Laser sources are valued for the large amount of power they deliver. However, one of their characteristics is that the beams they produce have small divergences. This can be a limitation for those who require a powerful illumination over a wide angle. To address this issue, we have developed the NA converter, that modifies the geometry of an input fiber guided light beam. Both the numerical aperture and the beam diameter are affected : their product is a constant, so called Lagrange invariant.

The typical application in optogenetics is when the laser source is coupled to an NA 0.22 fiber-optic while the fiber-optic cannula of interest is made of a fiber-optic with NA 0.48. In this case, a magnification of x2.2 is well suited. In this example, with NA converter, the light going out of the output fibre will get twice of the input NA, i.e. 0.48 and fullfil the optical fibre NA.

NA converter is based on same design as the Connectorized U-bracket, then can also accept filter insert with attenuating or spectral filters. As a matter of fact, any filter can be fitted to our standard filter holder and its code can be engraved on its body. In this way you can build your set using off the shelf and custom filters.
The narrow band filters can be useful for filtering the fluorescence excitation spectrum or for the fluorescence light.