Light trapping

Pritchard D E, Raab E L, Bagnato V, Wieman C E and Watts R N 1986 Light traps using spontaneous forces Phys.Rev.Lett. 57 310-13... 

Photomultipliers are used to measure the intensity of the scattered light. The output is compared to that of a second photocell located in the light trap which measures the intensity of the incident beam. In this way the ratio [J q is measured directly with built-in compensation for any variations in the source. When filters are used for measuring depolarization, their effect on the sensitivity of the photomultiplier and its output must also be considered. Instrument calibration can be accomplished using well-characterized polymer solutions, dispersions of colloidal silica, or opalescent glass as standards. 

Absolute photoluminesccnce efficiency measurements in thin solid films are quite difficult, since light-trapping, waveguiding effects and, possibly, distributions in the emission dipole moments of individual chromophorcs modify the angular distribution of the emission. Dc Mello el al. ]126] have described an improved mclh-... 

Textured Tin Oxide Films Produced by Atmospheric Pressure Chemical Vapor Deposition from Tetramethyltin and Their Usefulness in Producing Light Trapping in Thin-Film Amorphous Silicon Solar Energy Mater., 18 263-281 (1989)... 

A thin film of tin oxide with a rough texture, produced by MOCVD from tetramethyl tin, (CH3)4Sn, deposited on an amorphous silicon cell provides a light-trapping surface, which enhances the efficiency of the device. 

We have developed another bench for the measurement of the contrast value. Contrast measurement have been carried out on the MMA fabricated by Texas Instrument, in order to establish the test procedure (Zamkotsian et al., 2002a Zamkotsian et al., 2003). We can address several parameters in our experiment, as the size of the source, its location with respect to the micro-elements, the wavelength, and the input and output pupil size. In order to measure the contrast, the micro-mirrors are tilted between the ON position (towards the spectrograph) or the OFF position (towards a light trap). Contrast exceeding 400 has been measured for a 10° ON/OFF angle. Effects of object position on the micro-mirrors and contrast reduction when the exit pupil size is increasing have also been revealed. 

Blue n.s. n.s. microscope light [0]b [LDn]d [L-ns]e Light trap. Visual evaluation Cohn 9) ... 

Projected prism spectrum through slotted screen Projection lamp of 2000 candles. Dim light6 [V] [LDn ] [L-ns] Single light trap method. Visual evaluation Oltmans76)... 

Interference filters with 7-17 nm band width 6 V microscope lamp [M.PBZ-G4 from B]11 [DDJ [Ld-2]. Light trap. Visual evaluation spectra shows activity of cells (as a function of intensity) after 6 min Gossel44)... 

Filter combinations with 40 nm band width 20 W fluorescent tube. 15 ft candles constant incident intensity [Gracilis] [LL] [Li]. Double light trap selection method. Relative accumulation after time. Visual evaluation. Wolken and Shin109)... 

Interference filters with 7-17 nm band width Tungsten lamp [G] [LDi] [L-ns]12 Phototaxigraph (light trap). Rate photoaccumulation. Spectrum is relative response to that at 499 nm corrected for incident quanta Diehn and Tollin29)... 

Constant deviation spectrophotometer 80 W tungsten lamp [V) [LDn] [Lns]16 Double light trap. Visual evaluation. Mast... 

When an organism leaves a photosystem II light trap, the flux into the electron pool decreases. 

When a trichome moves into a photosystem I light trap, electrons are drained out of the pool. In both cases a phobic response is caused, but different patterns result, one being an accumulation in, the other a dispersal from, the light trap l0]). 

Microscopic analysis of the photobehaviour demonstrated that phobic responses are inhibited only in those organisms which move more or less parallel to the electric field lines. In those leaving the light trap perpendicular to the field lines, the phobic responses were not impaired. But since the light trap was not completely closed, no accumulations were formed. 

Fig. 13. Three-dimensional representation of the effect of voltage and frequency of a rectangular wave on photophobic accumulations in 1000 lx white light traps. Left abscissa peak-to-peak voltage Right abscissa frequency in Hz Ordinate response in % of the uninhibited control (after Hader44))...

Fig. 15a-c. Effect of TPMP+ on (a) light-induced potential changes (Left ordinate in % of uninhibited control), (b) on photophobic accumulations in light traps (Center ordinate in % of uninhibited control) and (c) resting potential (Right ordinate in mV). Abscissa TPMP+ concentration in mol (after Ha-der48))... 

The experiments on the iodine separation were conducted as follows. A tubular vessel of pyrex glass, having at one end a plane window and at the other end a conical light-trap, was evacuated and then filled with iodine at about 0.17 mm. pressure, and then with hexene at about 6 mm. partial pressure. The tube was then subjected to the intense light from two Cooper-Hewitt glass mercury arcs, using a filter of 0.05 molal potassium dichromate 2 cm. in thickness to cut off all radiations on the violet side of the green mercury line. The lamps were rim at considerably below the rated capacity, and were cooled by a blast of air to keep the emission lines as narrow as possible. 

Keever, D.W. and Cline, L.D. 1983. Effect of light trap height and light source on the capture of Cathartus quadricollis (Guerin-Meneville)(Coleoptera Cucujidae) and Callosobruchus maculatus (F.)(Coleoptera Bruchidae) in a warehouse. J. Econ. Entomol 76, 1080-1082. 

---