how did they measure light size?

[JustRegisteredNow]

"650 nanometers" like what? Did they just put a microscope and turn on anything with red light and measure it? also why is it 650nm when light can illuminate the entire room? as far as I'm concerned, it's infinity nanometers wide.

 

[ElectricPlasma]

650nm is the measurement of the wavelength of red light. It's the wavelength of every single photon emitted by the red light source, not the whole light output. This type of value is usually measured with something like a spectrometer.

https://en.wikipedia.org/wiki/Wavelength

 

[RedCowboy]

pssst Hey EP, justregisterednow may just be a troll

 

[Cyparagon]

Is that you, Agustus from wickedlasers forums?

 

[Encap]

Is that you, Agustus from wickedlasers forums?

Nice find Cyparogon--

Agustus lol.
Is amazing anyone could be so profoundly in the dark and be interested in lasers and light---both of them in case they are not one and the same.

 

[Gabe]

I always found it hard to convert from imperial light to metric light, I wish we would just standardize already. It makes it really hard to see when I visit the states.

 

[RB astro]

I always found it hard to convert from imperial light to metric light, I wish we would just standardize already. It makes it really hard to see when I visit the states.

:crackup:

 

[GSS]

:crackup:

Double that:crackup::crackup:

 

[Rivem]

Oh man. :crackup:

Just in case somebody wants to find out an actual answer, optical wavelengths are measured using interferometry. Basically, the interference properties of waves allow certain types of instruments to measure other properties like power over distance or light patterns to find wavelength. Look up wavemeters.

Math and comparison (with spectrometers) were used to find everything between the wavemeter measurements. That's why you only need a calibrated spectrometer to find a wavelength without measuring it. With more modern physics, we've also developed rules that say what wavelength certain amounts of energy and processes should produce. This is ultimately how laser devices are specified. Especially with diodes, there's a semiconductor bandgap which gives how much energy the light off of it can hold. Also, this is why there is a definite wavelength range that prevents very far UV LEDs and laser diodes.