13,14) In these experiments, Doppler-free isotope lines of Yb were observed using saturation absorption spectroscopy. Absorption as low as 10-6 could be measured, and deposition-rate control with an accuracy better than 1% at a rate of 3.5 Å/s was demonstrated, which corresponds to a deposition-rate resolution of 0.03 Å/s. For example, a diode laser was stabilized to this transition using an Yb hollow-cathode lamp (HCL), which provides high number densities of atoms by using an electrical discharge. Light source, Hollow cathode lamp (HCL), Deuterium Arc lamp (D2) Modulation, Square wave pulse Modulation frequency. An electro-optic technique is described which allows a hollow cathode lamp to be modulated at microwave frequencies. is used to generate saw tooth signal and square pulse for modulation of the laser diode. The second derivative was used for deposition-rate monitoring and control of the process because it is proportional to the peak absorption. Experimental exercise 2: Spectroscopy of hollow cathode lamps. Mixing the detector output with the RF signal driving the electro-optic phase modulator resulted in a signal proportional to the first derivative of the absorption profile.
Single-mode optical fiber delivered the beam to the vacuum deposition chamber where it was focused onto a wideband photodetector. Cathode hole is 3 mm in diameter and 15 mm long. The lamp is a sealed glass tube filled with Ne (p3.5 Torr) containing a Mn cylindrical hollow cathode open at one end and a ring shaped anode. The laser beam was passed through an electro-optic phase modulator driven by a radio-frequency source, and its frequency was monitored with a hollow-cathode lamp as reference. We use a Hilger and Watts commercial hollow cathode lamp which is normally applied as a spectral source. We present the experimental study of modulation transfer spectroscopy of ytterbium atoms in a hollow cathode lamp. A high voltage is applied across the anode and cathode, resulting in an. citation needed Inside the sealed lamp, filled with argon or neon gas at low pressure, is a cylindrical metal cathode containing the element of interest and an anode. Based on frequency-modulation (FM) atomic-absorption spectroscopy, the scheme uses an external-cavity, 670-nm diode laser (New Focus, Santa Clara, CA). Hollow cathode lamps (HCL) are the most common radiation source in LS AAS. Researchers at Stanford University (Stanford, CA) and Focused Research (Santa Clara, CA) have developed an atomic-spectroscopy-based monitoring system for physical-vapor-deposition process control of yttrium. Atomic spectroscopy can monitor and control physical vapor deposition process
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