Photorefractive optical amplification, while useful, is a slow process. Under some circumstances, however, it amplifies
optical signals effectively even when one is modulated at a relatively high frequency. We determine the reasons for this
capability (what we have called the "Fast Photorefractive Effect") and analyze its enhanced bandwidth, improvements
over standard photorefractivity, and limitations.
Automatic target recognition (ATR) can be accomplished by many methods, including recognition of vibrometric
signatures. In many cases, ATR is enhanced by photorefractive amplification, a two-wave mixing effect in which two
input beams form a dynamic holographic grating. One of the two beams (the pump) diffracts from that grating into the
other (the signal), assuming the characteristics of the signal. When the pump is much stronger than the signal, the
diffracted pump becomes a highly amplified signal beam. Traditionally, however, the frequency at which this
amplification can be applied is limited to <1/2πτ0, where τ0 is the decay time of the grating in the absence of a pump or
signal. We demonstrate that the amplification has no such limit in the case of vibrometry, which measures
frequency-modulated, rather than amplitude-modulated, signals. This is shown by constant photorefractive amplification
at frequencies up to >700 kHz in Cu:KNSBN, which has τ0 >100 ms (corresponding to a maximum amplification
frequency of 1.6 Hz).
True 3D displays, whether generated by volume holography, merged stereopsis (requiring glasses), or autostereoscopic methods (stereopsis without the need for special glasses), are useful in a great number of applications, ranging from training through product visualization to computer gaming. Holography provides an excellent 3D image but cannot yet be produced in real time, merged stereopsis results in accommodation-convergence conflict (where distance cues generated by the 3D appearance of the image conflict with those obtained from the angular position of the eyes) and lacks parallax cues, and autostereoscopy produces a 3D image visible only from a small region of space. Physical Optics Corporation is developing the next step in real-time 3D displays, the automultiscopic system, which eliminates accommodation-convergence conflict, produces 3D imagery from any position around the display, and includes true image parallax. Theory of automultiscopic display systems is presented, together with results from our prototype display, which produces 3D video imagery with full parallax cues from any viewing direction.
An efficient room temperature all-solid-state laser system continuously tunable in the 0.2 - 10 micrometers spectral range has been developed. It is based on the alexandrite laser pumped LiF:F2+** color center laser system. The alexandrite - LiF:F2+** color center laser combination system has been shown to be a suitable drive source for a number of efficient nonlinear processes, including harmonic, sum-frequency and difference-frequency generation.
Highly efficient diffractive grating based on doped photorefractive crystal Bi12TiO20 have been applied for measurement of displacement after mechanic and temperature loading without application of external electric field. The diffraction efficiency of the doped crystal is discovered in non-optimized optical set up 100 times as much as that of the undoped crystals. Practically unlimited number of grating cycles of write, erase and read have been performed without optical damage and external electric or temperature fields. High adaptivity of this grating to external influence fields allows creation of a new optical development of small size diffractive dynamic elements -- DDE in contemporary optical engineering.
Conference Committee Involvement (7)
Practical Holography XXVII: Materials and Applications
3 February 2013 | San Francisco, California, United States
Practical Holography XXVI: Materials and Applications
22 January 2012 | San Francisco, California, United States
Practical Holography XXV: Materials and Applications
23 January 2011 | San Francisco, California, United States
Photonics in the Transportation Industry: Auto to Aerospace III
5 April 2010 | Orlando, Florida, United States
Practical Holography XXIV: Materials and Applications
25 January 2010 | San Francisco, California, United States
Practical Holography XXIII: Materials and Applications
25 January 2009 | San Jose, California, United States
Practical Holography XXII: Materials and Applications
20 January 2008 | San Jose, California, United States
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