Abstract
Based on partially-coherent digital in-line holography, we report a field-portable microscope that can render lensfree colour images over a wide field-of-view of e.g., >20 mm2. This computational holographic microscope weighs less than 145 grams with dimensions smaller than 17×6×5 cm, making it especially suitable for field settings and point-of-care use. In this lensfree imaging design, we merged a colorization algorithm with a source shifting based multi-height pixel super-resolution technique to mitigate ‘rainbow’ like colour artefacts that are typical in holographic imaging. This image processing scheme is based on transforming the colour components of an RGB image into YUV colour space, which separates colour information from brightness component of an image. The resolution of our super-resolution colour microscope was characterized using a USAF test chart to confirm sub-micron spatial resolution, even for reconstructions that employ multi-height phase recovery to handle dense and connected objects. To further demonstrate the performance of this colour microscope Papanicolaou (Pap) smears were also successfully imaged. This field-portable and wide-field computational colour microscope could be useful for tele-medicine applications in resource poor settings.
Highlights
In recent years there has been a large interest in point of care (POC) imaging and sensing devices that could permit remote clinics or doctors’ offices to conduct basic diagnostic tests that are traditionally restricted to hospitals, requiring a relatively large capital investment [1,2,3,4,5,6,7,8,9,10]
These computational microscopes do not use any lenses between the object and the image sensor chip, where the object is placed in close proximity (, 0.1–1 mm) to the active area of the sensor chip
Colour has a psychological effect since cytotechnologists, pathologists and physicians are in general trained to observe specimen in colour. To address this challenge for holographic on-chip microscopy, here we present a lensfree super-resolution colour microscope design, which is cost-effective and field-portable, weighing, 145 grams with dimensions of, 176665 cm. In this fieldportable colour microscope, we introduce an image processing technique that mitigates ‘rainbow’ like colour artefacts that are characteristic of digital holography [43,44,45,46,47]
Summary
In recent years there has been a large interest in point of care (POC) imaging and sensing devices that could permit remote clinics or doctors’ offices to conduct basic diagnostic tests that are traditionally restricted to hospitals, requiring a relatively large capital investment [1,2,3,4,5,6,7,8,9,10]. Lensfree holographic on-chip microscopes form an emerging sub-group of such POC imaging devices, and of digital holography in general [20,21,22,23,24,25,26,27,28,29,30,31], offering competitive alternatives to conventional lens-based microscopes, with several key advantages such as wide field-of-view (FOV) and large depth-of-field, yielding gigapixel range phase and amplitude images, in addition to compactness and cost-effectiveness, making them especially appealing for global health related applications [32,33,34,35] These computational microscopes do not use any lenses between the object and the image sensor chip, where the object is placed in close proximity (, 0.1–1 mm) to the active area of the sensor chip. An additional advantage of these holographic on-chip microscopes is that the recorded image can be digitally focused to different depths, allowing screening of large sample volumes [38,39,40]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
