In my high school physics class we measured the pitch between the tracks of a CD using the same principle. You just need a light source with a known wavelength, like a laser. It was a pretty cool experiment!
That sounds a fun project :) I tried a little peeling of a CD-R under a microscope, where can see the tracks, I should try and measure the pixel distance and convert to track width - https://www.anfractuosity.com/files/cd-r.JPG
what microscope are you using? i've been itching to get into microscope photography for a new hobby, but because i know myself, it'll be a fun but expensive rabbit hole. i've been deliberately putting off on researching because i also know myself and will be just as likely to be shopping than researching
It's an Olympus BHM that I got cheaply from ebay. It's a trinocular metallurgical microscope, that I added an old SLR to, for that photo. I noticed the semi-silvered mirror seems rather scratch though, so might need to look at replacing that.
are you attaching the camera directly with an adapter, or is it projecting on to whatever lens you are using? i guess i'm coming at this thinking of it in terms of astrophotography using T-adapters to connect in place of on eyepiece vs taking an image from the eyepiece
In the trinocular port, there's an eyepiece, which I forget the magnification of afraid. And to that port I added this - https://www.alanwood.net/olympus/photomicro-adapter-l.html and then used an OM to EF mount converter, which the Canon camera directly attached to.
I've since bought a microscope imager, that provides an output over USB. But I think I need to remove the OM converter, and get a shorter adapter to successfully attach to the microscope C-Mount.
Either works, but trust me, the trinocular part is far superior, ergonomically. You do need to know whether you want a metalurgical scope or a compound light transmission scope. The former is good at looking at opaque samples, the latter for transparent samples (biological stuff mostly).
that is something i have considered, but not known what terms to use to look it up. i would love to be able to look at opaque things in a highly magnified way, so the lighting issue is something i had in the back of mind. i do like the biological stuff in hopes of possible timelapse to show growth.
This is an awesome picture! Forgive me if this is a stupid question but are we seeing 0s and 1s here? Is that what the black is? Kind of the equivalent to a morse code dit (0) and dah (1)?
That not a stupid question. It's a bit (ha!) more complex. These are called pits and lands.
> The pits and lands do not directly represent the 0s and 1s of binary data. Instead, non-return-to-zero, inverted encoding is used: a change from either pit to land or land to pit indicates a 1, while no change indicates a series of 0s. There must be at least two, and no more than ten 0s between each 1, which is defined by the length of the pit. This, in turn, is decoded by reversing the eight-to-fourteen modulation used in mastering the disc, and then reversing the cross-interleaved Reed–Solomon coding, finally revealing the raw data stored on the disc.
These encoding types are used to improve the "tracking" of the laser head, and to keep the timing consistent. We want the medium to regularly have changes between pits and lands to synchronise the timing and speed of the disc. The encoding scheme enforces this.