Integrated Light Engines Simplify New Instruments
Another key trend in lasers for flow cytometry continues to be the increasing use of multi-wavelength light engines in benchtop clinical instruments. An example is the CellX from Coherent that integrates multiple OBIS lasers (see figure 3). Here all the lasers, electronics and beam shaping and focusing optics are housed in a single module to streamline the development of multi-parameter instruments. These off-the-shelf, standard engines are currently supplied with the four wavelengths most commonly used in multi-parameter instruments: 405, 488, 561, and 637 nm. (Importantly, all the optics are already compatible with the new UV laser wavelengths, in anticipation of future market demand.) Instruments typically use these as a series of elliptical foci (see figure 3) – where the short axis maximises the instrument’s time resolution and the broad lateral axis minimises sensitivity to changes in cell positions as the cells traverse the interrogation points.
Figure 3. Integrated light engines include the lasers and optics required to produce up to four focused beams, with the focal distance, shape and location of each beam independently set by the instrument builder. The optics are optimized for both visible and UV wavelengths.
These light engines are designed to offer highly flexible output to support different instrument designs. Precise independent adjustment of each of the four beams enables the separation between the staggered beam spots (see figure 3) to be varied from zero (i.e., co-aligned) to ±250 µm. The x and y ellipse dimensions can also be independently adjusted for each wavelength. Thus, the shape, size and position of each of the four focused laser beams can be adjusted to exactly match the geometry of a specific instrument. In addition, each of the four lasers is independently addressable and controlled through a standard USB connection.
There are several advantages to this new type of module. First, by outsourcing the beam conditioning and laser integration, the instrument builder cuts development costs and shortens the time to market while also minimising performance risk. And second, this integration provides cost-reduction through consolidation of hardware and electronics – for instance by using a single laser controller board, common power and single I/O connector. Moreover, outsourcing the photonics technology allows the instrument builders to focus on fluorochrome chemistry and other key differentiators, such as novel data analysis and other features.
Flow cytometry is a dynamic field, and the demands of both research and clinical application continue to evolve. Laser manufacturers are supporting these changes with new solutions to meet the needs of the next generation of instruments that will support important future developments in personalised medicine and tailored immune cell therapies.