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Doppler cooling is done in F=(4-5)transition state & in 10 MHz frequency shift.

In block diagram, from master laser(DL-100) the laser beam in the F=(4-5) transition

state first passes through the /2 wave plate (which is used to partially rotate the beam orused to change the polarization) & then it pass through the APP( Anamorphic prism pair)

which is used for making the beam circular which is actually elliptical in nature, so that it

is used to compress the elliptical beam inside to make it circular.

Then it goes through the /2 wave plate & inputted to the beam splitter.in this beam

splitter, the beam is totally refracted & not transmitted.The refracted beam then goes to the AOM1 of 115MHZ. In the AOM, the output, which

is shifted by v+f, we use this frequency; where the output is a function of RF frequency

& f and angle is also changed by changing the RF frequency & amplitude.

Here we change this angle in such a manner that we get the maximum of the power as(70-80)% in our output.

Here v is the input laser frequency, so the AOM output beam after frequency shifting it,

becomes F=(4-5)TRANSITION STATE-115mhz.

The input RF waves for AOM are supplied by direct digital synthesizer(DDS) whichgenerate RF wave.

RF wave is in the range of (65-95)MHz.The DDS & computer, controls the RF power& frequency. Then it is defoccussed by the

laser and becomes the beam parallel. One of the parallel beam passes through theCs cell

as a probe beam & inputted to the photo detector & another of the parallel beam also

paases through the Cs cell with the same frequency as a pump beam but withouthamperingthe 1st probe beam.

The second probe is also inputted to the photo detecto. In photo detector output we seethe frequency dip for (4-4) transition and (4-5) transition etc.Stablisation to 4 to(4-5) transition is done here.

So when we scan frequency b/w 4-4 & 4-5 transition it selects the midpoint 125MHz

then frequency shift occurs [F=(4-5)+115MHz-125MHz].So it becomes F= (4-5)-10MHz frequency shift.

This frequency is now usable for Doppler Cooling. All this is done in servo & it is then

fed back to the master laser.

Then this F= (4-5)-10MHz is totally transmitted through the PBS (Prism BeamSplitter)& then after passing through the /2 wave plate it just passes through the AOM2

& after reflecting the mirror it again passes through the AOM 2 & reflecting , the mirror

again passes through the AOM2.

So double shifting is done here i.e., frequency is now shifted to the F= (4-5)-140-10 that

means F= (4-5)-150MHz frequency shift is done here.

Then it is totally reflected it passes through 2 lasers which first focus and then defocus

the beam.

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This is done because b/w these lasers, shutter is actually used. Then it is amplified by the

tapered amplifier giving about 500nm light at the output of the amplifier as it becomes

small enough after this.

Then again we use the beam splitter. Some of the beam is vertically polarized and some

are horizontally polarized.The beam which is vertically polarized is then splitted into 2.

One of this passes through the AOM4 & after double shifting ,the frequency becomes

F= (4-5)-150+140 which is equal to the F=(4-5)-10MHz & then it is totally transmittedthrough the beam splitter and after passing through the /2& /4 wave plate it is inputted

to the optical fibre.

Another vertical polarisoing beam passes through the AOM5 & in the same manner it isdouble shifted & F=(4-5)-10MHz beam is inputted to the optical fibre.

AOM4 &AOM 5 are used for counter propagating verticals beams for launching atoms.

The