A basic Raman spectroscopy assembly delivers simple information. However, if you are working in biomedical and bio-analytical applications, advanced Raman filters are needed.
Advanced Raman filters can be utilized in Raman spectroscopy applications to transmit real-time data on biological tissue. These filters have huge application potential in medicine, research, and biomedical engineering, and can be modified to be used in a wide range of different applications.
Recent progress in Raman spectroscopy results from employing precise configurations and carefully chosen filters to optimize the amount of information this technique can deliver. Determining the appropriate laser wavelength and the ideal filter will vary across different types of biological samples, so it is crucial to carry out proper research and identify what parameters are suitable for a given application.
How does Raman spectroscopy work?
Raman spectroscopy is performed by lighting up a sample with a laser beam and monitoring the resulting scattered radiation. This scattered light can be classified into two sets: Rayleigh scattering at the laser wavelength and inelastic scattered light.
The inelastic scattered light reveals certain details about the sample, but the Rayleigh scattering generates much higher intensities. To separate the Rayleigh scattering from the inelastically scattered light and the Raman signal, a laser blocking filter (either a notch filter, edge pass filter, or bandpass filter) can be used.
Image Credit: Avantier Inc.
Determining what this scattered light is and how it can affect human health is a central question. Known as Raman scattering, a good signal reveals what molecules are present in a sample and even what the intermolecular bonds look like.
Historically, holographic gratings and multiple dispersion stages were required to filter out the Raman scattering, which then might be gathered using photomultipliers. Today, notch or edge filters are the preferred choice to ensure unwanted Rayleigh scatter is eliminated to provide a clear signal.
This article presents two real-world case studies of advanced spectroscopy in action in the biomedical sciences: one in real-time neurosurgery and another that offers medical practitioners and researchers a deeper understanding of the process and progression of osteoporosis.
Raman spectroscopy for real-time tissue analysis in neurosurgery
Raman spectroscopy is nondestructive and produces results in real-time. It can be used to view tissue at the surface but also provides a chemical fingerprint of cells many layers deep. This makes the method perfect for real-time tissue analysis and visualization during neurosurgery, the ‘visual eye’ that guides the knife.
After the bulk of a tumor is removed, a small number of cancerous cells known as a residual tumor remain. This is considered to be one of the leading causes of neurosurgery failures. Thus, it is vital to readily differentiate between healthy and cancerous tissue while performing surgery.
Raman spectroscopy has the application potential to do this, as it can differentiate between healthy tissue, pathological tumors, and necrosis. Raman techniques like CRS, CARS, or SRS microscopy can provide a stronger signal and quicker imaging times.
Raman spectroscopy for osteoporosis diagnosis
Osteoporosis diagnosis is another area in which Raman spectroscopy demonstrates promise. Osteoporosis is a condition that reduces bone quality by compromising bone fragility and low BMD, but until recently, no medical diagnostic method has been used to evaluate the bone quality of a living subject.
Testing on mice has revealed that Raman spectroscopy can offer a real-time view of the changes in carbonate/phosphate ratio and mineral/matrix ratios that occur when osteoporosis sets in. Soon, these techniques could enable a deeper understanding of how osteoporosis impacts human health and how biomedical sciences can reverse or stop bone deterioration.
Raman spectroscopy can be used to gauge bone density and bone quality, critical markers of osteoporosis. Image Credit: Avantier Inc.
Selecting optimal optical filters for your application
Avantier is a manufacturer of custom Raman edge filters, Bandpass filters, and notch filters that have been optimized for blocking the laser line and transmitting anti-stokes Raman scattering. Avantier also offers laser line filters; these filters relay the exact wavelength of laser light required to illuminate the sample while preventing the passing of other radiation that could lead to deterioration in the signal-to-noise ratio.
Avantier's engineers and designers are available for consultation and can help advise and determine the optimal wavelength ranges, optical density, and type of filter for a given application. Avantier will also work with clients to identify the ideal configuration and angle of incidence for a system.
About Avantier Inc.
Avantier Inc. is an unparalleled leader in providing imaging systems solutions and optical solutions.
They offer advanced precision custom optical design, optical engineering, optical lens assembly, rapid optical proto-typing, image processing and manufacturing services.
Avantier is ISO 9001:2015, ISO 13485:2016, and ISO 14001:2015 certified.
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