A Two-Dimensional Lock-In Algorithm for Signal Analysis in Patterned Images

Goal: We extend a classic signal processing algorithm, the lock-in amplifier, to two dimensions to extract the signal in patterned images. Methods: The algorithm was evaluated using simulated image data and experimental microscopy images to determine the fluorescence signal of fluorescently labeled proteins adsorbed on surfaces patterned with chemical vapor deposition. Results: The algorithm was capable of retrieving the signal with a signal-to-noise ratio as low as -20 dB. Optimal parameters were determined for the pattern design. Conclusion: The lock-in algorithm is a powerful technique for 1/f noise removal. Significance: The methodology holds promise not only for the measurement of adsorption events on patterned surfaces but in all situations where a signal has to be extracted from a noisy background in two or more dimensions.