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projekte:dvdlsm:start

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Nächste Überarbeitung		Vorhergehende Überarbeitung
projekte:dvdlsm:start [2021/02/07 00:28] – [OPU Modification] thastiprojekte:dvdlsm:start [2021/02/07 22:25] (aktuell) – [Laser Diodes, Lens and Actuators] thasti
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 ~~NOTOC~~ ~~NOTOC~~
-====== DVD-Drive-Based Laser Scanning Microscope ====== +====== DVD-Drive based Laser Scanning Microscope ====== 
-{{ :projekte:dvdlsm:dvdlsm_full.jpg?400|}}+{{ :projekte:dvdlsm:dvdlsm_full.jpg?450|}}
  
 Due to an abundance of one specific type of DVD drives, plans were made to give a useful afterlife to these devices. A laser scanning microscope seemed to be the most useful project. Due to an abundance of one specific type of DVD drives, plans were made to give a useful afterlife to these devices. A laser scanning microscope seemed to be the most useful project.
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 ==== Laser Diodes, Lens and Actuators ==== ==== Laser Diodes, Lens and Actuators ====
-The OPU houses two laser diodes. As this is just a DVD/CD reader, the lasers are not very powerful but provide sufficient power for microscopic applications. The (red) DVD diode starts laser operation above approx. 60 mA and requires about 2-2.5 V of forward voltage. Its polarity can be easily determined by measurements.+The OPU houses two laser diodes. As this is just a DVD/CD reader, the lasers are not very powerful but provide sufficient power for microscopy applications. The (red) DVD diode starts laser operation above approx. 60 mA and requires about 2-2.5 V of forward voltage. Its polarity can be easily determined by measurements.
  
 The primary lens is positioned using electromagnetic actuators. These come in the form of three coils, which tilt or move the coil proportionally to the current flowing though them. Their polarity and required full-scale DC actuation current can be easily found by using a lab power supply. The primary lens is positioned using electromagnetic actuators. These come in the form of three coils, which tilt or move the coil proportionally to the current flowing though them. Their polarity and required full-scale DC actuation current can be easily found by using a lab power supply.
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 It was conjectured that the smaller inner quadrants were responsible for the low-sensitivity outputs, while the outer segments would produce a large amplitude (due to their larger light collection area). It was conjectured that the smaller inner quadrants were responsible for the low-sensitivity outputs, while the outer segments would produce a large amplitude (due to their larger light collection area).
  
-In a second reverse engineering session, the exact pinout was determined by means of selective illumination: For a given test, two IC output pins were compared using two DVMs, and an aperture was slowly moved along the surface, either vertically or horizontally. This would in a change of the output voltage for one of the outputs slightly earlier than for the other one. In this way, the positional relationships between all output pins could be resolved, forming a final assignment of diode quadrants to output pins.+In a second reverse engineering session, the exact pinout was determined by means of selective illumination: For a given test, two IC output pins were compared using two DVMs, and an aperture was slowly moved along the surface, either vertically or horizontally. This would in result a change of the output voltage for one of the outputs slightly earlier than for the other one. In this way, the positional relationships between all output pins could be resolved, forming a final assignment of diode quadrants to output pins.
  
 {{:projekte:dvdlsm:pinout_bg.png?800|}} {{:projekte:dvdlsm:pinout_bg.png?800|}}
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-Higher resoultion scan of the same device EPROM, scan area 500x500 um. The two routing layers can be seen above one another. (Picture Below)+Higher resolution scan of the same device EPROM, scan area 500x500 um (top right of previous image). The two routing layers can be seen above one another. (Picture Below)
  
 {{:projekte:dvdlsm:eprom_0p5x0p5mm.png?600|}} {{:projekte:dvdlsm:eprom_0p5x0p5mm.png?600|}}
  
  
-Scan of an I2C test chip from my colleage Szymon (fabricated in 65nm CMOS, picture below).+Scan of an I2C test chip from my colleague Szymon (fabricated in 65nm CMOS, picture below). Scan area 1x1mm.
  
 {{:projekte:dvdlsm:i2chip_first_scan_dt.jpg?600|}} {{:projekte:dvdlsm:i2chip_first_scan_dt.jpg?600|}}
  
-This picture shows some of the aforementioned nonlinearity in one axis, which introduces periodical distortions in the image. These could be corrected in principle, but I didn't bother. The nice CERN logo was placed on the top metal layer, and is composed of many small pixels that are on the order of a few micrometers large.+This picture shows some of the aforementioned nonlinearity in one axis, which introduces periodical distortions in the image. These could be corrected in principle, but I didn't bother. The nice CERN logo was placed on the top metal layer, and some of the lower level metals are actually already visible from the top (the vertical and horizontal power distribution stripes are placed on the two metal layers below).
  
 Also from this chip, here's a few very small scans performed at 200 nm step size. Small metal filling patterns on the top metal layer are imaged, each of which is only about a two micron wide square. Lithographic imperferfections can clearly resolved using this imaging technique. The horizontal (black) lines were caused by the erratic X-axis stage, sometimes going to places it was not told to go... Also from this chip, here's a few very small scans performed at 200 nm step size. Small metal filling patterns on the top metal layer are imaged, each of which is only about a two micron wide square. Lithographic imperferfections can clearly resolved using this imaging technique. The horizontal (black) lines were caused by the erratic X-axis stage, sometimes going to places it was not told to go...
  
 {{:projekte:dvdlsm:i2chip_fill_200nm.png?600|}}  {{:projekte:dvdlsm:i2chip_fill_200nm.png?600|}} 
 +
 +
 +Finally, here are two videos of the device in Action:
 +  * Focusing: https://youtu.be/iFzVEHeG0xE
 +  * Scanning: https://youtu.be/cj5zdhJTQUs
  
 ===== Summary ===== ===== Summary =====
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   * PC software: https://git.loetlabor-jena.de/dvdlaser/dvdlaser_sw   * PC software: https://git.loetlabor-jena.de/dvdlaser/dvdlaser_sw
  
- +===== References ===== 
 +I'm of course not the first one to build something like this. Here's some sources of my own inspiration: 
 +  * http://www.gaudi.ch/GaudiLabs/?page_id=652 
 +  * https://www.instructables.com/Laser-Scanning-Microscope/ 
 +  * https://pubs.acs.org/doi/10.1021/acssensors.8b00340 
 +  * https://www.researchgate.net/publication/321233124_Generating_SEL_and_SEU_with_a_class_1_laser_setup
  
  
projekte/dvdlsm/start.1612657689.txt.gz · Zuletzt geändert: 2021/02/07 00:28 von thasti
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