The generation of optical harmonics is discussed in this letter. The authors describe experiments in which second harmonic light (at 3472 Å) was produced by passing an intense beam of 6943 Å light through crystalline quartz. The second harmonic was observed in a quartz prism spectrometer, and the results were confirmed by the disappearance of the signal when quartz was replaced by glass. The results also showed the expected dependence on polarization and orientation, as summarized in Table I. The authors suggest that the second harmonic intensity could reach up to a fraction of a percent of the fundamental intensity. The experiments used a ruby laser producing 3 joules of 6943 Å light in a one-millisecond pulse. The light was focused inside a quartz sample, and the emergent beam was analyzed. The results indicate that the order of 10¹¹ second harmonic photons were generated per pulse. The authors also note that second harmonic generation could be observed in isotropic materials like glass if a strong bias field were applied. The work was supported by Trion Instruments, Inc. The results demonstrate the feasibility of using nonlinear materials such as quartz for the production of optical harmonics. The experiments confirm the production of second harmonic light and provide evidence for the nonlinear optical properties of quartz. The results are significant for the development of optical harmonic generation techniques.The generation of optical harmonics is discussed in this letter. The authors describe experiments in which second harmonic light (at 3472 Å) was produced by passing an intense beam of 6943 Å light through crystalline quartz. The second harmonic was observed in a quartz prism spectrometer, and the results were confirmed by the disappearance of the signal when quartz was replaced by glass. The results also showed the expected dependence on polarization and orientation, as summarized in Table I. The authors suggest that the second harmonic intensity could reach up to a fraction of a percent of the fundamental intensity. The experiments used a ruby laser producing 3 joules of 6943 Å light in a one-millisecond pulse. The light was focused inside a quartz sample, and the emergent beam was analyzed. The results indicate that the order of 10¹¹ second harmonic photons were generated per pulse. The authors also note that second harmonic generation could be observed in isotropic materials like glass if a strong bias field were applied. The work was supported by Trion Instruments, Inc. The results demonstrate the feasibility of using nonlinear materials such as quartz for the production of optical harmonics. The experiments confirm the production of second harmonic light and provide evidence for the nonlinear optical properties of quartz. The results are significant for the development of optical harmonic generation techniques.