Optical Properties of “Liumogen”: A Phosphor for Wavelength Conversion

Kristianpoller, N.; Dutton, David

doi:10.1364/ao.3.000287

Cited by 42 publications

(19 citation statements)

References 8 publications

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“…In addition, thin films of the phosphor have been shown not to degrade the imaging response of the CCD at visible and near IR wavelengths. The emission peak of liumogen is at 520 nm with a strong secondary peak around 560 nm 4 as shown schematically in Fig. 1.…”

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confidence: 91%

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Coronene and liumogen as VUV sensitive coatings for Si CCD imagers: a comparison

et al. 1980

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Phosphor coatings have long been employed in the detection of UV radiation.' With the interest in the use of silicon charge coupled device (CCD) imagers as the detector for the space telescope and other space-borne astronomical missions, a UV sensitive phosphor is desired the emission spectrum of which usefully matches the spectral response of the CCD. Such a phosphor would provide an unparalleled opportunity to image in the UV, the visible, and near IR wavelengths with the same detector. A recent study has suggested that coronene and sodium salicylate (which emit at 500 and 420 nm, respectively) are the most promising candidate phosphors. 2The potential of a third organic phosphor, liumogen, is the subject of this Letter. The use of coronene with a rear illuminated CCD detector has been recently reported.3 The emission peak of coronene at 500 nm represents a reasonable overlap with the sensitive region of the CCD spectral response. In addition, thin films of the phosphor have been shown not to degrade the imaging response of the CCD at visible and near IR wavelengths. The emission peak of liumogen is at 520 nm with a strong secondary peak around 560 nm 4 as shown schematically in Fig. 1. This represents a better match to the spectral response of the silicon CCD than coronene, and a much better match than sodium salicylate. Consequently, it was felt that a comparison of the response of coronene and liumogen would be useful.United Detector Technology pin photodiodes model 1ODP were used to evaluate the UV response of liumogen and coronene. The pin devices were preselected for nearly equal quantum efficiency in the neighborhood of 500 nm. To simulate the eventual use of the phosphor, the window of the package was removed, and the diodes were coated with a thin layer (0.025 mg/cm 2 ) of either coronene or liumogen:1600-2000 A in the case of coronene and 3600 A in the case of liumogen. The phosphors were deposited using an evaporative technique.3 Figure 2 presents the results of spectral response measurements on several coated devices. In the figure, the quantum efficiency of the detector/coating is presented as a function of incident wavelength from 121.6 nm (Lyman-a) to 460 nm. The measurements from 122 to 280 nm were performed at the University of Wisconsin at Madison using a Jarrell-Ash model 205 monochromator with a gas discharge source. An EMI 543-P-09-00 calibrated photodiode was used to measure the incident energy. Measurements between 320and 460 nm were performed in our laboratory using a 1000-W Xe source, a Schoeffel model GN 250-1 grating monochromator, and a calibrated Tektronix model J6504 probe to measure incident flux. The quantum efficiency of the phosphor coated diode was determined from the relationwhere 7 diode is the quantum efficiency of the device under test, T 1ref is the quantum efficiency of the reference detector, diode and 1 ref are the signal currents of the test device and reference diode, respectively. All measurements were performed at room temperature.As may be noted from Fig. 2 the c...

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“…Indeed, since the absorption edge of liumogen is at -460 nm, this layer absorbs photons that could be more efficiently detected by the uncoated photodiode. 4 The second observation concerning liumogen is that, in general, this phosphor is less efficient than coronene in converting UV photons to useful signal. This is true, in some …”

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Coronene and liumogen as VUV sensitive coatings for Si CCD imagers: a comparison

et al. 1980

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“…Furthermore, Lumogen has been used on the imaging CCD systems of the Hubble Space telescope and the Cassini space probe [6]. However, problems encountered in the production of Lumogen Ò coated CCDs for the Cassini spacecraft as highlighted in a Jet Propulsion Laboratory Report [7] indicated an instability in the crystalline structure of the as-deposited Lumogen Ò film, was originally suggested much earlier in a study by Kristianpoller and Dutton [8] and has been the focus of our work in this area [9,10].…”

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confidence: 99%

Grazing incidence X-ray studies of ultra-thin Lumogen films

Keough¹,

Hanley²,

Wedding³

et al. 2007

Surface Science

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“…While Lumogen Yellow S0790 is not the only choice of wavelength up-shifting material that is available or could be employed to improve device QE in the UV region, previous studies by Kristianpoller and others have shown that Lumogen is superior to coronene and sodium salicylate dye materials as the latter have less-uniform spectral response in the UV region than Lumogen does (with Dutton [3] and Knapp [4]). For example, coronene has a local minimum in the spectral response curve at approximately 380nm and silicon CCDs experience a UV response cut-off at around 400nm [5], thus a coronene coated CCD exhibits a bandpass type behaviour where UV light in between those limits (ie from ~380-400nm) would be relatively undetected.…”

Section: Introductionmentioning

confidence: 99%

“…Notwithstanding the superior optical properties of Lumogen for UV detection applications, Kristianpoller and Dutton noticed that a clear and transparent evaporated film would turn cloudy after a few days or weeks of storage at room temperature, and attributed this change to partial crystallisation within the film [3]. They also reported that the luminescence efficiency of these films does not change despite a suggested phase transition.…”

Section: Introductionmentioning

confidence: 99%

Characterization of PVD Lumogen films for wavelength conversion applications

Deslandes

Wedding

Clarke

et al. 2005

Smart Structures, Devices, and Systems II

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Lumogen Yellow S0790 is a commercial azomethine based pigment and is used for enhancing CCD devices for detecting ultraviolet radiation. In this work we report on the crystal structure and morphology of the raw material, as-deposited and post-annealed films, as well as the influence these have on the subsequent optical properties. Our measurements of physical vapour deposited (PVD) Lumogen films indicate that commercial Lumogen powder is crystalline in its as-received state, with a melting point of 273.3°C and boiling point of 328.6°C. Furthermore, we have found that as-deposited films on room temperature substrates possess an inherent crystalline structure, which has not been reported previously, but also that the material's structure changes into a completely different crystalline form upon annealing for 90 hours at 80°C.

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Optical Properties of “Liumogen”: A Phosphor for Wavelength Conversion

Cited by 42 publications

References 8 publications

Coronene and liumogen as VUV sensitive coatings for Si CCD imagers: a comparison

Coronene and liumogen as VUV sensitive coatings for Si CCD imagers: a comparison

Grazing incidence X-ray studies of ultra-thin Lumogen films

Characterization of PVD Lumogen films for wavelength conversion applications

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