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Holoscope – Lensless Microscope – PART 3: Components and Sony XPERIA Z1 Camera disassembly

A project log for Holoscope - Superresolution Holographic Microscope

Subpixel imaging using the Raspberry Pi and an Android Smarthpone. The lightsource is represented by an LCD.

beniroquaibeniroquai 05/20/2016 at 17:140 Comments

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Efficiency of the coupling:

There are some losses which have to be taken into account. Geometrical losses for example which results from the power which doesn’t go into the fibre: diameter of fibre < Source. Then Fresnel losses which equals tot he power which is lost du to radiation and reflection. Etendue ..

LED-Specs

Fiber-specs

Setup of coupling an darranging the fibers

Alternative: Projektor – DMD/DLP-Technologie

The projector used is an old Optoma Pico PK 101 – LED-Projektor with an DLP-Chip at 480×320 px. And 0.3-Inch (7.62 mm)

Principle and Setup of the new illumination system with the DLP

Mixing the colours either by a colour wheel or PWM driven RGB LEDs which causes a heavy interference over time. That’s probably one of the major drawbacks of this system! The projector was then modified by putting a high power LED with a specific wavelength peak for fluorescent probes (GFP at 450nm – royal blue)


Camera

LOGITECH WEBCAM

The first version of the Holoscope used an old webcam with a 720p, ca. 1.3 MP chip. The pixelsize was estimated with 3µm. The Webcam has a USB-connector which goes straigth into the smartphone. Most of the newer smartphones are capable to drive those as an USB – on the go device. Webcam drivers are available on github. This soloution was quiet nice though, but the resolution is not good enough.

SONY XPERIA Z1

A used Sony XPERIA Z1 Smartphone with a cracked screen for a reasonable price has one of the best cameras in todays smartphones. The camera itself has a large 1/3,06 inches sensor at 20 megapixels. This results in pixelsizes of 1,12 µm. Smal! When disassembling the lens module one can be astonished that the entire module costs just 20 Euro. Engineering-power at a glance. The clear-aperture has a value of F2.2 at a focal length of 28mm at 35mm FILM equivalent.

A good side-effect is, that the software which will reconstruct the object can run on the smartphone itself. It has a quad-core with an OpenCL driven GPU. A powerhouse for less than 100 Euro..

Another awesome aspect is, that ANDROID devices are able to drive MHL-devices which is the mobile standard for HDMI. The DMD-projector has a VGA port. So you need the following que:

Smartphone -> MHL-cable (which has a HDMI-port) -> HDMI-VGA-adapter -> projector.

Funny thing: It won’t work out of the box, because the max. resolution of the projector is less than the standard MHL-resolution of the Sony. Can’t remember how, but I figured out, that when pressing #*#*SERVICE*#*# (Service in T9-numbers) in the dialer – the service menu opens. Under settings, one can set up the MHL resolution. Tadah. It works.. when rebooting it always forgets this setting, so one need to reset it.

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