Using AOTF Hyperspectral Imagers in the
Fight Against Cancer

Dr. Trivedi (left) and Brimrose Research Engineer, Sterling Walsh evaluate a culture sample using an acousto-optic tunable filter hyperspectral imager.

Dr. Trivedi (left) and Brimrose Research Engineer Sterling Walsh evaluate a culture sample using an acousto-optic tunable filter hyperspectral imager.

Throughout the past 20 years or so, Brimrose has had a rich and storied history of providing its acousto-optic tunable filter (AOTF) technology to meet a variety of different needs, which can range from archeology to crime scene detection. Undoubtedly one of the most exciting applications is the detection of cancer, where our AOTF technology has been used in several ways.

In fact, the use of our AOTF technology in this area has given us a seat at the table of a fascinating new technology known as biomedical photonics, or BioPhotonics for short. This is changing the face of medicine, allowing us to view and operate in the human body as never before. More specifically, the use of our instruments is part of a new and growing field known as medical hyperspectral imaging, or MHSI. The use of MHSI does not require the introduction of agents, which is advantageous compared to imaging techniques that require contrast agents.

While I don’t want to get too technical, MHSI is a novel, camera-based method of imaging spectroscopy that integrates spatial and spectroscopic data from tissue in a set of images. MHSI delivers near-real-time images of biomarkers in tissue. It is a promising method for the noninvasive, rapid and inexpensive evaluation of cancer in the tumor bed.

A hyperspectral imaging system is mainly composed of the light source, wavelength dispersion devices and area detectors. The rationale for cancer detection by optical imaging lies in the fact that biochemical and morphological changes associated with lesions alter the absorption, scattering and fluorescence properties; therefore, optical characteristics of tissue can in turn provide valuable diagnostic information.

AOTF Technology: Improving Cancer Detection One Wavelength at a Time

Brimrose’s AOTF technology is a core technology for the company.  AOTF technology allows us to scan hundreds of wavelengths per second, while also capturing critical data at any one or more of these precise wavelengths.

One of the first medical applications where our AOTF technology was used was for the Advanced Biomedical Science and Technology Group at Oak Ridge National Laboratory in Tennessee. The technology was adapted for the purpose of identifying skin cancer. This involved using the AOTF hyperspectral imager to detect cancerous tumors in mice.

The Oak Ridge researchers involved with the study were well pleased with the results: “Hyperspectral imaging sensors provide contiguous spectral signatures obtained from dozens or hundreds of narrow spectral channels. This enables hyperspectral imaging to reveal more useful information for material identification than conventional imaging techniques,” they found. (1)

Their conclusion: “The proposed hyperspectral fluorescence imaging technique can lead to the development of non-invasive in vivo detection of skin cancer without the need of tissue biopsy.” (2)

Another MHSI system with AOTF Brimrose provided to Chinese researchers was used in the evaluation of cancerous tongue tumors.

The results were rather extraordinary: A recognition rate of 96.5 percent was achieved by the researchers. They concluded: “The experimental results demonstrate that the system has great potential as an important imaging technology for medical imaging devices that provide additional diagnostic information regarding tissues under investigation. Although the final diagnostic decision remains the burden of physicians, the system supports physicians during decision making.” (3)

The system designed also included fiber probes for image signal collection, an endoscope, a laser excitation source, an endoscopic illuminator, an intensified charge-coupled device color camera for reflectance detection, a similar camera for fluorescence imaging, and a spectrometer for single-point spectroscopic measurements.

The Brimrose AOTF product also was used with a hyperspectral imager for the detection of cancer in skin, the breast, lungs and the tongue in collaboration with Columbia University Hospital.

Hyperspectral imaging sensors provide contiguous spectral signatures obtained from dozens or hundreds of narrow spectral channels. This enables hyperspectral imaging to reveal more useful information for material identification than conventional imaging techniques.

AOTF: Increasing our Understanding of Numerous Cancers

For example, the ability of AOTF technology used with hyperspectral imaging to provide a wavelength by wavelength analysis of tissue also sets it apart from multispectral imaging, which does not provide that degree of detail. This is critical as different types of cancer are found in focused, limited spectral ranges. For example, ovarian cancer is detected in the 400-640 nm spectral range, prostate cancer in the 450-950 nm range, melanoma in the 364-800 nm spectral range, etc. (4)

Medicine is slowly but methodically discovering the secrets of disease in the human body. An important way to do that is through ways to better understand what is going on in the human body through imaging processes.  Hyperspectral imaging represents an important tool as we further make progress in discovering those secrets.

The future looks bright for MHSI. We expect that MHSI will play an important role for noninvasive disease diagnosis and monitoring, identification and quantitative analysis of cancer biomarkers, image guided minimum invasive surgery, targeted drug delivery and tracking and pharmaceutical drug dosage assessment.

Brimrose now offers the complete AOTF hyperspectral imaging unit, in both the SWIR and NIR ranges.

 Dr. Sudhir Trivedi is director of R&D at Brimrose Corporation, a position he has held for more than 20 years.

For more information about this blog, please call Brimrose at 410-472-7070 or send email to


  1. “Hyperspectral Fluorescence Imaging for Mouse Skin Tumor Detection,” by Seong Kong, Matthew Martin and Tuan Vo-Dink, ETRI Journal, Volume 28, Number 6, p. 775.
  2. Ibid
  3. “Tongue Tumor Detection in Medical Hyperspectral Images,” by Zhi Liu, Hongjun Wang and Qingli Li, Sensors 2012, 12, 162-174.
  4. “Medical Hyperspectral Imaging: A Review,” by Guolan Lu and Baowei Fei, Journal of Biomedical Optics, January 2014, 010901-4.
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Moisture Analysis in Food Becomes
an Opportunity for Our Spectrometers

Evan Ramer performing spectral analysis

A beautiful thing about working with spectrometers is that you don’t always know where the next application is going to come from. These are great instruments that allow us to see and understand materials well beyond what we otherwise would be capable of knowing.

Several years ago, we were contacted by someone from a company involved with programmable logic control, or PLC. They explained that a large food-producing company that they were doing business with was having problems maximizing its moisture content in the manufacture of bread bi-products. Food companies these days often have large quality-control units where they do sophisticated food analysis using process analytical technology or PAT.

Why is moisture content important?

Well, moisture is water and water doesn’t cost much compared to other ingredients in bread and bread crumbs. People also don’t like bread that is too dry and brittle. This may seem like a small matter until you multiply croutons or crackers by a million or billion. Then it becomes very important.

The challenge for the food production company was to get close to the maximum amount of moisture allowed by law, without going over it. If you exceed the acceptable moisture content, there are problems with mold.

The spectrometer we used, the Brimrose Luminar 4030, was able to consistently provide moisture content of between 10 percent and 12 percent, which is exactly what the company hoped for.

The result was that they saved $170,000 in the first four months of use. Needless to say, the company was very happy. The result was that they bought our spectrometer (we had originally loaned it to them), and have since bought four more. We are anticipating additional orders.

The Luminar 4030 is perfect for these applications. It is small, compact and rugged and integrates easily into the production environment. It is vortex-cooled with a heat exchanger that easily replaces hot air with cooler air. The 4030 can and normally operates 24 hours a day, seven days a week, 365 days a year.

How does it all work?

The crumbs or other bread bi-product goes through an oven to be baked before they go to the hoppers to be packaged. The trick is to set the oven at the right temperature so the right amount of moisture will be baked out of the crumbs.

Cables connect the Luminar 4030 spectrometer to the PLC unit, which in turn interfaces with the oven. The spectrometer tells the PLC what percentage moisture is coming out in the bread and the PLC unit in turn adjusts the temperature of the oven to the optimum setting. In essence, our spectrometer controls the oven.

Robert Newton of Kerry Corporation is very excited about the capabilities of the process. “We’ve interfaced our first unit via PID loop to thermal bake technologies in an effort to optimize the moisture content of our products,” he says. “Our application is a real-time iterative approach that not only optimizes the desired output, but has eliminated product rejections due to over and under drying. Our pilot application has returned well over six figures in the first eight months of continuous operation. We expect similar returns with the installation and commissioning of four additional units in like processes across the Americas Regions.”

With endorsements like these, I have to believe this market will continue to grow together with the food processing industry.

If you would like to talk more about this application, you can call me at 410-472-7070.

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How Our Frequency Shifters Become Known
for The OCT Market

Hello there! Welcome to my first Brimrose Blog. My name is Mark, and I’ve been a test engineer here for about 20 years. If I am being a bit informal, I am new to “blogging,” so please excuse me. If you are new to Brimrose, or “acousto optics,” I’ll try to enlighten you a bit as to what we do, and why people pay for it. So, as my mother asks me, “what do you do?” Basically, we help our customer manipulate light. Well, that’s fine you say, but what good is it? That turns out to be a rather interesting question, especially if you have a heart…

About ten years ago, a U.S. research hospital ordered some frequency shifters. A frequency shifter slightly changes the frequency of the light going through it; another way of looking at frequency shifting is frequency shifters change the color of the light passing through them toward more blue (upshift) or more red (downshift.) A short while later, the same research hospital ordered some more units; well, good, I thought, a repeat customer. Then a Japanese company, at the time obscure to us, ordered similar frequency shifters, but fiber pigtailed units rather than free space shifters. The US research institute would order some, then the Japanese company would order some, and the pattern would repeat; the amount of frequency shift would sometimes vary, but otherwise the specifications were always pretty similar. A few years ago, the US research hospital’s orders dwindled… but the Japanese company’s orders jumped, big time, to orders of over a hundred at a time. It was clear that something big and serendipitous was happening, and we are excited to be part of it. Turns out, the Japanese company, a supplier to worldwide medical markets, and the US research hospital were developing the same thing, Optical Coherence Tomography (OCT), for looking at the tissue and plaque around blood vessels.

Simply put, OCT is a technique for obtaining sub-surface images. It does not use radiation, which is a major plus. It is effectively a type of “optical ultrasound,” providing imaging reflections from within tissue to provide cross-sectional images. Its resolution can be 10 microns, better than other imaging processes such as MRI. It is filling an important gap between cellular imaging and tissue and organ imaging.

I suppose you are saying, “But weren’t you talking about frequency shifters, how do they fit into Optical Coherence Tomography?”’ Well, frequency shifters are a major component of interferometers, devices where a beam of light is split, made to go to different paths, and then recombined. The light is affected by its journey, and the recombined beams “interfere” with each other, giving a picture of where they have been, be it through the air of a laboratory, or the plaque of someone’s arteries.

Neither I, nor anyone at Brimrose, initially realized what problem those first frequency shifters were being applied to, nor that that they would eventually lead to large orders from the Japanese customer. Supplying large quantities of devices for medical uses has had its challenges. Demand for a high degree of consistency, low outgassing, RoHS compliance, materials and processes tracking and documentation have been some of the useful headaches the journey has given us.

Brimrose has other interesting technologies, which is why I stay around, that could have similar potential medically or otherwise beneficial applications. A Brimrose core technology is acousto-optic tunable filters which operate from the UV well into the near-IR range. Optical switching. Optical ‘tweezers.’ More on those later, maybe, if there is interest.

I think our willingness to work with customers to the specifications they desire is a key characteristic of Brimrose’s and has helped us in this journey. If you would like to know more about our frequency shifters, you can call at 410/472-7070.

Keywords: frequency shifter, optical coherence tomography, OCT, RoHS compliance, Optical switching, Optical tweezers.

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Think Globally: Brimrose AOTF-NIR Spectrometers Demonstrate Olive Oil Production in Israel

Making excellent spectrometers has been part of the Brimrose heritage dating back to the company’s founding. It is exciting to be part of a product that has been in the middle of so many large industries for so long—and continues to get better.

Beginning in 1997, Brimrose pioneered a special design of its real-time, dual beam, high-speed capability for blend uniformity in cooperation with a major pharmaceutical company.

At about the same time, we demonstrated high speed (> 80 vials per minute) analysis of an anesthetic suspension with Astra Zeneca. As early as 1999, we demonstrated the high speed (>300 vials per minute) moisture determination in moving lyophilized vials, achieving SEP<0.1%. This pioneering work was done in collaboration with Dr. Lars Sukowski from Roche Basel, Switzerland, who published this work in his doctoral dissertation.

We have expanded into numerous applications in the pharmaceutical, chemical, agricultural, food, polymer and other industries over the years.

Over the past two years, using the Brimrose Luminar 4030 Analyzer, we worked with olive growers and mills in Israel, in cooperation with a world expert on olive mill optimization to increase the yield of the oil without sacrificing quality. (see video) To put the losses due to non-optimal performance in simple terms we can say that for each 10,000 pounds of raw olives processed, about 400 pounds to 1200 pounds of oil are lost in the solid waste. A mill that processes about 10,000,000 pounds per year can increase its revenue by about $140,000 by reducing the lost oil by about 15%.

Brimrose Luminar 4030 Doing Olive Oil AnalysisClose

In today’s world, where revenues from olive oil have dramatically declined due to increased supply from new plantations in Chile, Argentina, Australia, and California, efficiency of mill operation is the key to survival.

The implementation of the Brimrose at-line technology–combined with our speed of analysis and the excellent trending display on the computer screen–has enabled the mills to cut the level of oil in the waste by about half, while maintaining maximum capacity and retaining all of the important qualities of the oil.

Related to this work, a pioneering effort has been going on in Spain, driven by Technilab, our representative there, where a major mill implemented the Brimrose multiplexer technology to monitor several points in the extraction process. This spanned from the crusher, through the malaxer, through the decanter and to the final solid waste. Spectral data from all of these process points is collected in real time and analyzed, providing the mill with real- time feedback as to the efficiency of the process. The result has been that the mill has been able to achieve maximum yields without sacrificing quality.

Realizing that the overall economic viability of olive groves depends not only on improving the yield of the mill and the corresponding revenues, but also on reducing cost and maximizing the oil production in the fruits, we have worked with a leading research institute to develop calibrations for Nitrogen, Phosphorous and Potassium in dried olive leaves. This knowledge is being used to control the fertilization for both timing and quantities. The speed of the NIR analysis allows us to perform such measurements at high frequency and on multiple parts of an orchard. This knowledge results in substantial savings by minimizing the use of fertilizers.

Last, but not least, due to our growing understanding of the relation between irrigation and oil production in the fruit, and because of the increasing cost of irrigation, the need to understand the degree of water stress in leaves led us to develop calibrations for two important parameters. These include the straightforward moisture in the leaves, and Turgor pressure, a measure used by scientists and growers to decide when and how much to irrigate. Turgor pressure measurement is a lengthy, complex and costly operation.

Once again, the speed and immediate availability of the Brimrose technology, which can be taken to the field to analyze leaves on the spot, is opening the door to huge benefits for farmers by reducing wasteful and ill-timed irrigation, while maximizing the oil production within the fruits.

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