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FAQ: Flatness of BMC Deformable Mirrors

Posted by Angelica Perrone on Thu, Jan 16, 2014 @ 11:36 AM

Tags: deformable mirror, adaptive optics, boston micromachines, mirror technology, spatial light modulator, BMC, imaging systems, Mirrors

Happy New Year! Hope everyone had a great holiday and is staying warm.

To continue addressing our FAQ's, another recurring question BMC recieves is on the flatness of our deformable mirrors.  The figure below shows an unpowered BMC DM and a flattened BMC DM. 

Flatness

The surface figure of our unpowered deformable mirrors has a low-order surface bow. The amount of stroke needed to flatten the DM is between .5 µm and 1 µm, depending on the model. We can guarantee that the stroke needed to flatten the deformable mirror will not exceed this amount and tends to be lower for the lower stroke devices.

However, researchers in the past have been able to achieve flattening the wavefront without using up any stroke on the DM. If you are able to include additional optics into your setup, the low order bow can be taken out with static optics. Just something to keep in mind as you are designing your system and trying to determine how much stroke is required to achieve your wavefront correction needs.

If you have any additional questions in regards to the flatness of our mirrors or are interested in seeing what the typical unpowered surface figure is, please contact us at moreinfo@bostonmicromachines.com or visit us online at www.bostonmicromachines.com

FAQ: BMC Deformable Mirror Reflectivity

Posted by Angelica Perrone on Fri, Dec 20, 2013 @ 09:00 AM

Tags: deformable mirror, adaptive optics, boston micromachines, product information, mirror technology, BMC, Mirrors, Coatings, Reflectivity, Thorlabs

Over the past couple of months we have been receiving an assortment of questions in regards to our products. We thought it would be a good idea to share the more popular questions and answers as they stream in to keep everyone updated.

One question that tends to be asked quite often is the reflectivity our deformable mirrors can achieve. This depends on a couple of factors such as mirror coating, protective window AR coating and the wavelength of the light. 

Figure 1

We offer gold, aluminum and protected silver coating on almost all of our deformable mirrors. When selecting a coating, you should pay particular attention to the wavelength(s) of light you use. The BMC DM Coating Reflectivity chart to the right illustrates the reflectivity of each of our standard coatings.

Our standard windows with AR coating are BK-7.  We offer a few options, depending on which size mirror you select.  For our smaller DMs, we offer the standard coatings from Thorlabs as well as a few more versatile options.  You may choose either uncoated, 350-700nm, 650-1050nm or 1050-1620nm.  We also offer a 400-1100nm window and 550-2400nm, the latter for an additional cost.  For our larger DMs, various coating options are available. We do offer customizable options for an extra fee, so please contact us with your specifications if you require this.

The N-BK7 Broadband Antireflection Coatings chart from Thorlabs below depicts the percentage of  light lost for each AR coated window. Similar curves are available for our other coatings.Antireflection coatings Thorlabs
               

If you are looking for additional information on our standard windows, please visit our friends at Thorlabs online. If you have any further questions on the reflectivity of our mirrors, click here to send us an e-mail or visit us online at www.bostonmicromachines.com

Improved Retinal Imaging Resolution with the AOSLO

Posted by Angelica Perrone on Fri, Dec 06, 2013 @ 03:30 PM

Tags: adaptive optics, boston micromachines, biological imaging, imaging systems, retinal imaging, microscopy, Adaptive Optics Scanning Laser Ohphthalmoscope, Joslin Diabetes Center, OCT, ARVO

It has been quite some time since our last blog post due to a great deal going on at BMC! Alongside some new product releases, we recently made a few adjustments and updates to our ophthalmic imaging instrument, the Adaptive Optics Scanning Laser Ophthalmoscope (AOSLO) which we are releasing early next year.

This next-generation instrument allows in vivo retinal imaging on a cellular level and is currently undergoing beta testing at the Beetham Eye Institute at Joslin Diabetes Center, led by Dr. Jennifer Sun and her team. There it is being used to directly quantify features such as cone density, microaneurysm size and measure blood flow through the microvasculature in the retina. By pairing a Scanning Laser Ophthalmoscope (SLO) with advanced Adaptive Optics, it offers the advantage of imaging the retina at a resolution 2-3 times that of a standard SLO. 

The AOSLO is also capable of measuring various properties of retinal cone physiology. Due to its enhanced imaging and software, it enables evaluation of the following attributes:

  • Cone Density
  • Nearest Neighbor Distance
  • Voronoi Tessellation Tile Area
  • Effective Radius
  • Packing Factor

The AOSLO’s ability to measure such features allows early stage detection of visual decline due to diabetes. This can be identified by the decrease in cone regularity, cone mosaic changes, cone reflectance and a decrease regularity of cone spacing. This function of the AOSLO can help determine early treatment plans for patients and generate further investigative studies.

                When testing out the AOSLO at Joslin, we found something very interesting out about our CEO, Paul Bierden. The pictures below depict his own retina, discovering that he has a microaneurysm! This was unexpected news, since normally it would be undetectable by any other retinal imaging systems. 30% of the microaneurysms imaged using the AOSLO at Joslin were not visible in fundus photos. The AOSLO is able to accomplish this by evaluating the vascular and neural retinal planes in vivo with cell-scale resolution. The pictures below also point out the microaneurysm attributes that can be measured. They are:

  • DimensionMicroaneurysm measurmens
  • Presence of lumen clot
  • Wall reflectivity

 

Lastly, the AOSLO is able to measure small-vessel blood flow. This is done with the help of its enhanced imaging qualities, instrument optimization and post-processing software. By stopping a horizontal scan over a blood vessel, it can measure the blood velocity by tracking the moving erythrocytes over a scanning line. With this information, researchers can produce a blood velocity profile for retinal vessels. See the video below to see how it’s done!

If you have any interest in using the AOSLO, let us know!  Please give us a call and let us know about your research. We are accepting orders for the new instrument and are open to collaborative grant applications to secure funding. If you are interested in seeing the AOSLO in action, we are setting up appointments now for the next few months.  We hope to hear from you soon!

Further focus at CLEO 2013

Posted by Michael Feinberg on Tue, Jul 09, 2013 @ 12:54 PM

Tags: deformable mirror, adaptive optics, boston micromachines, laser beam, laser science, biological imaging, deep tissue microscopy, BMC, two photon, free-space communication, modulating retroreflector, optical chopper, optical modulator, chopper, UAV, pulse, pulse width, laser pulse shaping, ultrafast lasers, CLEO, AOM, acousto-optic modulator, speed, shutter

It's been a few weeks since we returned frocleo resized 600m the Conference on Lasers and Electro-Optics 2013 and now that we're settled back in to the daily routine, I thought I would give some highlights on the show. I was happy to be joined this time by our new Marketing and Communications Specialist, Angelica Perrone, who did a great job navigating the complex photonics market for the first time.

While the conference seems to be chugging along at a nice pace, the tradeshow has most definitely become a smaller venue.  We were once again hosted by our strategic partner, Thorlabs (thanks, again guys!) and being in such a central location on the floor, we were able to get a good flavor for the pace of the show.  Here are my thoughts:

Little, different, yellow, better

Anybody get that Nuprin reference?  Anybody? See what I 'm talking about here.

Okay, so it's not yellow (although yellow lasers are cool), but the show is definitely getting smaller.  I mentioned to a colleague that since the show is in San Jose for the second year in the row, it seemed like the barriers on either end of the tradeshow floor had moved in just a bit. 

As far as different, the show is not like other photonics shows in that it is pretty focused in its applications.  While there were some interesting talks on microscopy, this was a small portion of the material, with most others focussing on more laser-centric applications, as the title of the conference implies. 

As far as better, I would say that for BMC, it was most definitely better for our new products:  The Reflective Optical Chopper(ROC) and the Linear Array DM.  We recieved more interest in these products over our legacy deformable mirror technologies. This is exciting for me as a product marketer and salesperson and even moreso as a member of a company that is always looking for new avenues for our technology. We see the ROC being useful for users who span from pure laser scientists to imaging engineers interested in chopping a beam at high speed with either a constant or variable duty cycle.  The linear array has already proven useful in pulse shaping applications as described in our whitepaper, which is available for download here.  Both products are available for purchase now.

Our Wavefront Sensorless Adaptive Optics Demonstrator for Beam Shaping (WSAOD-B)also generated some buzz. More and more applications which require wavefront correction are surfacing and need a solution without a wavefront sensor.

In all, it was a good show that has given me and my team work to do as we explore more exotic applications for our technology.  I look forward to joining the show again next year and I hope to connect with all of you again in the near future!

For more information on the products mentioned above, please visit our website and download our whitepapers.

Reflective Optical Chopper Outperforms the Rest

Posted by Angelica Perrone on Thu, Jun 20, 2013 @ 02:11 PM

Tags: adaptive optics, boston micromachines, product information, response time, BMC, free-space communication, modulating retroreflector, optical chopper, optical modulator, chopper, pulse, ultrafast lasers, CLEO, AOM, acousto-optic modulator, SNR, signal-to-noise, speed, shutter

As Boston Micromachines' newest member, I would first and foremost like to introduce myself. My name is Angelica and I have joined the BMC team as their Marketing and Communications Associate. It has been some time now since our last blog and I thought it would be appropriate to discuss our most recent product; The Reflective Optical Chopper, or ROC.ROC with driver 130326 No Logo

               Optical Choppers, being frequently used for signal recovery in improving signal-to-noise ratio, are used to convert a continuous laser beam into a chopped one. Traditional Optical Choppers offer various pains, such as the need to alter the beam size to fit through wheel spokes, challenging stability at low speeds, the need for costly lock-in amplifier equipment and complex calibration procedures. The innovative, low-cost ROC simply eliminates all of these, outperforming traditional optical choppers.

                Drive electronics are paired with BMC’s MEMS Optical Modulator technology to create the ROC. The ROC provides beam chopping at impressive speeds without beam size modification. With a frequency range of DC to 150 kHz with better than 40 µs response time, control increments of .01 Hz and a contrast ratio exceeding 90% up to 100 kHz, the value of the ROC ‘speaks’ for itself. For signal-to-noise ratio improvement, the drive signal can be used as the sync signal, allowing it to be painlessly synchronized.

                Many industrial, scientific, medical, aerospace and military applications call for the need of reliable and advanced equipment. The ROC has superior capabilities such as high speed, large frequency range, reliability, stability and usefulness in SNR improvement applications. Basically, the Reflective Optical Chopper is an advance in optical chopping technology which is available at a low price.

Fast and Precise Laser Pulse Compression with the Linear Array DM

Posted by Michael Feinberg on Wed, Nov 07, 2012 @ 10:33 AM

Tags: deformable mirror, adaptive optics, boston micromachines, laser science, Janelia Farm Research Campus, microscopy, laser pulse shaping, ultrafast lasers

Linear ArrayUltrafast lasers have been extensively used in ground breaking  research including two Nobel Prizes.  Applications within spectroscopy, photochemistry, laser processing and microscopy are widespread.  However, to capitalize on such short laser pulses, a pulse compressor is required to compensate for the dispersion induced by optical elements. Liquid crystal based spatial light modulators are most commonly used in laser pulse compressors.  Although a proven technology in display applications, liquid crystals have drawbacks including phase jitter and a limited fill factor.  Researchers at the Cui Lab at HHMI’s Janelia Farm Research Campus looked to Boston Micromachines Corporation’s prototype Linear Array Deformable Mirror (DM) to address these challenges.

To evaluate the performance of the pulse compressor, the laser pulses were analyzed with frequency resolved optical gating (FROG) using a commercial instrument (Grenouille, Swamp Optics, Atlanta, GA). In Figure a and b, the temporal and spectral profile of the pulse is shown when a flat wavefront is displayed on the DM. Evidently, the pulse is distorted and the spectral phase is not flat at all (a flat spectral phase is required for a transform limited pulse). Next, the beam returning from the pulse compressor was focused with a concave mirror onto a GaAsP photodiode and the resulting nonlinear signal was used as a feedback for the correction algorithm. After optimization using a technique called Phase resolved interferometric spectral modulation (PRISM), the temporal profile (Figure c) shows a dramatically shorter, Gaussian shaped pulse. The spectral phase is perfectly flat (Figure d) with less than 0.01 radians phase error and is stable in time. These results suggest that the precision and stability of the Linear Array DM allows close to perfect restoration of transform limited laser pulses.  For more information on the optimization technique, you can access a scientific publication here.

 

 pulse compression, FROG, pulse shaper

 

In our next blog post, we will discuss the results of the use of the Linear Array DM in an interesting two-photon microscopy experiment.

More details can be found in our Linear Array white paper which includes a more detailed description of this application.

What Do You REALLY Want in a Deformable Mirror?

Posted by Michael Feinberg on Wed, Oct 17, 2012 @ 04:00 PM

Tags: deformable mirror, adaptive optics, response time, laser science, mirror technology, microscopy, astronomy

This past summer, Boston Micromachines Corporation conducted a survey of nearly 300 members of the business and scientific community to find out what features were valued in a deformable mirror for adaptive optics and other wavefront correction applications.  Respondents came from our three major vertical markets: microscopy, deformable mirror survey resized 600astronomy and laser science.  In this survey, we asked some fundamental questions and had respondents choose between three DMs with properties varying in categories of actuator count, stroke, response time and price in various combinations. We were able to drill down to what each respondent valued.  Here are some of our key findings:

1)      Actuator count was the most valued property

Across all verticals, this was true.  Overall, respondents preferred an  average of 1000 actuators. While microscopists preferred 140 actuators by almost 2 to 1 over other models, those who identified as laser scientists were looking for an average of 1001 actuators and astronomers preferred, on average, 1800 actuators.

This was very interesting to us considering we are the only player in the market to provide deformable mirrors with these actuator counts as standard products or are developing DM systems which meet these specific needs (we have a 2000 element mirror in the works).

2)      High speed is important

The most frequently chosen option for response time amongst laser scientists was 50μs and all other disciplines preferred average response better than 300μs. This is great news for the industry considering that most mirror architectures can respond adequately to meet the needs of the users. Our DM architectures are available with response times up to 22μs and we are able to drive these mirrors with our X-Driver (response time down to 4μs), satisfying high speed requirements as well.

3)      Low price is desired

As we hear so often, most users were looking for low-priced devices. This was the second    preferred property after actuator count. While those of us in the industry talk about lower prices with higher volumes, the volumes just haven’t been there yet to make this prophecy come true.  The hope in the future is that the DMs based on scalable technologies, such as MEMS, will take off and lower-priced devices will be available.

We definitely learned a lot from this survey, above and beyond what is mentioned above.  If you have any questions about our methods or are interested in discussing more specifics about the responses, I would be glad to chat further.  Just contact me at support@bostonmicromachines.com.

 

Wavefront Sensorless Adaptive Optics Now a Reality

Posted by Michael Feinberg on Mon, Oct 01, 2012 @ 11:57 AM

Tags: deformable mirror, adaptive optics, boston micromachines, laser beam, laser science, mirror technology

WASO for blog

 

Up until recently nearly all adaptive optics (AO) systems used wavefront sensors for correction. But with recent advances, off-the-shelf wavefront sensorless AO is becoming a reality.  Benefits of this type of AO include enhanced aberration correction due to the elimination of non-common path errors and wavefront sensor noise.

BMC has developed a Wavefront Sensorless AO Demonstrator (WS-AOD) which provides a platform for utilizing metric-based wavefront control with BMC MEMS deformable mirror (DM) technology. While conventional AO systems perform closed-loop DM control using direct measurements of the wavefront as feedback, the metric-based approach uses details in the aberrated light to improve clarity. Two versions are available; one is optimized for beam shaping applications and the other is designed for imaging applications.

We see laser beam shaping as a key area in this exciting technology and our demonstrator is built to address the unique challenges of this field. Our WS-AOD serves as an introduction to wavefront sensorless adaptive optics principles. It allows users to understand the details involved in properly implementing a metric-based adaptive optics solution on an optical system. The demonstrator can also be used as a stand-alone aberration compensator. By introducing aberrations in the sample stage, the system can be optimized for a multitude of use cases from laser research applications to scanning laser microscopy. Additionally, the user can easily integrate the hardware into an existing optical system and utilize the open source software code for metric-based correction.

describe the image 

 

Schematic of WS-AOD for beam shaping applications. Also available for imaging applications.

To compensate for phase aberrations the WS-AOD uses BMC’s deformable mirror (DM) technology. BMC’s DM is a continuous facesheet deformable mirror that is controlled by hysteresis-free electrostatic actuators located on a square grid. The full DM activemulti DM aperture can be as little as 1.5 mm to as much as 25 mm across. Each actuator can provide up to 5.5 µm of mechanical stroke, which corresponds to about 11 µm of phase control. The electrostatic actuator array is driven using independent high voltage channels with 14-bit resolution. This corresponds to sub-nanometer displacement precision. The drive electronics can provide frame rates of from about 4.6 kHz up to 100 kHz.

The control software for WS-AOD allows the user to correct for aberrations introduced as well as generate a random aberration using the DM. The software is open source code based in Mathwork’s Matlab and runs on platforms using Windows operating systems. By utilizing the included algorithm to manipulate the mirror surface, the mirror compensates for aberrations and converges to an optimal profile. The user has access to the open source code to balance correction capability between maximum signal and minimal time.

To learn more please click here for a copy of our Wavefront Sensorless Adaptive Optics white paper.

Dr. Meng Cui of HHMI Discusses Deep Tissue Microscopy Technique

Posted by Michael Feinberg on Wed, Aug 01, 2012 @ 02:39 PM

Tags: deformable mirror, adaptive optics, biological imaging, deep tissue microscopy, Howard Hughes Medical Institute, Janelia Farm Research Campus

hhmi logo

Our customers are constantly making exciting scientific discoveries and we’re proud of the part our deformable mirrors play in their research. Dr. Meng Cui, Lab Head at Howard Hughes Medical Institute, Janelia Farm Research Campus recently presented the Iterative MultiphotonAdvanced in Biological Photnics Adaptive Compensation Technique (IMPACT) that his team has developed for deep tissue microscopy at a webinar on “Advances in Biomedical Photonics”.  In Dr. Cui’s presentation he discussed IMPACT which utilizes iterative feedback and the nonlinearity of two-photon signals to measure and compensate wavefront distortion introduced in tissue.  He gave details on the imaging results on a variety of biological tissue including brain tissue through mouse skull and labeled  T cells inside lymph nodes and compared his team's technique with conventional adaptive optics methods.   For more details on Dr. Cui’s research you can view the entire webinar which was presented by Photonics Media at http://www.photonics.com/Webinar.aspx?WebinarID=21.  Details of the research can be downloaded from the following site: http://www.pnas.org/content/early/2012/05/09/1119590109.full.pdf

CLEO 2012: Concentrated Interest in Adaptive Optics

Posted by Michael Feinberg on Wed, Jun 06, 2012 @ 03:49 PM

Tags: deformable mirror, adaptive optics, boston micromachines, laser science, biological imaging, astronomy, CLEO

BMC at CLEO

This year, the CLEO Conference had its normal interesting character:  A variety of users from hardcore laser scientists to focused business interests to laser scanning imaging folks.  BostonMEMS Optical Modulator Micromachines took our position within the Thorlabs booth for the 5th year(thanks again, guys!) and demonstrated some great technologies that we think will make an impact in the industry.  Our MEMS Optical Modulator  generated a fair amount of interest and prompted some great questions about its capabilities and possibilities.  We showed its flexibility by demonstrating how with a simple input signal and an amplifier, a reflective diffractive element can be used to couple light into a fiber at varying frequency and amplitude.  We went into the show thinking this would be the big topic of conversation.  While we did have some great conversations and we’re more than happy with the response, the real star of the show was our Wavefront Sensorless Adaptive Optics Demonstrator for Beam Shaping. Users from all walks of the laser industry approached me with potential uses from wavefront characterizationWavefront Sensorless Adaptive Optics Demonstrator techniques to photon counting.  I learned that the simplistic nature of the kit (maximize a signal through a pinhole) allows researchers with very different backgrounds to think of interesting ways to take advantage of its versatility.  We found that the simple, clear spot on the screen was enough to entice microscopists and laser scientists alike to brainstorm interesting ways in which to integrate the deformable mirror, detector and algorithm of the system into their latest work.  I am looking forward to some great follow-up conversations!

I did get the chance to venture out of the booth for a few talks as well as touch base with some new and old friends.  Major impressions:

1)      AO is still not a major player in laser science

While there were some interesting topics and uses of deformable mirrors and spatial light modulators, the technique is by no means pervasive as in other industries such as astronomy or biological imaging.  Other techniques such as MIIPS (congratulations again, Dr. Dantus) serve the industry and are well proven to be able to satisfactorily shape pulses. Another theory:  Laser scientists prefer to go after the laser for improvements instead of supplementary hardware.  This could be for a variety of reasons such as: a) extra hardware means lost light, b) this is where they are comfortable and love to tweak things or c) the cost is just too high right now.

2)      Beam characterization is becoming more affordable

With a few companies introducing higher speed and lower cost wavefront sensors, the market is becoming more accessible to more researchers.  This can only be good for everyone.

3)      Booth traffic is down, but more focused

In past years, my conversations were usually an even split between educating the visitor about the basics and having in-depth discussions about the capabilities and possibility of integrating devices into optical systems.  This year, the split was more like 75/25 in favor of detailed discussions.  Many are well aware of the background and of the 75%, at least half approach me with well thought-out ideas.  It is very refreshing and encouraging to have these discussions and I suspect the ratio will continue to grow as years go by.

Overall, it was a productive show.  I look forward to returning to San Jose next year and introduce exciting products that we have in our product roadmap and get more people to shape their light!