Particle contamination is analyzed for a reticle in the inner pod of a carrier with particular emphasis on the effect of
raising the cover of the inner pod before removing the reticle from the carrier at atmospheric pressure (not low pressure).
Two mechanisms for particle transport into the gap between the base plate and the reticle are considered: injection and
advection-diffusion. It is shown that injection is not an important mechanism but that advection-diffusion transport can
carry particles deeply into the gap, where they can deposit on the reticle surface. Closed-form expressions are presented
for the transmission probability that particles at the reticle edge are transported inward past the exclusion zone around
the reticle perimeter. The gas flow in the gap that occurs during cover-raising is found by numerical simulation, and the
closed-form expressions are applied to determine the probability of contamination for different cover-raising scenarios.
Optical measurement techniques are extremely useful in fluid mechanics because of their non- invasive nature. However, it is often difficult to separate measurement effects due to pressure, temperature and density in real flows. Using a variation of a Shack-Hartmann wavefront sensor, we have made wavefront measurements that have extremely large dynamic range coupled with excellent sensitivity at high temporal and spatial resolution. These wavefront variations can be directly related to density perturbations in the fluid. We have examined several classes of flow including volumetrically heated gas, grid turbulence and droplet evaporation.
The wavefront error across a laser aperture is often the limiting factor in laser resonator design and performance. For long-pulse, sidepumped lasers, such as some nuclear-reactor-pumped or flashlamp-pumped lasers, significant transverse index gradients can develop and couple to the laser resonator modes. To design a laser resonator for efficient power
extraction, a spatially and temporally resolved determination of the index variation is required. High-speed photography using a fastframing camera with a modification of the Hartmann technique is applied to measure the index field and the resulting wavefront error in the gain region of a pulsed,
nuclear-reactor-pumped laser. With moderate initial gas pressures, the index fields and the wavefront errors are found to have roughly parabolic shapes except near the side walls. These results are in reasonable agreement with the predictions of a gasdynamic model, which describes the gas motion induced by the spatial nonuniformity of the pumping.
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.