400-Hz mechanical scanning optical delay line.

Area of Science:

• Optics
• Spectroscopy
• Femtochemistry

Background:

• Femtosecond time-resolved measurements require precise control over optical path lengths.
• Existing optical delay lines can suffer from mechanical vibrations and limited speed, hindering signal averaging.
• High-speed, low-vibration delay lines are crucial for advanced spectroscopic techniques.

Purpose of the Study:

• To develop a simple, high-speed, and nearly vibration-free optical delay line.
• To enable efficient femtosecond time-resolved signal-averaging measurements.
• To demonstrate a novel mechanism for generating tunable optical delays.

Main Methods:

• Utilized a mechanically scanned, dithering planar mirror within a modified grating-lens femtosecond pulse shaper.
• The mirror acts as a time-varying linear phase ramp in the spectral plane.
• Optical delay is achieved through angular deviation of the mirror, creating a linear phase ramp.

Main Results:

• Developed a simple, high-speed, low-vibration optical delay line.
• Demonstrated a 2-picosecond (ps) time window autocorrelator with a display updated at 400 Hz.
• Achieved high speed and low vibration due to minimal angular mirror changes for significant time delay.

Conclusions:

• The developed optical delay line is suitable for femtosecond time-resolved signal-averaging.
• The system's high speed and low vibration characteristics significantly enhance measurement capabilities.
• This technology offers a promising solution for advanced ultrafast spectroscopy.