User-friendly
Vogt needed a user-friendly optical-design and -analysis package to build these instruments. He found ZEMAX to be powerful and easy to learn. He said, "Its tolerancing features were particularly useful for final alignment tasks. I don't like to invest lots of time using products with overly lengthy manuals to read, or overly steep learning curves to climb. I got up to speed and became productive quickly with ZEMAX."
The spectrometers' use for planet search is described in a March 1998 article in Sky and Telescope, written by R. Paul Butler and Geoffrey Marcy (the latter was one of Vogt's first graduate students). The authors said that the detection of planets outside our solar system has been all but impossible because they are lost in the glare that surrounds a star's image.
To remedy this, the astronomers are using an indirect method of detection: They are employing the Doppler effect to detect tiny "stellar wobbles" that result from a gravitationally bound planet swinging its star around in a mirror image of its own orbit. This allows them to determine the existence of an unseen orbiting body. The size of the wobble indicates the planet's mass. The planet's orbital period is determined by the amount of time it takes for the star to complete one wobble.
The authors say that since 1995 eight extrasolar planets of sunlike stars have been positively detected.