Fluorescence Lifetime Timing Gate for Dead-Time-Free Waveforms
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Solution Overview
Problem
Existing time measurement systems, such as TDC and TAC circuits, experience dead times during which they cannot measure time, leading to incomplete acquisition of time waveforms for phenomena like fluorescence, which affects the accuracy of synthesized time waveforms.
Innovation Solution
A time measurement apparatus with a gate unit that sets a gate dead time as an integral multiple of the phenomenon's repetition period, longer than the instrument's dead time, ensuring continuous time waveform acquisition by switching states and using a time-amplitude converter for high resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dead time is set in the time measurement instrument after each measurement, then the instrument can reset and prepare for the next measurement, but the time waveform cannot be acquired during the dead time, leading to incomplete data
Solution Approach 1:
The gate unit is configured to periodically switch between the first state (transmitting detection signals) and the second state (blocking detection signals) with a periodic time equal to an integral multiple of the repetition period of the phenomenon. This periodic gating allows the measurement instrument to operate in cycles, acquiring data during the first state and resetting during the second state, thereby eliminating dead time losses while maintaining measurement completeness
Solution Approach 2:
The gate unit is set to the first state before each measurement cycle begins, allowing detection signals to be transmitted to the measurement instrument in advance. This preliminary opening of the gate ensures that no measurement opportunity is lost at the beginning of each cycle, and the gate is closed in advance before the measurement instrument enters its dead time period
2Measurement precision
If the gate dead time is set to an integral multiple of the repetition period, then continuous waveform acquisition is achieved, but the gate unit must be precisely synchronized with the phenomenon repetition
Solution Approach 1:
The gate dead time parameter is set to an integral multiple of the repetition period of the phenomenon (e.g., 1×, 2×, or more). By changing the gate dead time parameter to match the phenomenon's temporal characteristics, the system achieves continuous waveform acquisition where the measurement windows of successive cycles align perfectly, eliminating gaps in the time waveform
3Reliability
If the gate dead time is longer than the instrument dead time, then the instrument dead time is completely covered, but the gate remains closed longer than necessary for instrument recovery
Solution Approach 1:
The gate unit operates in periodic cycles where it alternates between the first state (transmitting signals) and the second state (blocking signals). The periodic time of this switching is set to an integral multiple of the phenomenon repetition period, ensuring that the gate dead time completely covers the instrument dead time while maintaining measurement efficiency through synchronized periodic operation
Data Source
AI summary
A time measurement apparatus 10 includes a TAC circuit 12, a measurement gate 11, a control unit 14 for setting a gate dead time, which is a time during which the measurement gate 11 is set to be in the second state, in the measurement gate 11, and the control unit 14 for deriving and outputting time information related to the detection signal based on a measurement signal output from the TAC circuit 12, and the control unit 14 functioning as a setting unit sets a time, which is an integral multiple of a repetition period of fluorescence detected by the detector 4 and is longer than a dead time of the TAC circuit 12 itself, in the measurement gate 11 as a gate dead time.