This is the last – and hopefully last – concept, how a portable lensless microscope, using only opensource and cheap components could look like. It holds all necessary parts. The Raspi as the sychonisation for image acquisition and hardware controle as well as a server for pushing the images taking with the PiCamera to the handheld device. The CPU/GPU of the Pi is not strong enough to decode the images, therefore a smartphone acts as a viewfinder and image-processor
In order to recover phase, it’s a good way to capture images from illuminated from multiple angles and at multiple Z-distances. An IFTA (Iterative Fourier Transfrer Algorithm) can, by back and forthpropagating the electric magnetic field (amplitude and phase) converge the phase – will explain this soon.
Therefore an old zoom lens acts as the Z-stage. It’s precise enough to move the object. A used linear-stage from ebay gives requiered robustness
In order to shift the object on the sensor, to get sub-pixel-resolution, a collimated high power led is illuminating the LCD whichs backlight is removed. By witching on/off several pixel patterns, each pixel acts as a point-source and thus forms a ~spherical wave – the reference wave. Shifting the pixels, also shifts the sperical wave which follows in a shift of the object on the sensor.
The drawings are made with Autodesk Inventor 2015 and will be uploaded to the GITHUB repository. They have been 3D printed with PLA material. It works!