Image beam amplifier

After the preamplifier, the beam is expanded to 2 mm, collimated and imaged onto a 1 mm aperture, producing a flat-top intensity profile. A 3-element telescope relays the aperture plane to the amplifier with a collimated 0.5-mm diameter. The telescope contains a spatial filter pinhole. The nominal power levels are 3 mW into the preamp, 500 mW out of the preamp and 200 mW out of the aperture. A 6° angle of incidence bounce beam geometry is utilized in the amplifier cell. The "bounce" foofprinf overlaps with the 4 pump beam fibers, arranged in 2 time sefs of 13 kHz. The pump fibers have f 50-60% fransmission. The amplifier brings the power up to < 20 W at 26 kHz. 

Figure 2. Amplifying a beam containing an image. Using a photorefractive material, the energy from a poor-quality, uniform pump beam can be coupled into the high-quality, weak beam containing an image. The beam is amplified and the image is retained.

Without the need for complicated magnetic lenses and electron beams, the STM is far less complex than the electron microscope. The tiiiy tunneling current can be simply amplified through electronic circuitry similar to that which is used in other electronic equipment, such as a stereo. In addition, the sample preparation is usually less tedious. Many samples can be im ed in air with essentially no preparation. For more sensitive samples which react with air, imaging is done in vacuum. A requirement for the STM is that the samples be electrically conductir, such as a metal. 

Fig. 1.33. Setup used by Smalley and coworkers to inject cluster ions into an ICR cell. The cluster beam is steered and focused by deflection plates and two Einzel lenses. Before entering the ICR cell, the cluster ions are decelerated. The inset shows the principle of an ICR mass spectrometer. Ions are excited by an rf-pulse to propagate in circular orbits. The image currents induced in the electrode plates are amplified and analyzed through computer-based Fourier transformation. The magnetic field in this scheme is perpendicular to the drawing plane. The schemes have been adopted from [71,177,178]...

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