Laser-Based Mid-Infrared Microscopy

Interview conducted by Alexander ChiltonSep 26 2014

Matthew Barre, Business Development Manager at Daylight Solutions, talks to AZoM about the advantages and applications of the new Spero Infrared Microscope.

Could you provide our readers with an overview of the history of Daylight Solutions and the markets within which you operate?

Daylight Solutions was founded in January 2005 by three high tech entrepreneurs. Today the company consists of 60 people who share a vision of developing and advancing breakthrough technologies and products that benefit society in meaningful ways. Since its inception, Daylight Solutions has differentiated itself by delivering unique and highly advanced “Best in Class” products and services.

Daylight Solutions’ molecular detection and imaging products consist primarily of lasers, sensors, and imaging systems, all of which leverage the company’s mid-infrared, quantum cascade laser (QCL) technology. This core technology provides a versatile platform from which new products are developed, allowing the company to serve Scientific Research, Defense, and Commercial markets.

The company is committed to innovation and introduced the world’s first broadly tunable mid-infrared laser system for scientific research, the world’s first semiconductor-based laser for protecting aircraft against shoulder-fired missiles, and most recently Spero, the world’s first mid-infrared laser-based microscope for real-time biochemical imaging and material analysis.

Daylight Solutions is ISO-9001 certified and possesses advanced manufacturing capabilities.

With a long list of patents, best in class performance, and many innovation awards to its credit, Daylight Solutions is considered the world leader in mid-infrared molecular detection and imaging.

You mentioned the recent launch of Spero, a laser-based infrared microscopy platform – could you talk our readers through its main features?

Spero is the world’s first mid-infrared microscope to utilize a tunable laser illumination source.  We’ve leveraged our expertise in broadly tunable QCL technology to provide a chemical imaging microscope that outperforms traditional FTIR microscopes in standard metrics such as optical resolution, field of view, and data acquisition time. Spero also eliminates the sample damage and fluorescence issues that are common with Raman microscopy.

The microscope provides diffraction-limited optical resolution and high signal-to-noise spectral data across the entire mid-infrared fingerprint region, from 900 cm-1 to 1800 cm-1 (5.5 µm to 11.0 µm).  The instrument includes two infrared objectives: a 12.5X objective with a 650 µm field of view and a 4.0X objective with a 2.0 mm field of view.  These objectives provide a unique combination of high spatial resolution with large area coverage.  The microscope also includes a 12.5X visible objective with a 650 µm field of view that is matched to the high magnification infrared objective.

Spero supports both transmission and reflection measurements, includes a high-precision automated stage, and ships with ChemVision, a powerful and user-friendly software suite for data acquisition and hyperspectral image visualization.

What are the main advantages of Spero from a performance point of view?

Spero provides three main advantages over traditional infrared microscopes.  First, it provides diffraction-limited spatial resolution across the entire tuning range of the instrument.  This is enabled by the very high spectral brightness of the QCL illumination source.  Second, this high spatial resolution is coupled with very large field of view objectives.  With existing instruments, one typically has to sacrifice area coverage to achieve diffraction-limited spatial resolution.  And third, Spero generates hyperspectral data cubes very rapidly.  A high-resolution, full spectrum data cube from 900 cm-1 to 1800 cm-1 with 4 cm-1 spectral resolution can be collected in only 5 minutes.

How easy is Spero to use?  Does it have any features which make it particularly user-friendly?

The ChemVison software suite was developed from the ground up at Daylight Solutions and was specifically built for the Spero microscope.  It utilizes a “context aware” paradigm, meaning that only the options that are available in the current context are presented to the user.  This helps to reduce clutter and avoids unnecessary menus, windows, pop-ups, etc.  The software includes very user-friendly tools for live imaging, snapshots, and movies.  It also includes features for automated mapping and batch data collections for unattended operation.

The only connections to the instrument are power and communications to the PC.  A purge line is available for dry air or nitrogen to eliminate absorption effects from atmospheric moisture.  The microscope also utilizes uncooled camera technology so no liquid nitrogen or cool down time is required.  This is a big benefit for overall convenience, extended data collections, and total cost of ownership.

What are the key industrial design features of Spero which set it apart from its competitors?

We designed Spero to be familiar to analytical instrument users while also utilizing simple and accessible design cues from modern consumer products.  This simplicity carries over into the software as well.

Our goal was to create a compact, desktop instrument that, coupled with our breakthrough technical performance, could enable mid-infrared chemical imaging in applications that may not have been practical with existing infrared microscopes.  For example, in the Life Sciences space, FTIR imaging has not been feasible in clinical settings due to the space requirements of the Michelson interferometer, the requirement for liquid nitrogen cooling, and also the relatively long data acquisition times.  We’ve addressed all of these limitations with the Spero microscope.

Does Spero have any new imaging modalities?

Yes, the microscope provides two entirely new imaging modalities that simply aren’t possible with existing instruments.  The first, Live Imaging, provides the user with a live image of a sample illuminated at a discrete mid-infrared frequency.  This allows for real-time visualization of specific absorbance features in complex, non-homogenous samples.  The second, Sparse Data Collection, allows a user to program any set of mid-infrared frequencies to collect into a hyperspectral data cube.  This enables specific absorbance features to be probed while ignoring other spectral regions that may not be of use.  And of course, this results in extremely rapid data acquisition times, less than 1 minute for roughly 40 frequencies or less.  And again, this type of discrete frequency imaging, enabled by our tunable laser source, just isn’t possible with FTIR microscopes.

Could you summarise the recent research which was carried out using Spero by the University of Manchester in conjunction with Daylight Solutions on the imaging of tissue micro arrays?

Dr. Peter Gardner and his colleagues at the University of Manchester recently used Spero to rapidly image a set of 200 breast cancer samples on a tissue micro array.  In short, they were able to collect a large area mosaic with Spero in 9 minutes and it took 19 hours to collect a comparable mosaic with their high-end imaging FTIR microscope.

The full publication in Analyst is available here:

http://pubs.rsc.org/en/content/articlelanding/2014/an/c4an00638k#!divAbstract

How can Spero be used to analyse materials and polymers?

Analysis typically begins with preparation of a relatively thin (5 µm to 10 µm) section for transmission measurements or simple surface preparation for reflection measurements.  A large area map can quickly be generated with either the visible objective or at a single frequency with one of the infrared objectives.  Once an area of interest is identified, either a full or sparse hyperspectral data cube can be collected for spectral analysis or offline spectral library matching.

As an example, we recently worked with a large semiconductor manufacturing company to help identify defects and voids at a subsurface interface between a copper substrate and an organic film.  With mid-infrared illumination, we could penetrate the upper organic layers and clearly identify voids as well as chemically identify contaminants.

You also recently collaborated with researchers at the University of Central Lancashire and the University of Strathclyde to investigate how mid-infrared spectroscopic imaging can be used to image tissues and biofluids.  Could you provide our readers with a brief summary of the study and some information on how Spero can be used in biomedical research applications more generally?

This work was conducted with Dr. Matt Baker and his colleagues and included a comparison of spatial resolution between Spero and an imaging FTIR for brain cancer tissue, highlighting the diffraction-limited spatial resolution achieved with Spero.  The second part of the paper was focused on Spero’s Sparse Data Collection mode using multiple blood serum samples.  The results show that complete and automated segmentation of cancerous and non-cancerous blood serum was achieved using only 14 discrete mid-infrared frequencies.  This data can be collected in less than a minute.  Follow on studies are now underway to explore high-throughput screening protocols with multiple micro-droplets within a single field of view.

This is a good example of how Spero is being utilized to support biomedical research in a variety of applications.  The high spatial resolution and rapid spectral data acquisition can support evaluation and characterization in the preliminary stages of a study.  Once the pertinent spectral features are identified, sparse collection methods can be explored and optimized to support rapid data acquisition for larger scale trials.

Can Spero be used for practical applications in any other fields of research and study?

Spero can be used for a wide variety of chemical imaging applications.  In addition to the applications mentioned above, pharmaceutical analysis, forensics, and food inspection are all ideally suited for the instrument.

Where can our readers find out more information about Spero and Daylight Solutions more generally?

Information on Daylight Solutions products and services, including Spero as well as our full line of broadly tunable laser sources can be found at: www.daylightsolutions.com

About Matt Barre

Matthew Barre joined Daylight Solutions in 2010 and is currently leading the business development efforts for the Commercial Business Unit.  Prior to joining Daylight Solutions, Mr. Barre held several program management and business development positions at General Atomics, producing imaging and optical sensor systems for unmanned aircraft.  Mr. Barre holds a B.S. in Mechanical Engineering from the University of California at Santa Barbara and a M.S. in Mechanical Engineering from Stanford University.