Low-cost, high-speed near infrared reflectance confocal microscope.

We have developed a low-cost, near-infrared (NIR) reflectance confocal microscope (RCM) to overcome challenges in the imaging depth and speed found in our previously-reported smartphone confocal microscope. In the new NIR RCM device, we have used 840 nm superluminescent LED (sLED) to increase the tissue imaging depth and speed. A new confocal detection optics has been developed to maintain high lateral resolution even when a relatively large slit width was used. The material cost of the NIR RCM device was still low, $5,200. The lateral resolution was 1.1 µm and 1.3 µm along the vertical and horizontal directions, respectively. Axial resolution was measured as 11.2 µm. confocal images of human forearm skin obtained at the imaging speed of 203 frames/sec clearly visualized characteristic epidermal and dermal cellular features of the human skin.