In this report the first part of the assembly of the OPO cavity. For the drawing refer to file "assiemepdopov3asm.pdf". The pictures have been uploaded on drive at the following link: https://drive.google.com/open?id=1bjSdCoMSOHeWpJarAu0ZhKGuFZZME19h

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Step 1: check peltier (21) hot/cold side. In order to check which side of the peltier is the hot or cold one, the peltier has been powered up and the sides have been checked manually to determine which is the hot and which is the cold one. For this particular type of peltier, the cold side is the one with text (XF29) while the hot one is blank. See picture 1 and 2. Since we need the peltier to heat our crystal up, the cold side has been mounted in contact with the OPO assembly baseplate (6) while the hot one will be mounted in contact with the copper lower L (8). In order to ensure a good thermal contact between the components, a sheet of 0.1mm indium has been placed in between the peltier and the copper L.

Step 2: mount the thermometers (24) on the copper lower L (8) with the retainer (22, 23). See picture 3 and 4. After mounting the thermometers, bend the wiring of the thermometers and ensure the wires go in the groove, see picture 5.

Step 3: apply indium on the copper lower L and on the macor upper L (9). See picture 6.

Step 4: place the PPKTP crystal (7) in position. See picture 7. The PPKTP crystal mounted is the one with part number 7-11159316418, see picture 8. The crystal has a black dot on one side. I suppose this indicates the HR side, so the crystal has been mounted accordingly, see picture 9.

Step 5: assemble the lower and upper L on the peltier element and close the assembly with the POM bridge (5), see picture 10. Before doing this step, make sure the two POM tipped set screw (27) have been completely relased. While mountin the POM bridge be very careful about the crystal positioning. During this part one issue has been found and solved, see "Problem 1" part.

Step 6: fix the crystal position acting on the POM tipped screws. See picture 11. On this step be very careful not to brake the crystal. Alternate acting on X and Y screws, starting from the Y one. If you see the macor L starts tilting up, while acting on X, act on Y to fix the tilt. The final position of the assembly is when the peltier, and both the lower and upper L touch the left side of the POM bridge.

Step 7: mount the crystal holder retiner (25). See picture 12.

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Problem 1: during the step 5 of the assembling procedure an issue has been found. The Hexagon Socket Low Head Cap Screws (26) was not a "Low head cap screw", therefore this screw was interacting in a bad way with the POM tipped screw for X alignment, and was preventing the complete relese of this screw, necessary to start step 5 (see picture 13). This problem has been solved substituting this screw with a different screw with lower head cap (see picture 14 and 15). This solution allowed the release of the POM tipped screw for X alignment without problems.

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List of picture:
01 - peltier cold side
02 - peltier hot side
03 - copper lower L, thermometers and retainer before assembling
04 - copper lower L, thermometers and retainer after assembling
05 - lower L with thermometers in place and termometers wires bended
06 - indium applied to the lower and upper L
07 - crystal on the lower L
08 - crystal part number
09 - black dot on the crystal side indicating the HR (??) side
10 - POM bridge assembled
11 - crystal positioning using the POM tipped screws
12 - part 1 of OPO assembly finished
13 - problem with compenetrating screws
14 - new screw compared to old one
15 - compenetrating screw problem solved