Current Trends in Digital Imaging for Optical Microscopy

Abstract

Digital imaging has provided a number of possibilities in optical microscopy which can not be achieved easily by traditional methods. These include the possibility of low-light imaging, ease of image manipulation (processing and analysis) and transmission via electronic communication channels. Recently, digital imaging has become the buzz-word in photography. Therefore, it is the intent of this article to evaluate the current state of digital imaging technologies for optical microscopy, both pro and con.There are certain applications where digital imaging is the only feasible way to gather image data, examples include laser scanning confocal microscopy and low-light CCD microscopy. Based on the nature of image acquisition methods, one can classify digital imaging into two major domains: (1) sequential and (2) parallel data acquisition. The sequential data acquisition method is generally used in scanning devices such as the confocal laser scanning microscopes (CLSM). Photomultipliers and solid state devices are generally used as the photon detector(s) and the analog signals are subsequently digitized. On the other hand, the use of 2D array detectors such as CCDs falls into the parallel acquisition category. Although, the data from a CCD is read-out sequentially, all the pixels on a CCD chip acquire the image simultaneously. Depending on the dynamic range of the photon detector and needs of the application, the digitized image generally has a dynamic range of 8, 12 or 16 bits.