How to make doppler laser cooling?

I've heard of a form of cooling done by lasers known as "doppler cooling" because it is based on the Doppler effect. I think this is neat and would like to try to make a laser cooling device. I can't seem to figure out how though. I did some google research and all I get is cooling options for lasers rather than cooling options from lasers. What wavelength would you need to do this? Is there a particular way to do this rather than just shining a laser continuously at an object needing cooling. Would this work through a translucent object? I appreciate any help or guidance you could offer.

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Not practical lasers introduce energy into a system, you are talking about taking energy out of a system or neutralizing the atonic vibration.

There are frequencies that can be detrimental to a subject, to find them you send a full spectrum of noise at the subject and the detrimental frequency is the one that doesn't return. It is called harmonic vibration and it has been known to destroy superstructures.

You are talking of a frequency that will neutralize the atomic vibration of an element, the opposite of a microwave oven and water. A microwave doesn't heat up the meat, it heats up the water in the meat. What you want is a frequency that will neutralize the atomic vibration of water or some other element.

Dr. Freeze's freeze ray doesn't exist yet, but that doesn't mean it won't in the future.

To build one you need to figure out the element you want to neutralize the atomic vibration of and find the vibration that cancels or slows the atomic vibration down.

Hi, Joseph, laser cooling only works on dilute gasses of very cold atoms (it's used, for example, in the final states of the process of making a Bose-Einstein condensate).

The idea is that the laser (usually multiple beams coming from different directions) is tuned slightly low from one of the atoms energy levels, such that an atom moving towards the beam sees (blue shifted) the actual resonant frequency. When it absorbs the photon, it picks up momentum opposite its direction of motion, thereby slowing down just a bit.

When the atom re-emits back down to the ground state, that momentum kick is random. With beams coming from multiple directions, the overall process can result in the cloud being net cooled.

This should get you started:


keep in mind that you can't cool just anything:


(read under 'atomic structure' heading)

Lasers are powerful and their light causes a lot of heat.
I might be wrong but I think if what you want is actually possible, than certainly not on a hobby level.

Doppler laser cooling.

Take two lasers aim them at each other and turn them on.

Measure he redshift where the photons meet.

You could do that at home.

But I think the OP wants a freeze ray the opposite of a microwave oven.

Not practical yet.

mykiscool (author)  Downunder35m1 year ago

yes you are right, lasers introduce heat to an object if the movement of the light photons doesn't coincide with the atomic movement and causes the atoms to move faster, but if you hit the atom that's moving towards the light source with a photon that has an equal force in the opposite direction, the atom will no longer move according to Newton's law. Conventionally though this doesn't happen unless a laser is designed specifically for the purpose.

The creation of magneto-optical traps is a highly specialised field, and the objects in the trap have to be ultra-cold before you can even start. There are several methods, Wikipedia has an introduction.


TL:DR Its a very subtle process you are unlikely to be able to copy.