Increased efficiency for multicolor detection

Innovations in the optical system, pioneered by BD, efficiently maximize signal detection and greatly increase sensitivity and resolution for each color in a multicolor assay. Enhanced sensitivity and resolution mean that even dim populations can be readily identified and sorted.

The optics system allows optimizing multicolor assays and panel design for superior results. The design provides researchers a choice of laser excitation wavelength(s) that illuminate cells in the sample. Collection optics direct light scatter and fluorescence signals through spectral filters to detectors. Innovative designs for both the excitation and collection optics reduce excitation losses and dramatically improve collection efficiency, yielding better information from each sample..

Excitation optics

The excitation optics consist of multiple fiber-launched fixed-wavelength lasers, beam-shaping optics, and achromatic focusing lenses that produce beam spots that are spatially separated and concentrated (9 μm x 65 μm). The more concentrated the beam spot, the higher the signal produced as each fluorescent-labeled particle passes through the laser spot. Laser light is focused into the gel-coupled cuvette flow cell. Optical gel coupling to the fluorescence objective lens enables transmission of the greatest amount of emitted light from the interrogation point to the collection optics. Since the optical pathway and the sample core stream are fixed, alignment is constant from day to day and from experiment to experiment.

Sensitivity and resolution beyond compare.

Fixed alignment also ensures that there is no variability in experiment results introduced by manual optical adjustments.

FACSAria III - Optics parsley 1

Transmission pathways in an octagon

Collection optics

Fiber optics deliver emitted light from the gel-coupled cuvette to the detector arrays. The collection optics are set up in patented octagon pathways that maximize signal detection from each laser illuminated beam spot. This is accomplished by transmitting the highest wavelengths (which have the fewest photons of light) to the first photomultiplier tube (PMT), and reflecting lower wavelengths to the next PMT through a series of longpass dichroic mirrors.

This design is based on the principle that light reflection is more efficient than light transmission. Emitted light travels to each PMT via reflection and is transmitted through only two pieces of glass to reach each detector. Therefore, colors can be detected with minimum light loss.

Bandpass filters in front of each PMT allow spectral selection of the collected wavelengths. Importantly, this arrangement simplifies filter and mirror changes within the optical array and requires no further alignment, for maximum signal strength.

Precision optical design

The many innovations in the BD FACSAria Fusion’s optical system, such as the patented gel-coupled cuvette and octagon detection system, and the 9-μm x 65-μm beam spot, are designed to work together to maximize sensitivity and resolution. This precision design delivers a more efficient optical system enabling the use of lower powered lasers, which in turn reduces the total cost of instrument operation.