Laser radiation may lead to permanent damage of the human eye when it is exposed to high power irradiation, especially when using magnifying optics such as binoculars, sights or periscopes. Into such an optical system we integrated a novel passive solid-state threshold-triggered Wideband Protection Filter (WPF) that blocks the transmission only if the power exceeds a certain threshold. At input powers below threshold, the filter has high transmission over the whole spectral band. However, when the input power exceeds the threshold power, transmission is decreased dramatically. We demonstrate the WPF integration within a typical optical system and the influence of system parameters on the protection capability of the filter.
We introduce into optical systems, susceptible to be interrupted or damaged from laser, novel passive solid-state
threshold-triggered Wideband Protection Filter (WPF) that blocks the transmission only if the power exceeds a certain
threshold. We present new protection capabilities of our latest filter composed of improved technology. The WPF can be
readily used for protection of detectors, cameras, or eye safety.
We present a passive, solid-state threshold-triggered Wideband Protection Filter (WPF) that blocks the transmission only
if the power exceeds a certain threshold. We demonstrate the protection ability of the WPF against laser threats including
protection behavior for single and series of pulses. The WPF can be readily used for protection of detectors, cameras, or
eye safety.
Imaging and detection systems are susceptible to detector saturation or permanent damage caused by powerful light sources or high power lasers. We propose and demonstrate a passive, solid-state threshold-triggered optical protection filter. At input power below threshold, the filter has high transmission over the whole spectral band. However, when the input power exceeds the threshold power, transmission is decreased dramatically. As opposed to fixed spectral filters, which permanently block only specific wavelengths, the wideband filter is clear at all wavelengths until it is hit by damaging light. When high incident optical power impinges on the wideband filter at a certain spot, this spot becomes permanently opaque. The wideband protection filter is fast enough to block nanosecond laser pulses.
We present a method to optically measure and image the membrane potential of neurons, using the nonlinear optical phenomenon of second harmonic generation (SHG) with a photopigment retinal as the chromophore [second harmonic retinal imaging of membrane potential (SHRIMP)]. We show that all-trans retinal, when adsorbed to the plasma membrane of living cells, can report on the local electric field via its change in SHG. Using a scanning mode-locked Ti-sapphire laser, we collect simultaneous two-photon excited fluorescence (TPEF) and SHG images of retinal-stained kidney cells and cultured pyramidal neurons. Patch clamp experiments on neurons stained with retinal show an increase of 25% in SHG intensity per 100-mV depolarization. Our data are the first demonstration of optical measurements of membrane potential of mammalian neurons with SHG. SHRIMP could have wide applicability in neuroscience and, by modifying rhodopsin, could in principle be subject for developing genetically engineered voltage sensors.
Confocal microscopy and optical tweezers were combined to develop a minimally invasive instrument capable of making hydrodynamic measurements more rapidly than is possible with other devices. This result leads to the possibility of making scanning images of the viscosity distribution of materials around bipolymer producing cells. An image of the viscosity distribution around a pullulan producing cell of Aureobasidium pullulans is shown as an example. We present results from experiments supporting a linearized model for the motion of a trapped bead in an oscillating harmonic potential. Fluid velocity measurements are tested by comparing to an independent video based measurement. We apply the technique to obtain a 2-D map of the flow past a microscopic wedge and compare to a theoretical solution for the stream lines assuming potential flow. Since the velocity is measured simultaneously with the trap relaxation time, it requires practically no calibration and is independent of the trap stiffness and the particle size.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.