Broadband Light Source — OCT a High-end Imaging Technology?

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OCT (Optical Coherence Tomography) is a rapidly evolving imaging technique that has significantly changed the ophthalmology practice in a better way. It is a non-invasive, diagnostic imaging technique that generates cross-sectional images of retinal tissues.

In particular, there are two primary techniques for OCT. The first and the latest technique is called- spectral domain optical coherence tomography (SD-OCT) or the Fourier domain OCT, which uses the broadband light source. And the other one is the traditional way called- time domain optical coherence tomography (TD-OCT).

In the later sections, we will understand how SD-OCT is superior to traditional TD-OCT and what are the advantages of SD-OCT over TD-OCT.

How Broadband Light Source-based SD-OCT is Superior to TD-OCT?

Invented in the year 2001, spectral domain OCT is the latest type of OCT that incorporates broadband light source and spectrometer to measure and maintain the reading. In a very short span of time, spectral domain OCT has become indispensable for researches, diagnosing, monitoring, and screening various diseases related to the macula and optic nerve head.

As we know, OCT is a technology that uses the principle of indirect interferometry. According to this principle, a beam of light is directed into the eye's retina. The resulting reflected light is detected by the detector, which is then compared to the reference light beam to measure the light's echo time delay.

This principle remains the same in both- the broadband light source-based SD-OCT and the traditional technique called TD-OCT. However, the significant difference between these two technologies is the reference beam placement and signal acquisition technique. 

In time domain OCT, the information is obtained from the reference mirror, which moves mechanically. Whereas, in broadband light source-based spectral domain OCT, the reference mirror is stationary. The reflected light's resultant interference pattern is split by a grating which undergoes Fourier transformation to measure every echo time delay simultaneously.

Broadband Light Source Modules



Broadband Light Source Desktop


Benefits of Using Broadband Light Source-based Spectral Domain OCT

There are several benefits associated with using a broadband light source based SD-OCT. Unlike time domain OCT, spectral domain OCT offers a significantly high scanning speed, which enables it to generate a quality cross-sectional image of the retina behind the thick surface.

Besides, because of the stationary reference arm, SD-OCT also offers high acquisition speed compared to TD-OCT. The commercial availability of the superluminescent light diode-based SD-OCT makes them able to extract data exceptionally quicker than the TD-OCT. i.e., approximately 50-100 times faster.

Also, the broadband light source based SD-OCT provides data about the retina that could be linked with glaucoma and other retina diseases. Using commercially available SD-OCT, one can also gauze the health of retinal tissue and diagnosis it in a better way.

Moreover, the higher resolution of almost 5 to 7 micrometre of SD-OCT can generate images of subtle abnormalities that are not visible with time domain optical coherence tomography. Along with images, it also offers improved segmentation and higher accuracy in the retinal layer's measurement.

Looking at all these advantages & abilities associated with broadband light source-based SD-OCT, it is certain that the technology is here to stay for a long time, especially in the clinical realm.

Inphenix is a US-based broadband light sources & laser manufacturer that offers a large range of distributed feedback lasers, VCSELs, and swept source lasers among others. Each of their SLD modules is plug-and-play and are easily mountable, making them the perfect choice for OEM integration. Check out their website for more information.

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