’s say, 50um pinhole and 250um spacing gives you about a 4% pinhole transmission (~96% excitation light has to be rejected).  Microlens-free designs can overcome this using two or more of the following approaches:
1. have a high density of pinholes to either overcome their lower excitation transmission efficiency, and/or to be able to capture at exceptionally high frame rates for extreme cell dynamins like calcium sparks and puffs.  
2. Have larger pinholes.
3. Simply use higher power lasers.
4. Instead of using single mode fibers, as is the case for CSU, use multimode fibres.

Limitation of (1) is lower blocking of out-of-focus light and so higher background in multicell thick cultures or thicker (e.g. tissue and model organisms).  So depends on your needs
May also mean higher light intensity for running at such high-speeds therefore optimal for shorter term imaging (due to phototoxicity).
Limitation of (2) will be on resolution, but the importance of this also depends on your needs.

Microlenses can improve excitation throughput to around 60%, plus the fact that this design also has a dichroic between the microlens disk and the pinhole disk helps further isolate rejected light, so reducing background and improving signal-to-noise.  Then, in our case, we can combine with multimode fibre input giving an additional boon for efficiency, uniformity, and signal-to-noise.
 
Sample cross-talk from out of focus planes impacts background in both systems in a similar manner because of their pinhole size and spacing. Overcoming this factor, which gets significant quickly with thicker specimens like embryos, can only be achieved with greater pinhole spacing and an element we chose to focus on as a key design parameter in Dragonfly.

On the emission path, assuming the same power density of light at the sample, then sensitivity and signal-to-noise performance becomes more about management of internally reflected light, dichroic and emission filter performance, and finally the sensitivity of the camera you use.  This is something we have paid particular attention to when we designed Dragonfly.

Then there is the pinhole size itself.  For those who prefer to image with the typical “live-cell” 60/63x (water or glycerol immersion) objectives we use a different pinhole size that optimally matches to their numerical aperture.

Basically, how the different technologies matchup is somewhat dependent on your specific needs.  We all offer something different (illumination optics, with/without microlens, pinhole size and spacing, filter specifications, reflected light management) which you should match to the samples you will work with, and the spatial and temporal resolution you require.  Your decision is best shaped by detailed conversations with specialists from the vendors, peers like the forum, and testing (if that’s feasible in the current restrictions).  Obviously, us companies may well have examples of our technology in publications studying similar or the same cell physiology.

Best
Geraint Wilde, Ph.D.
Product Manager for Life Science Cameras and Microscopy Systems.
Andor Technology