Most of these tips are based on advice from Stephen Holtz when Habiba and Stephen revamped Berg4, so a big thank you to Stephen!

General principles/tips#

  • When setting up a rack (and this isn’t specific to imaging), it is worth the extra time to consider ergonomics, placing equipment in convenient locations (ex: at eye level), and practicing good cable management. The rig is something you will likely be using daily so putting in the extra time in the beginning can save a lot of time in the future.
  • This might sound obvious, but try to have all equipments/DAQs on the same side of the rack so you can see everything and where all the connections are going. This will also allow you to have shorter cables.
  • It is useful to have the bottom portion of the side of the blackout box closest to the rack covered with a curtain that you can flexibly snake wires through. You can then velcro the curtain to the air table. To make sure the side curtain is completely blacked out, you can make the curtain extra long and use magnets to drape over the side of the air table.
  • If possible, have the imaging-related cables exit the box separately from the other cables (such as behavior cables). For example, on Berg4, all the imaging cables exist from the top of the box and all the behavior cables from the side of the box. This is helpful for cable management and it also decreases the likelihood that you will pull on an imaging cable when moving behavior cables around.
  • The air table is designed to reduce motion, but if you have anything coupled to the air table that isn’t on the air table, this can introduce motion. So to reduce motion, make sure nothing rigid is coupled to air table. This also means that you shouldn’t to make the cables going to/from the rack and air table too short.
  • It is really useful to set up your rack so that you have shelves right under power strips. This will allow you to place power blocks on the shelf since they shouldn’t be on the floor. This also helps with organization and preventing the cables from dangling precariously and potentially getting unplugged.
  • You can use 1ft power extension cables to connect power blocks to the power strips without having them take up extra room and block other power inlets on the power strip.
  • Make cables as short as possible. This is especially important for data cables such as the PMTs. But make sure the cables coming to/from the rack aren’t too short that they would pull on the air table and produce motion.
  • Separate the main bundles of power strip and data cables along different sides of the rack. Since it is usually easy to get extension cables for the power strips, consider bundling them along the further end of the rack (from the air table). You can then bundle any data cables on the opposite side of the rack (closer to the air tables so that the data cables don’t have to be too long)
  • BNC paththroughs (ThorLabs part BNCB2) are very nice for mounting the PMT cables to the rack so that they are held securely in place and to reduce the amount of cable that is precariously dangling.

Grounding#

  • It’s important that everything is grounded at one point.
  • All power sources should be grounded to the rack.
  • The Pockels Cell usually isn’t grounded to the rack because it needs to be close to optics for easy access during alignment.
  • Computer/standing desk power can be a big source of noise so make sure they are properly grounded. It’s also good to have a separate power strip for them. For berg4, we separated them to the power strip on top of berg4.
  • The white labeled power strips have extra noise protection. The computers and data acquisition things should go there (as well as other sensitive equipment).
  • Remember that a lot of de-noising is empirical, so you might want to try grounding/ungrounding a device to see if it actually improves noise or potentially makes the noise worse.

Power strips#

  • The power strips should have a screw in the back (usually coated in a greenish-yellow color) that you can use to ground the power strips to the rack. If your power strip doesn’t have this, you should get one that does.
  • Ground the power strip by attaching wire terminals to both ends of the thick green grounding wire. One end can go to the power strip and the other can be screwed into the rack.

PMTs#

  • To ground the PMTs, wrap some copper wire around the BNC adaptor portion of the PMT cable and attach the wire to the rack using a wire terminal (see the picture in the first section).
  • You can also shield the PMT cables using shielding mesh and ground the shielding mesh to the rack. Test to see whether grounding the shielding improves the noise because we found that it did not improve the noise on Berg4.

Other devices#

  • The other electronic devices used for imaging will usually have a grounding port in the back (usually for a banana plug connection) that you can use to ground the device to the rack if the manufacturer thought they might need to be grounded.
  • You can try grounding the air table to rack at the end of the grounding process. This may or may not help with the noise, but it’s also something you’ll have to check. You also want to make sure this doesn’t increase the noise on another rig on the shared air table.