Electro-optic sampling oscilloscope

摘要

An electro-optic sampling oscilloscope facilitates adjustment of signal-to-noise ratio caused by electrical, optical and temperature factors. The instrument includes: a light generation section for generation a reference laser beam; a crystal (7), exhibiting an electro-optic response behavior so as to receive said reference laser beam and to result in changing a refractive index in accordance with electrical field strength generated by target signal; a reflection mirror (8) formed on a rear surface of said crystal for reflecting said reference laser beam that has passed through said crystal; an optical circuit (13,16) for separating said reference laser beam reflected from said reflection mirror into a first signal light and a second signal light; a first photo-electric conversion section (18) for converting said first signal light into first electrical signals; a second photo-electric conversion section (19) for converting said second signal light into second electrical signals; a differential amplification section (23) for differentially amplifying said first electrical signals and said second electrical signals, and for outputting differentially amplified signals as detection signals of said target signal; and a gain adjustment section for varying gains to adjust a signal-to-noise ratio while said reference laser beam is not being radiated into said crystal, so as to match strength levels of said first electrical signals and said second electrical signals in association with feedback signals of said target signal.