title: A high spatio-temporal resolution optical pyrometer at the ORION laser facility.
abstract: A streaked pyrometer has been designed to measure the temperature of ≈100 μm diameter heated targets in the warm dense matter region. The diagnostic has picosecond time resolution. Spatial resolution is limited by the streak camera to 4 μm in one dimension; the imaging system has superior resolution of 1 μm. High light collection efficiency means that the diagnostic can transmit a measurable quantity of thermal emission at temperatures as low as 1 eV to the detector. This is achieved through the use of an f/1.4 objective, and a minimum number of reflecting and refracting surfaces to relay the image over 8 m with no vignetting over a 0.4 mm field of view with 12.5× magnification. All the system optics are highly corrected, to allow imaging with minimal aberrations over a broad spectral range. The detector is a highly sensitive Axis Photonique streak camera with a P820PSU streak tube. For the first time, two of these cameras have been absolutely calibrated at 1 ns and 2 ns sweep speeds under full operational conditions and over 8 spectral bands between 425 nm and 650 nm using a high-stability picosecond white light source. Over this range the cameras had a response which varied between 47 ± 8 and 14 ± 4 photons/count. The calibration of the optical imaging system makes absolute temperature measurements possible. Color temperature measurements are also possible due to the wide spectral range over which the system is calibrated; two different spectral bands can be imaged onto different parts of the photocathode of the same streak camera.
authors.affiliation: AWE Aldermaston, Berkshire, RG7 4PR, United Kingdom.
authors.forename: Emma
authors.initials: E
authors.lastname: Floyd
authors.affiliation: AWE Aldermaston, Berkshire, RG7 4PR, United Kingdom.
authors.forename: Edward T
authors.initials: ET
authors.lastname: Gumbrell
authors.affiliation: AWE Aldermaston, Berkshire, RG7 4PR, United Kingdom.
authors.forename: Jim
authors.initials: J
authors.lastname: Fyrth
authors.affiliation: AWE Aldermaston, Berkshire, RG7 4PR, United Kingdom.
authors.forename: James D
authors.initials: JD
authors.lastname: Luis
authors.affiliation: AWE Aldermaston, Berkshire, RG7 4PR, United Kingdom.
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Skidmore
authors.affiliation: Imperial College London, Prince Consort Rd, SW7 2BB, United Kingdom.
authors.forename: Siddharth
authors.initials: S
authors.lastname: Patankar
authors.affiliation: Imperial College London, Prince Consort Rd, SW7 2BB, United Kingdom.
authors.forename: Samuel
authors.initials: S
authors.lastname: Giltrap
authors.affiliation: Imperial College London, Prince Consort Rd, SW7 2BB, United Kingdom.
authors.forename: Roland
authors.initials: R
authors.lastname: Smith