Infrared filters

Figure 9.12 Experimental setup (Nd YAG) Nd YAG laser (1064 nm, 50 Hz, 8 ns), (S) sample, (P) polarizer, (A) analyzer, (WP) waveplate (half or quarter rotated by steppermotor), (VF) visible-light-blocking filter, (PD) photodiode, (PMT) photomultiplier tube, (IRF) infrared filter, (IF) 532 nm interference filter, (PC) PC for data recording and control of the setup, (BC) boxcar/gated integrator, solid (dotted) line represents light at 1064 nm (532 nm).

K. R. Armstrong and F. J. Low. Far-Infrared Filters Utilizing Small Particle Scattering and Antireflection Coatings , Applied Optics, Vol. 13, No. 2, pp. 425-430, February 1974. 

FIGURE 3.9 Circulating water photoreactor system for determination of photomicro-biocidal activity under water flow conditions, a, reinforced membrane used in the study b, water jacket, continuous flow, infrared filter c, light source d, air pump e, bacterial air filter f, 3-way tap/pressure release g, 2-way taps h, frit for aeration J, peristaltic pump k, reservoir 1, ground glass Joints for ease of cleaning and sterilization (Bonnett et ai, 2006). 

The emitting species for sulfur compounds is excited S2. The lambda maximum for emission of excited S2 is approximately 394 nm. The emitter for phosphorus compounds in the flame is excited HPO with a lambda maximum equal to doublet 510-526 nm. In order to detect one or the other family of compounds selectively as it elutes from the GC column, the suitable band-pass filter should be placed between the flame and the photomultiplier tube to isolate the appropriate emission band. In addition, a thermal infrared filter is mounted between the flame and the photomultiplier tube to isolate only the visible and UV radiation emitted by the flame. Without this filter, the large amounts of infrared radiation emitted by the combustion reaction of the flame would heat up the photomultiplier tube, thus increasing its background signal. 

The spectral dependence of the light sensitivity (as indicated by yellowing) of free films of Parylene-C was determined. A Heraeus Sun-Test chamber, equipped with a xenon arc lamp filtered to yield a simulated solar spectrum, was used for the irradiation. An additional infrared filter minimized sample heating. The irradiance at the sample location was originally 0.83 W/m2 at 340 nm, but the output decreased approximately 20% after 1500 hours use. Long band-pass optical filters with nominal cut-offs of 305 nm, 345 nm, 385 nm and 400 nm were inserted between the xenon lamp and the Parylene-C film samples to determine the wavelength threshold for yellowing. The sample temperature was maintained at 30+ 2 °C with a water-cooled... 

Infrared Filter For Photo Light Sources, Sniperscopes, Signaling Alarrh Systems... 

Fig. 24. KineticaDy measuring reflectometer in the Ektachem. 1 stepping motor, 2 lens system, 3 filter rotor, 4 lens system (collimator), 5 slide in the incubator, 6 filter, 7 aperture, 8 spheric mirror, 9 quartz halogen lamp, 10 objective lens system, 11 infrared filter, 12 mirror, 13 diaphragm, 14 photodetector.

Also, films of amorphous semiconductors have found optical applications for example, in multilayer infrared filters or as antireflective coatings. 

Rodriguez 1, Fenollosa R, Meseguer F (2010) Silicon microspheres as UV, visible and infrared filters for cosmetics. Cosmet Toilet 125(9) 42-50... 

Mesoporous Si nanoparticles DPBF decomposition Tjso 10 % in ethanol, Tlso 17 % in water White light (infrared filtered), 100 mW/cm, 10 min liquids with dissolved O2, RT Xiao etal. 2011... 

D. Burdick, F. E. Barton n, and B. D. Nelson, Rapid Determination of Forage Quality with a Near Infrared Filter Spectrometer, in Pwc. 36th Southern Pasture a Forage Crop Improvement Conf, BeltsviUe, Maryland, May 1979, pp. 81-86. 

N. L. Alpert, Infrared Filter Grating Spectrophotometers—Design and Properties, Appl. Opt. 1 437 (1962). 

Fig. 3. Comparison of relative sensitivity of photographic emulsion associated with Wratten filters (15,25A, 58, and 89B)- 1. Panatomic X and filter 58 (green) 2 Panatomic X and filter 25A (red) 3 Infrared black and white and filter 89B (dark red) 4, 5, and 6 Ektachrome infrared, filter 15 (orange), 4 yellow dominant 5 magenta dominant 6 cyan dominant (sensitive layers before exposure).

Multispectral photographs, Apollo 9. Two photographs from the group of four, or C (black and white infrared, filter 89B) and D (Panatomic X, with filter 25A). The geological aspects, despite the plant covering, appear sharply on the two photographs, while hydrography shows up on plate C. 

Conductive grids may also serve as optical filters in the far infrared (Vogel Genzel, 1964). A variety of techniques are used in their construction. Evaporated or electrochemically deposited metals on dielectric, transparent substrates (mylar, quartz) can be used, or simply a flat metal foil with patterns of small holes punched into it. Woven wire grids, such as commonly employed as sieves, can serve double duty as far infrared filters. With electroformed or vacuum deposited grids it is possible to construct two complementary versions, inductive and capacitive grid patterns (Smith et al, 1972). 

Smith, S. D., Holah, G. D., Seeley, J. S., Evans, C., Hunneman, R. (1972). Survey of the present state of art of infrared filters, hi Infrared Detection Techniques for Space Research, ed. V. Manno J. Ring. Dordrecht, Holland D. Reidel Publ. Co. 

Electro Optical Components Inc Web Site (2014) by Electro Optical Components, Inc., Santa Rosa, CA. Accessed April 2014 at http //www.eoc-inc.com/infrared source.htm. Sources and Pyroelectric Detectors, Thermopile Detectors, Infrared Filters. 

---