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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.

FAQ: BMC Deformable Mirrors: Windows

Posted by Angelica Perrone on Wed, Mar 26, 2014 @ 09:51 AM

Tags: deformable mirror, laser beam, laser science, ultrafast lasers, CW, Coatings


For those interested in using our deformable mirrors with laser applications, there are a few common questions which are asked in regards to the AR-coated window and if it is/can be removable.  Below is a summary of what's standard and what's possible:

Both the optical modulator and our DMs are protected by a 3mm thick window, which are standard BK-7 windows from Thorlabs. The options for windows are: 

  • 350-700nm
  • 400-1100nm
  • 650-1050nm
  • 1050-1620nm
  • 550nm-2400nm

This can also be customized upon request. The windows are mounted on a 6° angle in order to prevent ghosting. 

A lot of requests are in regards to removing the protective window. For our standard DMs, the window is not removable as it is attached with an epoxy. For our modulators, the window IS removable. We highly recommend you DO NOT REMOVE the protective window. The only exception to not having an AR-coated window would be if the DM was operated in a clean room environment.  In this case, we can deliver the modulator or DM without the window and include a protective removable lid instead. In addition, we recommend flowing Nitrogen at a very slow pace around the mirror to ensure the humidity remains low around the DM. The required humidity is <30% as the mirror is made of polysilicon which needs to be protected from corrosion. 

 Please visit our website or contact us for additional questions.

deformable mirrors, BMC,adaptive optics

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.