A spectrometer line trigger is a signal that instructs the spectrometer to acquire a single line of spectral data per trigger, enabling precise synchronization with external events or devices.

What is a Line Trigger?

A line trigger is used in spectrometers with line-scan detectors, where the acquired data are one-dimensional arrays, or "lines" of spectral information. When a line-trigger signal is received, the spectrometer captures one unit of data per trigger, allowing precise control over the timing of each acquisition . This is particularly useful in applications where measurements must be synchronized with external events, such as pulsed light sources, moving samples, or electrochemical experiments .

Line Trigger vs Frame Trigger

• Line Trigger: Captures a single line of data per trigger. Each trigger corresponds to one acquisition cycle.
• Frame Trigger: Groups multiple line-triggered acquisitions into a single frame. Frame triggers can be edge-type (trigger at the start of a frame) or level-type (trigger remains active for the duration of the frame), allowing the spectrometer to organize multiple lines into a coherent dataset .

External Triggering and Signal Requirements

Spectrometers often support external triggering via TTL (transistor-transistor logic) signals, typically 0 V (Low) and 5 V (High). The trigger can operate in different modes:

• Edge Mode: The spectrometer triggers on a sharp rising edge of the input voltage, capturing a single spectrum per edge .
• Level Mode: The spectrometer continuously acquires data while the trigger signal remains at a defined level, stopping when the signal changes . The pulse width of the trigger signal is important; it must meet the minimum duration required by the spectrometer (commonly 10–50 µs) to ensure proper detection .

Practical Applications

Line triggers are widely used in:

• Spectroelectrochemical experiments: Synchronizing optical spectra with potentiostat-controlled electrochemical events .
• Pulsed light measurements: Triggering spectrometers with optical pulses from lasers or solar simulators using devices like the AvaTrigger .
• Time-resolved spectroscopy: Capturing spectral data at precise intervals to study dynamic processes.

Summary

A spectrometer line trigger provides precise control over data acquisition, allowing each line of spectral data to be captured in sync with external events. Understanding the type of trigger signal, voltage levels, pulse width, and mode (edge or level) is essential for accurate and reproducible measurements. Line triggers are often combined with frame triggers or external devices to organize and synchronize complex datasets efficiently .