Graham Lochead19/07/10

Lens setup for Rydbergspatial distribution

Graham Lochead19/07/10

Outline

• Spatial distribution experiment

• Translation stage

• Lens design

Graham Lochead19/07/10

Rydberg cloud distribution

5s2 1S0

5s5p 1P1

5sns 1S0

V

Lowdensity

Highdensity

Rydberg blockade should alter density profile

Graham Lochead19/07/10

Ground state distribution

• Measure ground state distribution from MOT floursecence

• Rydberg state scatters too few photons

Graham Lochead19/07/10

Autoionization

• Allows independent Rydberg excitation and investigation

• Ion detection is very sensitive

5s2 5s5p 5sns(d) 5pns(d) 5s1/2+

Graham Lochead19/07/10

Experiment plan

Need to scan across MOT

Graham Lochead19/07/10

Lens setup

Element Focal length

1 -30

2 -30

3 75

4 250

5 Viewport

• Spot size ≤ 10μm• Lenses outside chamber• Limit decentration/tilt error• Vibrationally insensitive

Constraints

Graham Lochead19/07/10

Translation stage

• 25mm travel

• Micron accuracy stepper motor

Newport miniature linear translation stage MFA-PP

Michelson interferometer

Graham Lochead19/07/10

LabVIEW knife-edge program

• Test translation stage LabVIEW drivers

• Need to check waist size and focal position

Stage steps → averages photodiode signal → Extracts std. dev.

Fits data using error function 2 % error on waist measurement

Graham Lochead19/07/10

Chromatic focal position shift

Alignment extremely challenging on autoionization transition- use 461 fluorescence

Chromatic shift important

Gaussian propagation fit

408 Rayleigh range ≈ size of MOT

Graham Lochead19/07/10

Viewport aberrations

Large increase in waist size

Focal position shift is achromatic

Large increase in aberrations

Not caused by tilt

Graham Lochead19/07/10

Outlook

• Lens system fully calibrated

• Translation stage calibrated

To do:

• Translation stage control in main Labview sequence

• Rebuild optical setup

• EIT lock