BD LSRFortessa X-20

Maximum Signal, Minimum Crosstalk

The patented collection optics of the BD LSRFortessa™ X-20 are arranged in polygon-shaped optical pathways. Their novel design efficiently maximizes signal detection and increases sensitivity and resolution. This enables researchers to identify cells with especially dim expression, or quantitate rare cell populations, by optimizing multicolor assays and panel design for best results.

Optics - Lab Image

Optics System

The optics system uses a novel laser design that illuminates cells in the sample, and collection optics that direct light scatter and fluorescence signals through spectral filters to the detectors. Innovative designs for both the excitation optics and collection optics in the BD LSRFortessa X-20 system minimize light loss and optimize collection efficiency for increased sensitivity and resolution.

Excitation Optics

The excitation optics consist of multiple fixed-wavelength lasers, beam-shaping optics, and individual pinholes which result in spatially separated beam spots.

A final lens focuses the laser light into the gel-coupled cuvette flow cell. Since the optical pathway and the sample core stream are fixed, alignment is constant from day to day and from experiment to experiment.

Collection Optics

Emitted light from the gel-coupled cuvette is delivered by fiber optics to the detector arrays. The polygonal optical pathways maximize signal detection from each laser-illuminated beam spot. Bandpass (BP) filters in front of each photomultiplier tube (PMT) collect selected fluorophore spectral wavelengths. This arrangement allows filter and mirror changes within the optical array to be made easily without additional alignment.

This design efficiently exploits the principle that light reflection is more efficient than light transmission for fluorescence signal detection. Emitted light travels to each PMT detector via reflection, and is transmitted through only two pieces of glass to reach the detector. Therefore, more colors and higher panel multiplexing can be achieved with minimum light loss.

Optimal resolution of cell populations
Optimal resolution of cell populations
The high sensitivity of the BD LSRFortessa™ X-20 allows for optimal resolution of lower expression antigens and rare cell subsets. In this example, regulatory T cells (Tregs), characterized by low levels of expression of CD127 and high levels of CD25, were easily identified. Note the resolution of different levels of expression of CD25 and CD127.