Acquisition Speed Comparison of MetaMorph, NIS Elements, Micro-Manager

How fast can a typical imaging system really run? What factors affect this? While most research might not require rapid sequential capture, almost all experiments can benefiet from tight exposure/illumination timing, yet few microscope users are aware of timing delays injected into experiments by the control software they are using. So how much delay is caused by software? I’ve long wanted to look into this, and finally got the chance!

In order to accomplish this, I programmed a microcontroller to accept commands from the Lumencor Spectra-X. This high power/high speed LED engine is popular for fluorescent excitation, as a result, almost every available software application can control it. I set up my code to measure the time in which a known shutter, or known wavelength command was received on the serial line (well, USB serial).

The team at Technical instruments were kind enough to loan me the use of their equipment, so a generous thanks to Reese Allen and the entire Technical instrument staff!

Experimental conditions were as follows:

• All software packages were installed on a clean OS install of Win7/x64
• Test machine was a Dell Precision series
• Tests were performed by configuring the camera to run ~100fps. This was accomplished using a 4×4 binning, and an exposure of 9.8mS.
• All software applications were set to send at minimum one shutter and one wavelength change per acquisition cycle. (i.e. 1 picture from the camera, + 1 wavelength change + open shutter, then switch wavelength and cycle shutter).
• All applications were first tested in a “free run” mode, to confirm the camera configuration was capable of 100fps at minimum.
• No other devices were installed for these tests.

The results were quite interesting:

Here are some videos showing each of the programs performing. You can see some timing variation (likely caused by my capture device) but the averages are easy to resolve, and they correlate to the speed seen on the captured image stacks.

NIS Elements

Micro-Manager

MetaMorph

What becomes quickly apparent is the influence of asynchronous device control using metamorph’s “Stream” function. This is making use of a patented computer-based device sequencing technique. This technique waits for a camera “event flag” (interrupt) to fire, and when it does, a pre-defined set of events occur which control devices. This is similar to what many external trigger devices do, such as a configured national instruments card , or a pulse oscillator, or the triggerscope. The key difference here is that an external card and/or device isn’t needed, this occurs within the PC itself.

Some further thoughts:

• Micromanager is a great open-source competitor to other pay-for solutions. Good speed performance for a low up-front cost! (the cost of setting it up!)
• It’s interesting that this never really seems to come up for 90% of customers who purchase “high speed” devices. Either the exposure times needed for acquisition of dim signal are so long as to never reach the speed thresholds shown here, or the capture frequency needed for a given study doesn’t require these speeds, or some other cause, but in my experience this is rarely a complaint on behalf of clients. Why isn’t this a bigger problem?
• Many, many devices can’t reach the speeds shown here. In my tests I was using an LED driver. LED’s should have a switch time in the <5mS range. The slowest components usually found on a common automated microscope are the filter wheels and turrets, which usually run at the 50ms range when fully loaded with filters. (that’s on the fast side). So is this the reason the problem isn’t exposed more often?
• By far, the slowest components you’ll find for microscopy are found on automated microscopes. Shutter open/close times on a common scope (i.e. big 4 name brand scope) can be in the upwards of 100ms! Moving a big filter turret usually takes 200mS. Again, this begs the question of how important speed really is for the common researcher….
• For those who want the fastest possible speeds, have no fear! I’ll be announcing some major improvements to my triggerscope soon, to include programmable high speed sequencing capability!

-Austin