Selection starts with the dye or probe
Fluorescence filter selection starts with the dye or probe your assay uses, not with a wavelength you have not confirmed. The documented dye and probe list for fluorescence filters is FAM, SYBR Green, Green, HEX, TET, Cy3, JOE, ROX, Cy3.5, Texas Red, Cy5, LC Red640, and Cy5.5, with others in the same documented list. If your assay uses a name on that list, selection can proceed against the documented excitation and emission examples. If your assay uses a name outside that list, selection cannot proceed by assumption: state that name in your inquiry and ask whether it is covered.
From dye or probe to excitation and emission
Each dye or probe has an excitation behaviour and an emission behaviour. The documented excitation and emission examples for fluorescence filters are Ex 470-30 / Em 525-20, Ex 523-20 / Em 564-20, Ex 543-20 / Em 584-20, Ex 571-20 / Em 612-20, and Ex 628-35 / Em 692-45, with cross blocking greater than 6. Those examples show the form in which excitation and emission values are given, and they let a buyer compare a requirement against a documented example. They do not cover every dye or probe, and they do not replace a confirmation in the inquiry. The selection step is therefore a matching step: match your dye or probe to the documented list, match your excitation and emission requirement to a documented example where one exists, and ask for confirmation where no example matches.
Blocking, slope, and set composition
After excitation and emission, the next selection factors are blocking and slope. Blocking is documented as OD greater than 6 at 200 to 900 nm, or at 200 to 1200 nm, with cross blocking OD greater than 6. Slope is documented as 50 percent to OD5 less than 10 nm. Those figures matter because fluorescence readings measure weak emission against strong excitation: stray excitation light must be kept out of the detector path, and the transition between the pass region and the blocked region must be steep enough to keep the two apart. Buyers who need a blocking or slope figure for a different wavelength range should state that range in the inquiry and ask for confirmation. Finally, decide whether you need single pieces or a cemented filter set. Multiple pieces can be cemented into a fluorescence filter set, which suits applications that need excitation, emission, and related elements working as one assembly. State the elements you need and the dye or probe each one serves.
Selection by application
Application shapes selection in two ways. First, the instrument family matters: biomedical fluorescence detection analysis systems and real-time fluorescence quantitative PCR instruments are the documented application families, and the PCR family covers molecular biology, food safety testing, and public health epidemic monitoring. Second, the assay matters: the dye or probe you use decides which excitation and emission example is relevant. The PCR fluorescence guide covers the application side, and the fluorescence filters page carries the full specification evidence. The dye selection note explains selection by dye and probe name in more detail.
Selection checklist
Please confirm the following items in your inquiry before ordering: the dye or probe name; the excitation and emission requirement; the blocking range you need; the size you need from the documented sizes or the size you require; whether you need single pieces or a cemented filter set; and the quantity basis and delivery basis for your order.