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Adaptive Optics Correcting for Highly Scattering Media: A New Approach

Posted by Angelica Perrone on Thu, May 15, 2014 @ 12:05 PM

Tags: deformable mirror, adaptive optics, Boston University, deep tissue microscopy, Howard Hughes Medical Institute, SLM, spatial light modulator, BMC, imaging systems, two photon, fluorescence

Scattering media can be a real headache if you are looking to achieve high-resolution, deep tissue in vivo images. Without adaptive optics, do not anticipate having the optical control you need to correct for scattering media effectively. But no need to worry, we have a solution.test bed S MPM resized 600

Since standard Multiphoton Microscopy just wasn’t cutting it, the Cui Lab at Howard Hughes Medical Center pioneered a new technique that Boston University also recently developed, called Superpentation Multi-Photon Microscopy (S-MPM). Each group uses a different optimization scheme but the outcome is the same: The enhanced technique permits active compensation of wavefront aberrations in a scanning beam path through the use of a BMC MEMS Spatial Light Modulator (SLM), allowing for increased depth imaging.

Developed at Boston University and commercialized by Boston Micromachines, the enabling components are the Kilo-SLM and the high speed S-driver. With these components incorporated into the test bed shown in Fig. 1, images of 1 µm diameter fluorescent beads through 280 µm thick mouse skull can be achieved at depths of about 500 µm. The SLM corrected low order spherical aberrations as well as higher order scattering effects. Signal enhancement with higher resolution and contrast were improved by 10x-100x. The optimized SLM phase improves imaging over a field of view of 10-20 µm for samples tested to date with techniques currently in the works to improve upon this.

With 600 nm of stroke and 60 kHz of maximum frame rate, the Kilo-S System comes in a variety of options to fit your needs at a much reduced cost over our standard 1000 channel system. Contact us today for more information on our Kilo-S or any of our other systems! 

FAQ: BMC Deformable Mirrors for Laser Applications:Power

Posted by Angelica Perrone on Wed, Apr 02, 2014 @ 12:00 PM

Tags: deformable mirror, adaptive optics, boston micromachines, Boston University, laser beam, laser science, BMC, Mirrors, pulse, pulse width, peak power, laser pulse shaping, ultrafast lasers, laser pulse compression

About half of our customers use our deformable mirrors for laser applications, such as beam shaping or steering. We get a lot of questions pertaining to laser power and handling for both our deformable mirrors and modulators.  Below is a summary of the guidelines we use when discussing our technolgy.

The most important specification to note immediately if you are working with lasers is the damage threshold of our DM's. There are two mechanisms of failure to consider: mirror damage due to heating and coating delamination.  The first failure mode is largely governed by the average power experienced by the DM. The rule of thumb that we follow is maximum average power of 20W/cm². For the second failure mode, the peak energy is of greatest concern.  In this case, the threshold that we use is that of a standard thin-film gold metallic coating, in this case, 0.4J/cm². Depending on the DM system, the calculations may be slightly different. In order to ensure a DM is suitable for your application, we typically need to know as many of the following properties as possible: the pulse width of the laser, peak power, frequency, wavelength and beam size. This last pameter will help to determine which aperture size is required and if you need to change your beam size at all. Additional information on laser power can be found on our previous blog here.

From a power threshold standpoint, our modulator technology works similarly to our deformable mirror technology. However, it may have a slightly lower damage threshold due to the fact that the exposed surface is a thin layer of silicon nitride as opposed to the thicker polysilicon surface used for our deformable mirrors. Honestly, we do not have much experience testing the devices.  If you are interested in carrying out testing, we would be glad to lend you some modulators to test.

If you are interested in learning more about customers' experience with high-power lasers used on our DM's, please click here to read Andrew Norton's paper on laser test performed using our DMs. Also, please visit our website or contact us for questions or additional information on how to obtain a device for testing.

How to select the right deformable mirror for you Part 1: Imaging

Posted by Michael Feinberg on Tue, Jun 15, 2010 @ 02:10 PM

Tags: deformable mirror, adaptive optics, boston micromachines, Boston University, product information, Woofer Tweeter, resolution, response time

deformable mirrorIn this multi-part series, I will be exploring the basic questions that one needs to answer in order to determine which type of deformable mirror is best suited for their application. This list is by no means exhaustive, but if one has an understanding of these topics, the journey to creating spectacular images will be much smoother and equally as rewarding. I am starting with imaging since this is a field that is constantly expanding to new disciplines and often involves researchers who are not familiar with adaptive optics. The next topic will be beam shaping, with further topics to be introduced in the future.
Potential customers come to us at Boston Micromachines to design an adaptive optics system for many different applications: Confocal microscopy, conventional microscopy, astronomy, etc. However, many of them don't know their options when selecting the right mirror. We think we've reduced the questions you need to ask to four simple topics. If each customer reviews this list before giving us a call, finding a mirror best suited for their application will be as exciting as viewing that killer image you're trying to get:

1) Aperture: How big is your image? How big (or small) can you make it?
The size of the wavefront is the first and foremost issue to understand. Some applications have no control over this while others can change the size of their wavefront through the use of some simple focusing optics. Before doing research into your alternatives, you should figure out what your limitations are in relation to this.

2) Resolution: How complex are your aberrations? zernike
Having the right aperture is great, but if your mirror does not have a high enough level of precision, your image improvement will be greatly limited. In the deformable mirror industry, we call this distance between control points, "pitch." In our devices, it is the distance between actuators. In membrane-type mirrors, it will be the distance between electrodes that are underneath but not directly connected to the surface. If your aperture can be manipulated, the precision to which you can control the wavefront will most likely be directly affected by this adjustment. Also, the size of the pitch can affect the price of the mirror. So, understanding what the relationship is between aperture, pitch and price can help you not only find the right mirror, but minimize your costs.

3) Aberration: How big (deep) are your aberrations?DM  Profile
While aperture and resolution cover you in two dimensions, depth is the final critical physical dimension. The size of your aberrations will directly impact the necessary stroke (the distance the surface of the mirror can travel up and down). If you have very small aberrations and require a high level of precision to correct your wavefront, you can focus on MEMS-based solutions, like those provided by Boston Micromachines (available stroke is between 1.5 and 5.5um). However, if you require larger stroke, you may need to focus on more flexible electro-static or piezo-electrically motivated membrane surfaces. Most recently, some have executed what we call a woofer-tweeter approach where a larger mirror corrects for the larger aberrations (the woofer) and a smaller, more precise mirror fine-tunes the image (the tweeter). You can see an article on this in the June 2010 issue of Photonics Spectra: "Dual Deformable Mirror Systems Take the High and Low Roads to Imaging Success." Size of the aberrations is a critical point to understand due the fact that if you don't have enough stroke or high enough level of precision, your image may not improve enough to be impactful.

4) Response: How fast do your aberrations move?
If you're dealing with static medium, then this is not an issue. However, if you are dealing with atmospheric turbulence, as in astronomy, or in vivo conditions in live specimens, then this is a critical parameter. While this is dependent on the structural composition and design of the mirror, it is also dependent on the drive electronics and controller. So, make sure that both your system (PC or other controller) and the electronics associated with the mirror are up to snuff for your application.

Purchasing a deformable mirror should be an exciting endeavor: The images obtained to date have been astounding. I'm sure that with proper preparation and understanding, it can be successful for you as well.

BU to BMC

Posted by Michael Feinberg on Tue, Mar 02, 2010 @ 11:27 AM

Tags: deformable mirror, boston micromachines, Boston University, Photonics Center

A question that is asked from time to time around here is, “What is your relationship with Boston University? “  People want to know:  Are you a spin-off from their incubation program?  Do you receive financial support from BU?  Do they own your technology?  Well, the short answer is yes and no.   Here’s a summary:

We are an independent company which receives no financial support from BU and has a close relationship with the University for a few reasons:

1)      We license some of BU’s MEMS technology manufacturing process from the University so that we may profit from it and contribute back to the University

2)      Our founders are a BU professor (Tom Bifano, Director of the Photonics Center) and a BU grad (Paul Bierden, CEO, BSME ’92, MSME ’94).

3)      We collaborate on focused development which includes both fundamental research and advanced development.

We are connected due to our mutual interest in photonics technology and expertise in the field.  It has been a beneficial relationship to both parties and we hope to continue the relationship as we move forward with new projects and new technological improvements.