光譜儀

製作過程及其理論

Seeing this picture , I think that we may rotate the grating so that the spectrum will form at the center.

Finally , we decided to rotate it to change the incident angle to 23 deg .

As expected , the diffracted visible light located at the center of the arc.

This is the draft of the spectrometer.

使用方法

Caution : Do not look at the sun directly

天文上的應用

If you look through a spectrometer , you may see some pattern like the photo in the previous page , this is called spectrum.

The first first kind is called emission spectrum, while the second is called absorption spectrum..

The last one is a continuum spectrum

Emission Spectrum Absorption Spectrum

Usually produced by thin gases.

e.g. Light bulb

Light passes through a cold, dilute gas .

e.g. Sunlight

Bright lines Dark lines

Each element has its own unique spectrum

Emission & Absorption

Here is the emission spectrum of some common elements.

You may find out all the spectra are different.

Hydrogen Helium

Argon

Mercury

The wave length of the diffracted light is indicated inside the spectrometer.

Since , it is easily to deduce whether we are looking at a emission spectrum or absorption spectrum,with the help of these data , we may know what elements the source contains.

光譜與恆星及其他天體

This is the graph which indicates the absorption spectrum of stars from the new-born one to the dead one.

Studying the spectrum of a star , we will obtain lots of information about it, for example , age , surface temperature, distance . Also ,we may get some information of celestial bodies around it.

Black Hole is an important discovery with the help of spectrum.

End

Created by Wu Kai Chiu