1. Optical Alignment Manual

2. Optical alignment between the Output of Libra and the OPA system

3. Libra 40fs OPA BEAM PATH CM6 C.M2 BS1 IR1 M1 C.M1 C.M3 M2 IR2 M3 IR3

4. 1. Use CM6 to align the beam at IR1 : Block the transmitted beam of BS1 and the beam entering to OPA to avoid damage of optical components.
2. Use M1 to center the beam at C.M1
3. Use C.M1 to center the beam at BS1: put TIR (target IRIS) in front of BS1
4. Use BS1 to align the beam at IR2
5. Use C.M3 to align the beam at IR3
6. Use C.M4 to align the beam at IR4
OPA
Libra
40fs M1
IR1
C.M2
C.M1
BS1 M2
C.M3
C.M4
IR3
IR4 M3 M4
CM6
IR2
General Rules
To align the beam on 3rd Optical Components, the 1st should be used (not the 2nd).
1st
2nd
3rd

5. Optical Alignment in OPA part

6. Image of OPA

7. Scheme of OPA

8. Put target Iris on this convex lens
Block this pump Beam before align the seed beam on BBO(I).
Let align the optical component of BBO(I) before aligning the pump beam for BBO(II)
BBO(I)
BBO(II)

9. Alignment of pump beam for BBO(I)
Alignment of pump beam for BBO(I)
Direction of seed
Dash arrows are incorrect directions of pump

10. Put the card (could be name card or paper) here to see the output of BBO(I)
Time delay of seed and pump beam on BBO can be justify by the Translation stage here.
If the time delay is correct, we will see four bright, clear spots. If incorrect, there will be only one (pump only) or few dimmed spots. Alignment of both Pump and Seed might need to be checked again and again.

11. The four spots will be in the horizontal line that intersects the center of this iris.
After adjust the diameter of the iris to allow only signal light pass through, this signal light will automatically locate at the center of this irise.
If the seed and the pump are well-aligned,

12. Put target Iris on this convex lens

13. How to center the seed beam on BBO(II)
Use these mirrors to center the seed beam on the iris and BBO(II).
We need thermal paper to detect the seed beam
Block pump beam of BBO(II)

14. How to check spatial and time overlap of seed and pump beams
Block both the seed and pump beams of BBO(II) : (For safty)
Put dichroic mirror(DMLP 900: 800nm HR, 1250nm HT) just behind the BBO(II) to reflect the visible to the wall as shown in the figure.
With long distance, the beams will be clearly separated.

15. How to check spatial and time overlap of seed and pump beams
Use these mirrors (making spatial overlap of seed and pump beams), the translation stage ( making time overlap of seed and pump beams) and the remote control (changing the pulse durations) to make the these visible light become one bright spot.
Remote control

16. How to measure the energy (signal+idler)LP
Detector
If the thermal paper is placed at this point and move it; only one spot will be shown. if not(=pump and seed beams are not parallel), the alignment of the seed beam must be check again.

17. When the pulse duration was changed, time overlap should be checked.
How to stabilize and optimize the output energy (signal and idler) of BBO(II)
What involve in stabilization and optimization:
Both Translation stages (time overlap)
The remote control (change pulse duration)
Beams (seed and pump) parallel
Use the oscilloscope to see the peak of the pulse.
Stability stays between the Shortest adjustable pulse duration and the Longest adjustable pulse duration. LP
Detector
When the pulse duration was changed, time overlap should be checked.