INSTRUMENTATION
The Fizeau Wavelength Meter from New Focus (Sunnyvale, CA) provides wavelength information of pulsed and CW sources with a resolution of 0.001 nm and an accuracy of 0.01 nm over a range of 0.4 to 1.0 µm. Light enters the intrument through a pinhole and is reflected off the front and rear surfaces of an uncoated optic, forming a fringe pattern similar to that found on the surface of an oil slick. A highly sensitive detector converts the fringes into pixels. Because each color of light produces a unique fringe pattern, a built-in computer can use the pixel information to calculate the wavelength. The instrument is reportedly easy to use: a simple configuration makes alignment intuitive while a servo loo¥adjusts the input intensity to provide wide dynamic range. The detector sensitivity permits wavelength measurements of low-input-power beams. Introduced at CLEO `95, the instrument has no moving parts, meaning recalibration or alignment is not necessary. According to New Focus, the complexity is "in the electronics, not the optics," thereby reducing the cost without sacrificing resolution or accuracy.