In a previous paper we described details of the construction of stabilized 670-nm diode lasers for use in undergraduate physics laboratories. We report here a series of experiments that can be performed using the 670-nm diode laser, a homemade scanning Fabry-Perot cavity, a helium-neon laser, a simple photodiode, and a few pieces of electronics hardware. The experiments include: 1) an introduction to the scanning confocal Fabry-Perot cavity, and to its use as an optical spectrum analyzer; 2) laser frequency modulation and observation of FM sidebands using the optical spectrum analyzer; and 3) the Pound-Drever method for servo-locking a Fabry-Perot cavity to a laser. These experiments are relatively easy to set up and perform, yet they demonstrate a number of useful optical principles and experimental techniques. 670-nm semiconductor diode lasers for use in undergraduate teaching laboratories. These inexpensive visible lasers emit tunable coherent light which can be used to perform a number of interesting and fundamental physics experiments. The lasers provide the foundation for a new 9-week (one quarter) senior physics lab course at Caltech, which consists of a series of experiments in optical and atomic physics. An attractive feature of the Caltech course is that it is track based; i.e. students all follow the same track in parallel. The course begins with simpler experiments to build up experience with the equipment and the physics; students then move on to more complex experiments as the course progresses. The equipment needed for these experiments is sufficiently inexpensive that several set-ups can operate simultaneously, which is necessary for a track-based course. 3 We describe here a series of three experiments involving lasers and Fabry-Perot cavities. The first (and simplest) experiment consists of aligning two spherical mirrors to form a confocal cavity, and using the cavity as an optical spectrum analyzer. This familiarizes the students with basic Fabry-Perot cavity concepts and gives them experience aligning an optical cavity. In the second experiment, the students use their optical spectrum analyzer to observe FM sidebands on a diode laser beam. The sidebands are produced by radio-frequency (RF) modulation of the diode's injection current. The shape of the FM sidebands is readily calculated, and students have the opportunity to compare their calculated spectra with observed spectra. In the third experiment, the students use the Pound-Drever method to lock a Fabry-Perot resonance frequency to the diode laser's frequency. FM sidebands are added to the optical carrier, and an optical/RF circuit produces an electronic error signal which is related to the difference between the laser frequency and the resonance frequency of the nearest longitudinal