A filter cube for TIRF microscopy

At the show, Chroma Technology Corp. talked about their newest product, a TIRF filter cube. Using the removable metal filter cube with a microscope allows wavelength tuning and mitigates evanescent wave depth mismatch by allowing adjustment of the angle of the dichroic mirror and the three cube walls. The high-quality dichroic mirror itself is only two to three millimeters thick. Incident light reflected by the tilted excitation filter is not reflected back along the incident light path, which keeps light from re-entering the laser, avoiding a possible interference pattern in the laser cavity or possibly even laser damage. A tilted emission filter helps reduce reflections within the microscope cube that might come from incident laser light or from fluorescence. The cube’s high mechanical stability (thanks to its metal composition) ensures that once it is aligned for TIRF the optical elements are not disturbed by torque, vibrations, or other mechanical forces. In addition, the component angles of the cube can be tuned so that the incident light strikes the sample at the critical incidence angle, creating total internal reflection. The microscope cube can be used in various microscopes. Adjusting the angle of the dichroic mirror will allow the cube’s optical elements to be aligned with optical elements of the microscope that is used.