Optical Filters FAQs

Here we have provided comprehensive lists of commonly asked questions regarding our Semrock optical filters and related applications. This information is designed to support your inquiries, but if you don’t find the answers you are looking for we encourage you to contact us for further assistance.

Please use the sort buttons in the left navigation to navigate between questions and answers that are specific to Optical Imaging Systems, Fluidics, Cameras, Microfluidics, our Webstore, and Engineering Partnership.


How do you clean optical filters?

Materials Required:

  • Latex or Nitrile gloves
  • Cleanroom wipes
  • Cleanroom swabs in various sizes
  • Deionized water
  • HPLC grade methanol
  • Cloth to dab swab on to remove excess liquid
  • Tweezers
  • Nitrogen Compressed Air Supply
  • Fluid dispenser fluid dispenser


  1. Blow dust off optical filter with compressed air prior to using swab and solvent to clean.
  2. With gloves on, lay out filters on a cleanroom wipe.
  3. Even with gloves on, only handle filters by the edges with tweezers or fingers for best results.

General Cleaning:

  1. Select cleanroom swab size.
  2. Depress the fluid dispenser to flow cleaning fluid into the top, and touch the swab to the methanol (do not place swab directly into the fluid container).
  3. Touch the swab to the cleanroom wipe to remove excess liquid.
  4. Depending upon part size, apply swab to filter using a circular motion for round parts or an S-shaped motion for rectangular parts across the filter surface. It’s important to keep contact with the filter throughout this process.
  5. Turn filter over and repeat.
  6. Do not use the same swab side on the second filter side.

Find our demo video, more details on how to clean stubborn debris off optical filters and the do's and don'ts of cleaning optical filters in this how-to guide.

If you have edge blackened optical filters, check out this FAQ.