Buch, Englisch, 208 Seiten, Paperback, Format (B × H): 148 mm x 210 mm, Gewicht: 349 g
Reihe: Elektrotechnik
Buch, Englisch, 208 Seiten, Paperback, Format (B × H): 148 mm x 210 mm, Gewicht: 349 g
Reihe: Elektrotechnik
ISBN: 978-3-8439-5634-5
Verlag: Dr. Hut
Lensless microscopy is a concept for portable, inexpensive and lightweight observation tools for investigating microscopic samples, especially in the life sciences, medical point-of-care and environmental analysis. Here, the influence of all the three main components of a lensless microscope: light source technology, image sensor, and reconstruction algorithm, on its performance are studied. This study performs various tests to determine the ideal level of coherence of the light source to produce a clear diffraction pattern with low speckle noise while being harmless for living cells. However, the wavelength of the light source and the distance between the object-to-sensor have a significant impact which limits the image resolution. Therefore, Fourier-based calculations are performed for image reconstruction to enable waveform back-propagation from the sensor plane to the object plane and transform the hologram into an image with better clarity and resolution. A number of new methods have been created during the development. First, the development and investigation of an autofocus and parfocal function were added to automatically reconstruct massive numbers of images produced during long-term measurements. By employing the non-uniformity of the intensity distribution as a statistical-based key figure for digital focusing, the lensless microscope can generate images with optimum sharpness automatically and perform focal-plane tracking of a moving sample in all three dimensions. Moreover, an improvement in image quality and information through a color reconstruction by implementing a multi-wavelength point light source is discussed. Additionally, a cutting-edge method for reducing the twin image caused by digital interference of various wavelengths is addressed and implemented. Finally, the implementation of a sub-pixel resolution approach are also investigated to point out and demonstrate approaches for increasing the resolution of lensless microscopy.
