Tag Archives: Laser

Make Your Own Laser Scanning Microscope

A laser scanning microscope (LSM) is an optical imaging technique for increasing optical resolution and contrast of micrographs. It permits a wide range of qualitative and quantitative measurements on difficult samples, including topography mapping, extended depth of focus, and 3D visualization.

A laser microscope works by shining a beam of light on a subject in an X-Y plane. The intensity of the reflected light is then detected by a photoresistor (LDR) and recorded. When the various points of light are combined, you get an image.

Venkes had built his own DIY laser scanning microscope with a DVD pick-up, an Arduino Uno, a laser, and a LDR. He had also published an A-Z tutorial about making a similar device.

The result image consists of 256×256 pixels with resolution of 200 nm, about 1300 time enlargement, and it will not cost you a lot because you may have most of the parts. However, the scanning process is a bit slow, it may need half an hour for one image, and it is not crispy sharp.

The parts needed for this DIT LSM are:

  • 2 lens/coil parts of a laser pick-up (DVD and/or CD)
  • a bit of PCB
  • a piece if UTP cable (approx 15cm)
  • An Arduino UNO
  • An LDR
  • 2 x 10uF capacitors
  • 1 x 220 Ohm resistor
  • 1 x 10k resistor
  • 1 x 10k pot
  • 1 x 200 Ohm trim potentiometer
  • 1 breadboard
  • 1 switch
  • 1 3,5 mm jack plug
  • 1 audio amplifier
  • 1 laser with a good collimating lens
  • 1 piece of glass, a quarter of a microscope object glass or so to act as a semipermeable mirror
  • The under part of a ballpoint casing to put the LDR in

For the software side, an Arduino sketch is used to steer the lens, to read the LDR values, and to send information to a Processing sketch which will receive the data and translate it into an image.

You can find more details of this project with the source files at the project’s Instructables page. This video shows the device in action:

LASER TRIGGER FOR CHRONOGRAPH

I finished this laser wall trigger for my HIGH RESOLUTION AND ACCURACY CHRONOGRAPH. The purpose of this device is to generate the trigger start and stop impulses for my chronograph as soon as an object disrupts any of the laser beams.

LASER TRIGGER FOR CHRONOGRAPH – [Link]

Constant Current Laser Diode Driver Circuit Using OPA2350 OpAmp

The voltage-controlled current source circuit can be used to drive a constant current into a signal or pump laser diode. This simple linear driver provides a cleaner drive current into a laser diode than switching PWM drivers. The basic circuit is that of a Howland current pump with a current booster (Q1) on the output of a R-R CMOS OPA2350 op amp (U1). Laser diode current is sensed by differentially measuring the voltage drop across a shunt resistor (RSHUNT) in series with the laser diode. The output current is controlled by the input voltage (VIN) that comes from Trim pot PR1.

Features

  • Supply 3,3V DC
  • Load Up to 300mA
  • PR1 Trimpot Current Adjust

Constant Current Laser Diode Driver Circuit Using OPA2350 OpAmp – [Link]

RELATED POSTS

A Laser Treatment To Improve Paper Electronics

NanoEngineers” research group at Iowa University have been devoting efforts to use graphene and its amazing properties in their sensors and other technologies. Graphene has many extraordinary properties. It is about 100 times stronger than the strongest steel. It conducts heat and electricity efficiently and is nearly transparent.

Inspired by some recent projects about using inkjet printers to print multi-layer graphene circuits and electrodes, “NanoEngineers” have been working to move this research further by using the technology for a larger scale flexible, wearable and low-cost electronics. But there was some hurdles in improving the graphene conductivity after being printed and this process may damage the printing surface, such as papers, because of the high temperature or the use of chemicals.

Eventually, these engineers have led development of a laser-treatment process that allows them to use and improve printed graphene for electronic circuits and electrodes, even on paper and other fragile surfaces. The technology is said to show tremendous promise for a wide variety of fields including wearable sensors and thin film transistors with the ability of large-scale manufacturing.

It’s a three step process:

  • Graphene ink formulation: single layer graphene (SLG) powders were mixed with solvents and binders, bath sonicated, probe sonicated, and syringe filtered in order to produce a jettable graphene ink.
  • Inkjet Printing: The resultant graphene ink was syringed into the printer cartridge of a Dimatix Materials Printer and ejected via a piezoelectric nozzle in the subsequent printing process.
  • Laser Annealing:  A pulsed-laser processing of the electrodes using a Nd:Yag laser.
 Formulation, Printing, and Treatment, Source: <a href="http://pubs.rsc.org/en/Content/ArticleLanding/2016/NR/C6NR04310K#!divAbstract">Original Paper</a>
Formulation, Printing, and Treatment, Source: Original Paper

The engineers were able to remove ink binders and reduce graphene oxide by developing a computer-controlled laser technology that selectively irradiates inkjet-printed graphene oxide, Transforming the inkjet-printed graphene into a conductive material capable of being used in new applications is a huge breakthrough in nanotechnology.

More details are available at this paper on NanoScale journal.

Via:  ScienceDaily

Opto-isolated laser controller build

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Scott Harden built his own opto-isolated laser controller and wrote a post on his blog detailing its assembly:

My goal was to utilize a free hardware output line to signal to a device that I build to modulate the laser in a special way. This way there would be no modification to any existing equipment, and no software to install. Further, since this hardware isn’t mine, I don’t like the idea of permanently modifying it (or even risking breaking it by designing something which could damage it by connecting to it). The specific goal is to allow the existing software to cause the laser to fire 20 ms pulses at 15 Hz for a few dozen cycles of 5s on, 5s off. It’s also important to have some flexibility to reprogram this firing protocol in the future if a change is desired.

Opto-isolated laser controller build – [Link]

Arduino – Laser Tripwire Alarm System

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In this instructable, we will be building a laser guided tripwire alarm system using a SainSmart Leonardo R3 development board.

Arduino – Laser Tripwire Alarm System – [Link]

Quantum dots shrink on-chip lasers to 1μm

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by Julien Happich @ edn-europe.com

Published in Applied Physics Letters under the title “Sub-wavelength InAs quantum dot micro-disk lasers epitaxially grown on exact Si (001) substrates”, the findings from an international team of researchers opens a new route to CMOS-compatible on-chip laser integration.

The researchers designed subwavelength micro-disk lasers (MDLs) as small as 1μm in diameter on exact (001) silicon, using colloidal lithography (dispersing silica colloidal beads as hard masks before etching the prepared QD material layers). The disk region encapsulates five layers of InAs/InGaAs dot-in-a-well (DWELL) structure. The micro-cavity gain medium was grown on a high crystalline quality GaAs-on-V-grooved-Si template with no absorptive intermediate buffers. Under continuous-wave optical pumping (from an external diode laser operating at 532nm), the micro-disk structure lased in the 1.2μm wavelength range, with low thresholds down to 35μW at 10K (cryogenic temperature).

Quantum dots shrink on-chip lasers to 1μm – [Link]

‘Soldering’ with a laser

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Thijs Beckers @ elektormagazine.com writes about a new experimental method of connecting electronics components together using a laser beam.

Researchers from the University of Saarland have, together with colleagues from Helsinki, discovered a new material which can connect electronic components together using a chemical method. Multiple very thin layers (1000x thinner than a human heir) of aluminum and ruthenium are placed on top of each other. When an intense laser beam is pointed at it, a large amount of heat is released in the nanometer thin layer and a homogeneous layer of ruthenium-aluminide is formed.

This brief heat can reach a temperature of 2000 °C. With this, components close together can be connected to each other without the addition of solder. The ruthenium-aluminide forms a layer between the components, just like solder does.

‘Soldering’ with a laser – [Link]

Arduino – Processing Laser CNC Project

Neumi @ github.com has build an Arduino based CNC project and source files are provided.

This is my scratch build Laser CNC Engraver and PCB Exposer. It uses a 150mW 405nm laser diode and two CD drive motors and mechanics. A Processing sketch calculates the position of the pixels and send them to an Arduino Mega, wich drives the steppermotors. A TTL driver is used to control the Laser. With the joystick you can control the laser. You can set the exposure time, so you can engrave foam, paper, leather, plastic and wood. If you engrave photo-coated PCBs its possible to harden the surface and create your custom made PCBs.
The resolution is at about 100 pixels/cm. The work area is 3,2 x 3,2 cm.

Arduino – Processing Laser CNC Project – [Link]

Lasers built on silicon are a step towards fully integrated photonics

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image: spie.org

A group of researchers from the Cardiff University has demonstrated the first practical laser that has been grown directly on a silicon substrate. by Graham Prophet:

The lasing structure was formed in indium arsenide/gallium arsenide layers grown directly on a silicon substrate; the research group notes that previous work has involved wafer bonding techniques to merge electrical and optical (lasing) structures.

Lasers built on silicon are a step towards fully integrated photonics – [Link]