Coherence-tailored lasers for biomedical imaging

When it comes to biological imaging using lasers, speckle comes into your images. Either to remove it, or to make use of it. Often times, you want to remove it. A frequently used way is to take many uncorrelated images sequentially with different illumination angles and then to average them. Engineering laser source itself may provide a better way. For instance, a VCSEL array that is composed of hundreds independent lasers can simultaneously illuminate the object and perform the average without sequential imaging, thereby achieve higher speed imaging compared with traditional way. We can also use speckle, because speckle contrast variation can be inferred to blood flow information. A laser that allows us to tailor the spatial coherence can achieve speckle free structural imaging and blood flow imaging almost at the same time.

• C Liu, H Cao, M Choma, "Coherent Artifact Suppression in Line-field Reflection Confocal Microscopy Using a Low Spatial Coherence Light Source", Optics Letters 41 (20), 4775-4778 (2016).

• S Knitter, C Liu, B Redding, MA Khokha, MA Choma, H Cao, "Coherence Switching of a Degenerate VECSEL for Multimodality Imaging", Optica 3 (4), 403-406 (2016). Featured in Optics & Photonics News, "Controlling Spatial Coherence" (2016)! Covered in Photonics, Phys.org, Optics.org, Wtnh, StreetInsider, OSA, Madgadget, YaleNews!