0
$\begingroup$

So we can modify light outside of the visible spectrum via sophisticated lenses with the result being a new frequency inside the visible spectrum.

What I would like to do is different. I would like to explore (with my eyes) the edges of the visible spectrum i.e. red and violet. Ideally, I would love to have a light bulb, which emits light of any frequency required. That way I will make it red, and then decrease the frequency until it becomes invisible. That is, I am curious how sharp is the drop-off in our eyes' transfer function with frequency.

Trouble is, I don't have any laboratory equipment. All I have is an oscilloscope, breadboard and basic knowledge of controlling LEDs.

Is this feasible? I would expect a compromise solution as well, e.g. wait for a rainbow and look at it's edges.

$\endgroup$
  • 1
    $\begingroup$ Those aren't "lenses" which cause frequency conversion. Meanwhile, you need to learn about black-body curves, wavelength distribution from LEDs, and so on before asking a question like this. $\endgroup$ – Carl Witthoft Nov 21 '15 at 15:13
1
$\begingroup$

Take a light-source spreading over the visible spectrum (e.g. light bulb, sun light) and decompose this light with a prism. You can as well wait for the next rainbow or make it yourself on a sunny day.

$\endgroup$
  • $\begingroup$ And how would he know whether he can't see a given $\lambda$ or it just isn't there, or isn't bright enough? $\endgroup$ – Carl Witthoft Nov 21 '15 at 15:14
  • $\begingroup$ In UV, you could use some fluorescent material like bleached paper. In IR it is less critical when you use a black-body source (sunlight, light bulb), there is probably enough power. $\endgroup$ – Timeless Nov 21 '15 at 16:30
1
$\begingroup$

Can I see the edges of the visible spectrum at home?

The edges of the visible spectrum do not exist. They are like the edges of the audible spectrum which you can try to find using this Online Tone Generator. Can you identify with precision the lowest and the highest frequency you are able to hear?

$\endgroup$
  • $\begingroup$ Indeed a similar experiment. However, either this noise generator is not functioning correctly, or my system of braowser-wireing-amplifier-speakers is not, because at max volume, I can hear 1Hz (as a pulse about once a second). $\endgroup$ – Vorac Nov 21 '15 at 13:57
  • $\begingroup$ @Vorac no, you cannot hear 1Hz sine wave. You can sense a strong pulse, and a pulse if not sinusoidal will contain a lot of harmonics in the audible range. $\endgroup$ – Carl Witthoft Nov 21 '15 at 15:15

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.