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High contrast imaging can use pupil apodizers to suppress diffracted starlight from a bright source in order to observe its environs. Metallic half-tone dot transmissive apodizers were developed for the Gemini Planet Imager (GPI) and ESO SPHERE coronagraphs for use in the near-IR. Dot sizes on the scale of the wavelength of the light often result in unexpected variations in the optical transmission vs. superficial dot density relation. We measured 5 and 10 micron half-tone microdot screens' transmissions between 550 -1050 nm to prepare to fabricate apodizations that mitigate diffraction by segments gaps and spiders on future large space telescopes. We utilized slow test beams (f/40, f/80) to estimate the on-axis (far-field, or zero-order) transmission of test patches using a Fourier Transform Spectrograph on Beamline U10B at Brookhaven National Laboratory's National Synchrotron Light Source (BNL NSLS). We also modified our previous GPI IR characterization hardware and methods for this experiment. Our measurements show an internal consistency of 0.1% in transmission, a factor of 5 better than our near-IR GPI work on the NSLS U4IR beamline. The systematics of the set-up appeared to limit the absolute calibration for our f/40 data on the 50-patch, maximum Optical Density 3 (OD3), sample. Credible measurements of transmissions down to about 3% transmission were achieved for this sample. Future work on apodizers for obstructed and segmented primary mirror coronagraphs will require configurations that mimic the intended diffractive configurations closely in order to tune apodizer fabrication to any particular application, and measure chromatic effects in representative diffractive regimes. Further experimental refinements are needed to measure the densest test patches which possess transmissions less than a few percent. The new NSLS-II should provide much greater spectral stability of its synchrotron beam, which will improve measurement accuracy and reduce systematics.

The Gemini Planet Imager (GPI) is an extreme AO coronagraphic integral field unit YJHK spectrograph destined for first light on the 8m Gemini South telescope in 2011. GPI fields a 1500 channel AO system feeding an apodized pupil Lyot coronagraph, and a nIR non-common-path slow wavefront sensor. It targets detection and characterizion of relatively young (

High contrast imaging sometimes uses apodized masks in coronagraphs to suppress diffracted starlight from a bright source in order to observe its environs. Continuously graded opacity material and metallic half-tone dots are two possible apodizers fabrication techniques. In the latter approach if dot sizes are comparable to the wavelength of the light, surface plasmon effects can complicate the optical density (OD) vs. superficial dot density relation. OD can also be a complicated function of wavelength. We measured half-tone microdot screens' and continuous materials' transmissions. Our set-up replicated the f/ 64 optical configuration of the Gemini Planet Imager's Apodized Pupil Lyot Coronagraph pupil plane, where we plan to place our pupil plane masks. Our half-tone samples were fabricated with 2, 5, and 10 micron dot sizes, our continuous greyscale was High Energy Electron Beam Sensitive (HEBS) glass (Canyon Materials Inc.). We present optical density (OD) vs. wavelength curves for our half-tone and continuous greyscale samples 1.1 - 2.5 μm wavelength range. Direct measurements of the beam intensity in the far field using a Fourier Transform Infrared Spectrograph on Beamline U4IR at Brookhaven National Laboratory's National Synchrotron Light Source (NSLS) provided transmission spectra of test patches and apodizers. We report the on-axis IR transmission spectra through screens composed of metallic dots that are comparable in size with the wavelength of the light used, over a range of optical densities. We also measured departures from simple theory describing the array of satellite spots created by thin periodic grids in the pupil of the system. Such spots are used for photometry and astrometry in coronagraphic situations. Our results pertain to both ground and space based coronagraphs that use spatially variable attenuation, typically in focal plane or pupil plane masks.

Coherent synchrotron radiation from the NSLS VUV ring has been detected and partially characterized. The observations have been performed at the new far infrared beamline U12IR. The coherent radiation is peaked near a wavelength of 7mm and occurs in short duration bursts. The bursts occur only when the electron beam current (I) exceeds a threshold value (I{sub th}), which itself varies with ring operating conditions. Beyond threshold, the average intensity of the emission is found to increase as (I-I{sub th}). The coherent emission implies micro-bunching of the electron beam due to a longitudinal instability.

The first of several new infrared beamlines, built on a modified bending magnet port of the NSLS VUV ring, is now operational for mid-infrared microspectroscopy. The port simultaneously delivers 40 mrad by 40 mrad to two separate beamlines and spectrometer endstations designated U10A and U10B. The latter is equipped with a scanning infrared microspectrometer. The combination of this instrument and high brightness synchrotron radiation makes diffraction-limited microspectroscopy practical. This paper describes the beamline's performance and presents quantitative information on the diffraction-limited resolution.

The UV-storage ring Free Electron Laser (FEL) operating at Super-ACO is a tunable, coherent and intense (up to 300 mW) photon source in the near-UV range (300 - 350 nm). Besides, it has the unique feature to be synchronized in a one-to-one shot ratio with the Synchrotron Radiation (SR) at the high repetition rate of 8.32 MHz. This FEL + SR combination appears to be very powerful for the performance of pump- probe time-resolved and/or frequency-resolved experiments on the sub-ns and ns time-scales. In particular, there is a strong scientific case for the combination of the recently- commissioned SA5 Infra-Red Synchrotron Radiation beamline with the UV-FEL, for the performance of transient IR- absorption spectroscopy on FEL-excited samples with a Fourier-transform spectrometer coupled with a microscope allowing high spectral and spatial resolution. The principle and interest of the two-color combination altogether with the description of both the FEL and the SA5 IR beamline are presented. The first synchronization signal between the IR and the UV beams is shown. The correct spatial overlap between the UV (FEL) and the IR (SR) photon beams is demonstrated by monitoring via IR-spectro-microscopy the time evolution of a single mineral particulate (kaolinite) under UV-FEL irradiation.

A facility for performing time-resolved infrared spectroscopy has been developed at the NSLS, primarily at beamline U12IR. The pulsed IR light from the synchrotron is used to perform pump-probe spectroscopy. We present here a description of the facility and results for the relaxation of photoexcitations in both a semiconductor and superconductor.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Chemical mapping of proteins and lipids inside a single living cell and at a resolution of a few microns, has been performed using synchroton infrared microspectrometry. Modifications of the chemical distributions upon mitosis and necrosis has been investigated.

Electron synchrotron storage rings, such as the VUV ring at the National Synchrotron Light Source (NSLS), produce short pulses of infrared (IR) radiation suitable for investigating the time-dependent phenomena in a variety of interesting experimental systems. In contrast to other pulses sources of IR, the synchrotron produces a continuum spectral output over the entire IR (and beyond), though at power levels typically below those obtained from laser systems. The infrared synchrotron radiation (IRSR) source is therefore well-suited as a probe using standard FTIR spectroscopic techniques. Here the authors describe the pump-probe spectroscopy facility being established at the NSLS and demonstrate the technique by measuring the photocarrier decay in a semiconductor.

Infrared microspectroscopy combines microscopy and spectroscopy for the purpose of chemical microanalysis. Light microscopy provides a way to generate and record magnified images and visibly resolve microstructural detail. Infrared spectroscopy provides a means for analyzing the chemical makeup of materials. Combining light microscopy and infrared spectroscopy permits the correlation of microstructure with chemical composition. Inherently, the long wavelengths of infrared radiation limit the spatial resolution of the technique. However, synchrotron infrared radiation significantly improves both the spectral and spatial resolution of an infrared microspectrometer, such that data can be obtained with high signal-to-noise at the diffraction limit, which is 3 - 5 micrometers in the mid-infrared region.

The transient thermal photoresponse of YBCO thin epitaxial films is calculated for conditions comparable to those frequently used in actual photoresponse measurements. At low light fluences and low bias currents, the calculations are in accord with a linear bolometric response.At higher fluences and bias currents, the thermal response displays behaviors often attributedto a non-bolometric mechanism. This is particularly true for the response decay time, which can decrease as the temperature falls through T. Some comparisons with experiment are presented, and it is concluded that a careful analysis is required to distinguish non-bolometricfrom bolometric response, especially for conditions of high light fluence. 1. INTRODUCTION Since shortly after their discovery, the photoresponse of high-Tc cuprate superconducting films hasbeen actively studied. Interest has focused on the response of YBCO films to a short pulse of light. Suchmeasurements are expected to be affected by the relaxation processes for the photoexcitations, and theiranalysis could lead to a better understanding of the superconducting state. These studies are also motivatedby the prospect for developing a new class of high speed photodetectors.The photoexcitation process and relaxation mechanisms for a superconductor have been discussedby several authors1'2. The light energy is initially deposited into electronic excitations, and subsequentlyequilibrates among the various excitation modes of the system, i.e. it becomes thermalized. Details of thisrelaxation process depend on the coupling between various excitations of the system, such as the electron-phonon interaction. So, a detailed study of the relaxation following photoexcitation might be used toextract coupling constants important in the theory of superconductivity. Our understanding of therelaxation process is far from complete, and the relationship between a particular excitation and themeasured response is still being addressed. While Josephson-junction (i.e. phase) excitations are believedto be important in granular films, most discussions of the response in epitaxial films have focussed onbroken pair (i.e. amplitude) excitations2'3. One fact is well-established; the excitation energy which is notre-radiated appears as heat, characterized by a temperature rise AT. In the vicinity of T

We report studies of a thin high-Ta film operating as a fast bolometric detector of infrared radiation. The film has a response of several mV when exposed to a 1 W, 1 ns duration broadband infrared pulse. The decay after the pulse was about 4 ns. The temperature dependence of the response accurately tracked dR/dT. A thermal model, in which the film's temperature varies relative to the substrate, provides a good description of the response. We find no evidence for other (non-bolometric) response mechanisms for temperatures near or well below T.