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SUMMARY Objectives: To correlate the radiant power (mW), radiant exitance (or tip irradiance in mW/cm2), emission spectrum (mW/cm2/nm), and beam irradiance profile of 12 light-curing units (LCUs) available in the Brazilian market with their market cost. Methods and Materials: Six LCUs that cost more than US$900 (Bluephase G4,VALO Grand, VALO Cordless, Radii Xpert, Elipar DeepCure-S, and Radii plus) and six low-cost LCUs costing less than US$500 (Radii Cal, Optilight Max, High Power LED 3M, Emitter D, Emitter C, and LED B) were examined. Radiant power (mW) and emission spectrum (mW/nm) were measured using an integrating sphere connected to a fiber-optic spectroradiometer. The internal tip diameter (mm) of each LCU was measured using a digital caliper and was used to calculate the average radiant exitance (mW/cm2). Irradiance profiles at the light tip were measured using a commercial laser beam profiler. The cost of each LCU in Brazil was correlated with internal tip diameter, radiant power, and tip irradiance. Results: None of the low-cost LCUs were broad spectrum multiple peak LCUs. There was no correlation between the cost of the LCUs and their averaged tip irradiance; however, there was a high positive correlation between the cost of the LCUs and the radiant power and tip diameter. The VALO Grand, Elipar DeepCure-S, VALO Cordless, and Bluephase G4 all emitted a higher radiant power. They also had a significantly greater tip diameter than other LCUs. For the LCUs with a nonuniform output, some areas of the light tip delivered less than 400 mW/cm2, while other areas delivered more than 2500 mW/cm2. Conclusions: In general, LCUs that had a higher cost (US$971–US$1800) delivered more power (mW) and had a greater tip diameter (mm), which covered more of a tooth. In general, the low-cost LCUs (US$224–US$470) emitted a lower radiant power and had a smaller tip diameter.

Light-emitting diodes (LEDs) based on perovskites show great potential in lighting and display applications. However, although perovskite films with high photoluminescence quantum efficiencies are commonly achieved, the efficiencies of perovskite LEDs are largely limited by the low light out-coupling efficiency. Here, we show that high-efficiency perovskite LEDs with a high external quantum efficiency of 20.2% and an ultrahigh radiant exitance up to 114.9 mW cm−2 can be achieved by employing the microcavity effect to enhance light extraction. The enhanced microcavity effect and light out-coupling efficiency are confirmed by the study of angle-dependent emission profiles. Our results show that both the optical and electrical properties of the device need to be optimized to achieve high-performance perovskite LEDs.

LED-based integrating sphere light sources (LED-ISLSs) in the size of typical microscope slides were developed to calibrate the radiance responsivity of optical imaging microscopes. Each LED-ISLS consists of a miniaturized integrating sphere with a diameter of 4 mm, an LED chip integrated on a printed circuit board, and a thin circular aperture with a diameter of 1 mm as the exit port. The non-uniformity of the radiant exitance of the LED-ISLSs was evaluated to be 0.8%. The normal radiance of the LED-ISLSs in the range of (5∼69) W m−2 sr−1 was measured with a standard uncertainty of 1.3% using two precision apertures and a standard silicon photodetector whose spectral responsivity is traceable to an absolute cryogenic radiometer. The LED-ISLSs were applied to calibrate the radiance responsivity of a home-built optical imaging microscope with a standard uncertainty of 2.6∼2.9%. The LED-ISLSs offer a practical way to calibrate the radiance responsivity of various optical imaging microscopes for results comparison and information exchange.

A mid-IR optical emission spectrometer (mid-IR OES) was designed and constructed to detect the absolute spectral radiant exitance of IR signatures. A 256-array PbSe detector was adopted to analyze the mid-IR emission spectrum from countermeasure flares. The spectral response of the optical emission spectrometer was obtained using a directly heated graphite blackbody. The absolute emissions of their IR signatures were inferred by applying spectral response to the spectrum intensity data. Also, we devised a post processing method for compensating diffraction order overlap in a mid- IR grating spectrometer using an array detector. We confirmed the validity of the compensation method by comparing the signal intensities acquired using the different methods.

Both surfaces of fine ceramics used for electric parts are covered with, for example, a resin, a ceramic alumina or a solder. An automatic optical method for detecting cracks originating at the side faces of ceramic parts, the surfaces of which are covered with the above-mentioned materials, has been developed and is reported in this work. A laser beam is diffused into the specimen by illumination onto the side faces through an objective lens. When the specimen has a crack near the laser spot, the diffused laser light is reflected by the crack and the amount of radiant exitance near the crack is increased. The image of the side face is enlarged by the objective lens and detected by a CCD camera. It is clarified experimentally that it is possible to recognize the region surrounded by a close-ended crack wider than 20μm and longer than 351im, or an open-ended crack longer than 50μm, by detecting signals higher than the average level with the CCD camera.

Photodynamic therapy (PDT) is an experimental therapy for the treatment of superficial cancer using laser light. In PDT a uniform light distribution is usually required for an optimal therapeutic effect. To irradiate part of the oral cavity uniformly for PDT, two prototype applicators were built, each for a different lower jaw. The applicators made use of the light transmitted through the wall of a cavity of diffusely reflecting material. The radiant exitance of the applicators was measured at 632.8 nm. For the radiant exitance of M of the two applicators, a uniformity ratio, UR = Mmax/Mmin < 2 was found, which was considered reasonable for clinical applications. Calculations predict that the UR can be improved by decreasing the thickness of the cavity wall

The relationship was derived for computer-controlled color CRT displays between spectral radiant exitance emitted and digital counts. The derivation was historical and could be traced to pioneering work in photographic sensitometry, vacuum tube physics, and broadcast television. By performing radiometric measurements relative to a display's maximum exitance, the model simplified to a two-stage model. The first stage was a nonlinear transformation relating normalized digital-to-analog converter values to device-dependent monitor tristimulus values using model parameters of gain, offset, and γ. The second stage was a linear transformation where the device-dependent monitor tristimulus values were transformed to device-independent CIE tristimulus values. By using the model, colorimetric characterization accuracy of better than 0.5 CIELAB color-difference units for 125 colors sampling the display color gamut was achieved by measuring the CIE tristimulus values of only eight colors. The model had equivalent performance to methods using extensive measurements and table lookup. © 1993 John Wiley & Sons, Inc.

The colorimetric characterization of computer-controlled CRT displays require radiometric measurements with high precision and accuracy in order to achieve acceptable colorimetric accuracy in defining stimuli generated with this type of imaging modality. Precision and accuracy requirements for photometers, colorimeters, and spectroradiometers were evaluated. When models are used to relate digital counts defining a stimulus and resulting spectral radiant exitance, displays are assumed to exhibit channel and spatial independence. A variety of tests and the results of evaluating four imaging systems are described. From these analyses, measurement accuracy is mainly limited by wavelength scale in the case of spectro-radiometers and filter fit in the case of colorimeters. Measurement precision is limited by the number of significant figures for fixed-range devices and signal-to-noise limitations for low-luminance stimuli. Display accuracy is limited by a lack of channel and spatial independence. Display precision is mainly limited by the electronic design of the display and the stability and load independence of the gun amplifiers. © 1993 John Wiley & Sons, Inc.

Raman spectroscopy is a powerful technique for materials analysis, and we are developing and analyzing a remote Raman system for use on a planetary lander or rover. We have acquired data at a distance of 10 m from a variety of geologic materials using different instrument designs. We have employed a pulsed laser with both an ungated detector and a gated detector. A gated detector can reduce long-lived fluorescence while still collecting all Raman signal. In order to design a flight instrument, we need to quantify how natural surfaces will respond to laser stimulus. We define remote Raman efficiency of natural surfaces as the ratio of radiant exitance leaving a natural surface to the irradiance of the incident laser. The radiant exitance of a natural surface is the product of the sample radiance, the projected solid angle, and the full-width-half-maximum of the Raman signal. We have determined the remote Raman efficiency for a variety of rocks and minerals. The best efficiencies are achieved for large, clear, single crystals that produce the most radiant exitance, while darker fine-grained mineral mixtures produce lower efficiencies. By implementing a pulsed laser, gated detector system we have improved the signal detection and have generally decreased the integration time necessary to detect Raman signal from natural surfaces.

Landers and rovers are important to solar system exploration, and we are designing and analyzing a remote Raman system for a planetary mission. Raman spectroscopy is a common and powerful technique for materials analysis. We have developed a system that enables Raman spectroscopic measurements at distances of more than 50 meters. In order to design a flight instrument, we need to quantitatively understand the Raman efficiency of natural surfaces. We define remote Raman efficiency as the ratio of radiant exitance leaving a natural surface to the irradiance of the incident laser. The radiant exitance of a natural surface is the product of the sample radiance (minus background), the projected solid angle in steradians, and the spectral bandwidth of the spectrometer. The laser irradiance is the product of the energy of the laser (mJ/pulse) and the pulse rate (Hz), divided by the area of the laser spot. We have determined the remote Raman efficiency for several minerals and rocks: dolomite marble, dacite, milky quartz, anorthosite, calcite, biotite granite, magnesite, chert, gypsum (selenite), fibrous gypsum, and sandstone. By quantifying the remote Raman efficiency, we will be able to determine the number and quality of spectra that a remote Raman system can acquire on a planetary surface where available power is limited. Studies on hematite indicate that Raman shift (and thus remote Raman efficiency) depends on laser wavelength.

For a plasma light source based on a magnetically compressed discharge operating in a regime with a discharge-current pulse width equal to 1 s, induced by an electric power of about 1 MW, the possibilities are investigated of forming the time dependence and energy characteristics of radiation supplied from a network thyristor rectifier with an output voltage of about 500 V and a discharge current of up to 6000 A. It is shown that increasing the fraction of easily ionizable elements (Na, Ca, La) in the composition of the plasma-forming material increases the radiant exitance of the plasma radiator. The optimum induction of the compressing magnetic field is found.

Based on a magnetically compressed discharge with an electromagnet, a high-power plasma radiator capable of operating in the pulsed, continuous, and combined regimes has been created. The radiant exitance of the discharge plasma reaches 2×105W/cm2 in the pulsed regime and 104W/cm2 in the continuous regime.

This paper describes the design and technical characteristics of a wide-format radiator based on twenty special xenon tube lamps that makes it possible to irradiate objects up to 1m2 in area. The required amplitude-time characteristics of the radiant exitance of the radiator are formed by computer profiling the current pulses in each lamp. A thyristor line-supply system with electric power 3 MW is used in this case to generate one-second light pulses. Data are given on the structure of the radiator's light field and the results of physical modelling of pulses of complex shape with maximum irradiance 350W/cm2. The radiator is intended for studies of the action of powerful light on optoelectronic devices and optical and structural materials.

A model is described which determines pyrometer measurements of the temperature of silicon wafers. The wafers may have any combination of silicon polysilicon and 2 on it. The inputs to the model are the wavelength range of the pyrometer temperature film thicknesses and order doping levels and polysilicon grain size. Experimental data provides qualitative agreement to the model. Since the emissivity of the wafer is shown to generally vary with radiation wavelength conventional multi-wavelength pyrometry does not have any obvious ways of compensating for measurement differences due to varying wafer structures. However there may be an empiricalbased alternative for multi-wavelength corrections. 1 Background As rapid thermal processors find their way into commercial applications they are likely to face increasingly tighter requirements in the control of the transient and steady state temperature of the wafer. To achieve this level of control accurate closed loop temperature control is necessary for many commercial applications of rapid thermal processing. The temperature measurement tool usually employed in these closed loop control systems is one or more pyrometers. Pyrometers determine the temperature of the wafer by measuring the magnitude of the radiation being emitted from the wafer. The relationship between temperature and spectral radiant exitance can be expressed as follows: [7] M (1) where M is the spectral radiant exitance of the wafer Mb is the spectral exitance of a black body (both measured in Watts/rn3) and

Both surfaces of fine ceramics used for electronic parts are covered with, for example, a resin, a ceramic alumina, or a solder. An automatic optical method for detecting cracks originating at the side faces of ceramic chips, the surfaces of which are covered with the men- tioned materials, is developed and is reported. A laser beam is diffused into the specimen by illumination onto the side faces through an objec- tive lens. When the specimen has a crack near the laser spot, the dif- fused laser light is reflected by the crack and the amount of radiant exitance near the crack is increased. The image of the side face is en- larged by the objective lens and detected by four photomultiplier tubes. It is clarified experimentally that it is possible to recognize the region sur- rounded by a close-ended crack wider than 20 mm and longer than 35 mm, or an open-ended crack longer than 50 mm, by detecting signals higher than the average level. Experimental results revel that the cracks in the ceramic parts can be detected automatically in a production line. © 2003 Society of Photo-Optical Instrumentation Engineers. (DOI: 10.1117/1.1553451)

Scaled versions of a variety of silicon light-emitting diode elements (Si LEDs) have been realized using a standard 1.2-µm, doublepolysilicon, double-metal, n-well CMOS fabrication process. The devices operated with a n+p junction biased in the avalanche breakdown mode and were realized by using standard features of the ORBIT FORESIGHT design rules. The elements emit optical radiation in a broad band in the 450- to 850-nm range. An emitted intensity (radiant exitance) of up to 7.1 µW/cm2 (or about 8 nW per 60-µm-diam chip area) has been obtained with 5 mA of current at an operating voltage of 18.5 V. Excellent uniformity in emission intensity of better than 1% variation was obtained over areas as large as 100x500 µm. A best power conversion efficiency of 8.7x 10-8 and a quantum efficiency of 7.8x 10-7 were measured. All of these values are about one order of magnitude better than previously reported values for Si LED avalanche devices. Coupling between the elements as well as electro-optical coupling between an element and an optical fiber was realized.

The spectral radiant energy of a magnesium–sodium nitrate pyrotechnic flare is compared with theoretical spectra computed using radiative-transfer theory. The radiant energy over the range 3800–7400 A is 1.0×107 J, which is about 15% of the total energy of the flare reaction and about 25% of the energy available for radiation. The measured luminous efficacy is 37 lm/W. The experimental spectrum is shown to be consistent with a theoretical model in which the flare flame is a system of thermally excited sodium atoms from which the radiant exitance is radically influenced by radiative-transfer effects.