SENSING DEVICE AND METHOD FOR MEASURING EMISSION TIME DELAY DURING IRRADIATION OF TARGETED SAMPLES UTILIZING VARIABLE PHASE TRACKING

摘要

An apparatus (10) for measuring emission time delay during irradiation of a sample (32). A mechanism (14) generates first and second digital input signals (16, 26) of known frequencies with a known phase relationship, and a device (20, 28) then converts the first and second digital input signals (16, 26) to analog sinusoidal signals. A radiation source (22) is modulated at a specific frequency and irradiates the sample (32) and generate a sample emission (34). A device (36) detects the sample emission (34) and produces a first output signal (38) having a phase shift relative to the phase of the first input signal (16), and a mechanism (48, 50) converts the first and second analog output signals (38, 46) to digital signals. A mixer (52) receives the output signals (38, 46) and compares the signal phase to produce a signal (54) indicative of the change in phase. A feedback arrangement (56, 58) alters the phase of the second input signal (26) based on the mixer signal (54) to place the first and second output signals (38, 46) in quadrature.