Technology Forum: SPIE Optics and Photonics Conference

From nanofabricated photonic materials to white LEDs to THz short pulse light sources, developments in the field of optics and photonics are happening at an astounding rate. And with the annual SPIE Optics and Photonics Conference approaching in August, the subject is more topical than ever.

Joining us for this discussion are Rob Morris, Ocean Optics; and Paul Gelsinger-Austin, Petra Lepke, and Samuel Sadoulet, Edmund Optics.

Everyone is talking about “green” technology and renewable energy these days. How has the use of nanomaterials in solar cells increased their ability to convert solar energy into electricity?

Morris: The name of the game in solar is dollars (or cost, if you will) per watt. The more cost efficiently that solar cells can be produced, the more likely the impact of solar as a renewal energy source is great. If it’s not economically viable, all the stimulus money in the world won’t save it.

The use of nanomaterials is all about making the cells more efficient. These materials typically enhance or replace a less efficient, more familiar technology or component – certain optical materials, for example, can be made to increase the amount of light reaching the solar-reactive area of the solar cell. Even if photonics suppliers are not involved in producing or using nanomaterials this way, they may reap the benefit of the need to monitor and analyze those materials.

How have developments in filter technology affected the field of optics, and particularly microscopy?

Morris: Every day there are advances that challenge our notions of the laws of physics. These cutting-edge developments encompass a wide range of areas. In microscopy, the technologies involved in imaging promise truly life-changing options for medical diagnostics and the life sciences. On a macro level, I can offer first-hand experience with the effect of improved imaging technologies: My cardiologist relies on fluorescence imaging technology to get a good picture of my heart as he ablates areas of arrhythmia during a recent procedure. Ablation is a technique used to mitigate or eliminate arrhythmias such as atrial fibrillation, which can increase the risk of stroke in many patients. The better the doctor can see into the heart, the more effectively he can guide the RF catheter used for ablation.

Gelsinger-Austin: Filters are pervasive throughout the field of optics, and are found in many optical devices and systems. From anti-reflection coated camera lenses to polarized sunglasses, filters are found anywhere a condition arises in which the amount of light propagating through a system needs to be controlled. Filter technology has evolved along with the need for better filters. The use of colored glass has long since been abandoned for microscopy techniques such as flow cytometry, confocal microscopy, and multiphoton microscopy, though colored glass can still be found frequently in machine vision applications where spectral tolerances are generally more forgiving. The current trend in filter manufacturing is to design dielectric filter stacks rather than bulk absorption filters, especially for microscopy applications. The benefits of using dielectric filters are found in improved transmission, better out-of-band rejection, customizable filter bands, and lower auto-fluorescence. Manufacturers are always trying to make better filters, and sputtering technology has been a boon to the filter designer as it allows more complex designs to be realized without having to sacrifice performance or durability.

Optics have come a long way since Galileo’s first astronomical use of the telescope 400 years ago (which is being celebrated at SPIE Optics & Photonics this year). Now there are a variety of space-based optical systems that are getting extensive use as the search for extrasolar planets intensifies. What are some of the challenges with these systems? Are there disadvantages to using space-based telescopes rather than ground-based systems?

Morris: I’m no expert in this area, but even I can imagine the challenge of making adjustments on a telescope here on earth compared with one in orbit in space. These are highly complex, very individualized systems that require delicate maneuvering.

There may be political considerations to space-based systems as well. I’m not immersed in this field so I can’t say for certain, but it’s not too hard to imagine that the specter of the Reagan-era “Star Wars” systems still affects certain decisions – not to mention the enormous costs of these telescopes. To some, the search for extra-solar planets may seem frivolous in light of other challenges right here at home.

Advances in optics have led to some of today’s most popular devices, such as cellular phone cameras with excellent image quality. What are some of the trends in optical technology development today? Where do you anticipate the most growth in optics? Why?

Morris:Although this isn’t particularly new, the interest in developing very application-specific optical devices is as high as it’s ever been. For example, it’s possible to use optical filter technology to make RGB color sensors that can report data back to an iPhone or iPod touch. That’s a simple three-wavelength device for a specific application. There’s no reason why that same technology couldn’t be applied to a host of other applications that require a limited number of wavelengths. That keeps costs down and now makes it possible to offer sensors at consumer-level pricing.

Lepke:Advancements in optics are happening on a variety of fronts – from developments of new materials, e.g. nanofabricated photonic material that creates a negative index of refraction, to new developments in light sources, such as white LEDs signaling an end of the fluorescent bulb, THz short pulse light source enabling imaging on nanoscale level, or high-power tunable light sources for fluorescence imaging. Detectors are another area of rapid developments; for example uncooled detector arrays resulted in decreased cost, size, and efficiency of thermal systems supporting the growth seen in commercial IR applications such as quality control and non-destructive testing, environmental sensing, medical and industrial thermography, law enforcement, fire fighting, and surveillance and IR spectroscopy.

The future demand for optical components and sub-assemblies will be sustained by strong growth of global markets in medical devices such as instrumentation for minimally invasive surgeries, diagnostic devices, and analytical instrumentation in applications (for instance, in-vitro and in-vivo diagnostics, DNA sequencing and PCR, flow cytometry, medical imaging including dental and bioimaging). Another factor will be sustained demand for spectroscopic methods combined with imaging technologies for the life science marketplace (pharma, biotech, food and agriculture testing), UV-VIS market driven by demand for micro volume instruments for biotech, environmental testing, and green technologies, and process spectroscopy for quality control will be the fastest growing segment.

Why?

Trends behind the profound growth in diagnostics and therapeutic medical devices driven by:

• Increase in aging population is driving demand for IVD devices worldwide.

• Chronic and infectious diseases are increasing globally.

• People becoming highly conscious of prevention of diseases.

• Healthcare becoming more accessible --> demand for various IVD devices

• IVD markets growing in emerging economies (India, China and Brazil)

• Strong growth for Market for HIV diagnostics (>33 MIL HIV infected people).

Important trend from visual systems to digital imaging influences designs of medical and analytical instruments, e.g., medical imaging systems employing x-rays has undoubtedly been propelled by the explosion of digital technology. The expanded role of imaging modalities in a whole host of clinical diagnostics applications from trauma to cancer to cardiology. (For supporting market data, please contact the editor.)

What is the biggest or most important advancement in the field of optics that you’ve seen in your career?

Morris:While marquee projects like the Hubble Telescope have captured everyone’s attention, to me the emergence of dichroic filters certainly ranks very high among optical advancements. Originally conceived for color lighting applications – the filters pass light of certain colors while reflecting others – these filters can be used for a host of applications. Multi-patterned arrays of different optical filters can be used in dense wavelength division multiplexers, micromechanical devices, and optical waveguide-based devices. Dichroics also can be applied to multi-part bonded filter applications common to the manufacture of digital data projectors and CCD camera detectors. Even newer opportunities involve improved LED color efficiency and multispectral imaging. It’s really very exciting stuff – and just the tip of the iceberg of what dichroic technologies have to offer.

Sadoulet and Lepke :Due to the prevalence of optically-based products in various markets, an optical design software has become a standard tool and part of a product design platform. The cross-disciplinary engineering teams, often consisting of mechanical, structural, electrical, and optical and bioengineers, allow an integration of different segments of product development and automation of an engineering cycle supporting an ongoing trend in collaborative design. Since optics has been an enabling technology for a variety of product platforms including optically-based diagnostic instrumentation such as blood analyzers, DNA sequencers, or microplate readers, mechanical designers using CAD software or bioengineers proving the new concept are often required to provide simple optical layout or incorporate optical elements into the system before passing the file or concept to an optical designer for deeper analysis and performance optimization. The ongoing trend was a compelling reason for optical design software developers to introduce a software linking CAD with optical design software, enabling a smooth transition of design files.

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