Thousands of cells per second are counted and then characterized in biotechnical and medical analytics with laser-based flow cytometry. This allows for the fast and secure detection of blood anomalies.
Simultaneous Multi-Wavelength Detection
Flow cytometry is extensively used in the diagnosis of health disorders, particularly blood cancers, but has a number of other applications in basic research, clinical trials and clinical practice. It depends on the detection of fluorescence signals that are 1000 times weaker than scattered light, which in turn is 1000 times weaker than the light that the sample is illuminated with. Alas, the task in flow cytometry is to identify a signal that is a million times weaker than the illumination light. This indeed describes the high requirements to filters and dichroic beamsplitters that are employed in flow cytometry. For an in depth description of flow cytometry one can refer to BD's exceptional Flow Cytometry Web-Based Training or Oregon State University’s equally valuable resource Flow Cytometry - How Does It Work?
Separating Absorption and Emission Spectra
Absorption and emission spectra of most fluorophores (fluorescent dyes) are closely placed and often even overlap. Excitation and emission filters will need to have extremely steep edges to effectively separate absorption and emission peaks from each other. High out-of-band rejection is vital for making the weak fluorescence signal detectable among the powerful illumination light. Well-designed dichroic beamsplitters have extensive reflection and transmission wavelength ranges with a sharp transition in between. They enable suppressing the excitation light by at least two orders of magnitude and permit contrast rich imaging of cells and various other specimens.
Decades of Experience with Fluorescence Filters
Delta Optical Thin Film was the first to propose the use of interference filters to Carl Zeiss and Leica in the late 1960s. The company started volume manufacturing of fluorescence filters in the early 1970s and was the first to use computer controlled deposition in the early 1990s. Using its own synthesis and deposition control software, the company is able to offer coatings made with plasma assisted e-beam evaporation technology along with a quality equal to that attainable by IBS and other similar technologies. With decades of experience, today the company is the biggest supplier of high performance fluorescence filter sets to the key manufactures of fluorescence microscopes in the market.
This information has been sourced, reviewed and adapted from materials provided by Delta Optical Thin Film A/S.
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