Lesson 1: Fluorescence Filters

Modern flow cytometers can simultaneously monitor fluorescent signals in three or more areas of the spectrum. This ability is due to the use of fluorescence barrier filters which permit only selected wavelengths of energy to reach the photomultiplier tube (PMT) detectors. There are three kinds of barrier filters: 1) short pass, 2) long pass and 3) band pass. These names indicate which wavelengths may pass through each kind of filter. Short and long pass filters are usually glass plates containing or coated with materials which block selected wavelengths of energy. However, band pass filters, also referred to as cavity filters, are laminates of materials that will trap all wavelengths of energy except those wavelengths which have the same dimension as the space between the laminates.

A fourth kind of filter used in flow cytometers is the dichroic mirror which is coated with materials which will reflect selected (short or long) wavelengths of energy while permitting those wavelengths not selected to pass through the mirror. These mirrors are essential in directing specific wavelengths of the spectrum to specific PMT detectors in order to make simultaneous determinations of fluorescent signals in the flow cytometer.

 

 

Quiz 1-- Fluorescence Filters

Indicate the answer by selecting the appropriate button.

  1. Which wavelength will pass through a 550 nm long pass filter?
    None 470nm325nm 675nm All

  2. Which wavelength will be reflected by a 600nm short pass dichroic mirror?
    None 545nm710nm435nmAll

  3. What wavelength will pass through a combination of 545nm long pass dichroic mirror and 450/15 band pass filter?
    None 460nm 510nm 710nm All

  4. Fluorescence signals are always reduced if there are fingerprints or dirt on the fluorescence filters.
    True False

  5. Which wavelength will reach the PMT if a 500 nm short pass filter is place in front of a 488nm Argon laser and the energy from the excited sample labeled with FITC is reflected off of a 550nm long pass dichroic mirror, then passed through a 530/10 bandpass filter placed in front of the PMT?
    None 490nm 530nm 565nm All

Thank you for taking the time to answer the questions from this lesson. When you submit the answers, your score will be immediately posted below and recorded in the student database. Each question is worth one (1) point and when you reach a total of 80 points from cummulative quiz scores, you will receive a certificate of achievement and a discount coupon for FCSC products.

Quiz 1 Score:

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Revised: January 17, 1998.