After the user sets up TIR illumination and establishes the desired sample Z position, TIRF Lock™ keeps the sample in the focal plane by measuring the displacement of the exiting TIRF beam and maintaining that position via software feedback. The TIRF Lock™ system includes a quadrant photo-diode (QPD) head, a TIRF Lock™ controller, and a LabVIEW based VI. The TIRF Lock™ system is compatible with Mad City Labs RM21™ microscopes, the MicroMirror TIRF system, and the TIRF Module.
As shown in the diagram above on the left, a small change in Z position of the sample due to differential thermal expansion in the microscope will result in a small change in position of the exit beam on the detector. The software uses that change in position to calculate an opposing change in the nanopositioner Z position, as shown in the schematic above on the right.
Technical Specifications
Detector Wavelength Range
400nm-100nm
Detector Peak Responsivity
0.4A/W @635nm
0.67A/W @900nm
Recommended Incident Beam Size
300 µm to 1.5mmm
Sensor Size
2.4mm x 2.4mm
Clear aperture diameter
0.5 inches (1.25mm)
Aperture thread
SM05 (#0.535-40)
Detector head mounting thread
8-32 or M4
Mounting post holder thread
1/4-20 or M6 (magnetic base and clamping fork provided)