Digital Artifacts

nixcraft:

I would love to change the world, but they won’t give me the source code.

Unknown

fuckyeahphysica:

A couple of weeks ago, we discussed about the famous Photograph-51 and how that led to the discovery of the Double Helix structure of DNA.

We mentioned in that post that the best way to visualize that diffraction pattern is by using a laser and pointing it on a helix from a ballpoint pen.

And in the previous post on pixels, we learned about how the RGB pixels arranged on a screen come together to render those beautiful images on your screen.

                                        Source : Microworld

The pixel arrangement on a screen need not be periodic like shown above. In fact ,most manufacturers have their own unique type of representation ( see below )and the type varies with the type of application as well.

As an amateur physicist you do not have a microscope but only a green laser as your tool, how would you go about finding which one of these arrangement your smartphone has ?

Visualizing pixel spacing using a LASER

For a fact, you know that:

if you shine a red light on a green or blue object, it will appear black.

                                              Source    

So if you take your green laser pointer and shine it on any of those pixel blocks, you know that you are only going to get green light from the green filter.

The other two filters will absorb the green light.

And using that you can find out the type of pixel arrangement your smartphone has.

We will be testing it out with Samsung Galaxy S4 whose  pixel arrangement on the screen looks like so:

Notice the oval nature of the green dots.

Let’s shine a green laser on the screen observe the resulting diffraction  pattern:

The diffraction pattern that you obtain is the following:

Observe that the dots on the image are not circles but ovals instead. This is due to the nature of the pixel arrangement on the Galaxy S4.

If you had a good red laser (which we did not) and tried this same experiment, you would get a pattern like so:

You are also welcome to try it on a smartphone of your choice or any electronic display and compare it with the pixel arrangement of that particular device.

This paper (from which the above image has been taken) runs through some more examples of the diffraction pattern that one obtains from common electronic components.

Have fun!

Related Interesting videos:

LCD Technology: How it Works

How a TV Works in Slow Motion - The Slow Mo Guys

* As with any diffraction pattern, you can measure the distance between the two dots and calculate the distance between two consequent pixels using the wavelength of the light source as given.