Transmission filter

The protection current produced by the usual full-wave rectifier has a 100-Hz alternating component of 48%. There are receivers with selective transmission filters for 100 Hz, which corresponds to the first harmonic of the cathodic protection currents [45]. With such a low-frequency test current, an inductive coupling with neighboring pipelines and cables is avoided, which leads to more exact defect location. 

Multicavity filters. Multicavity Fabry-Perot filters are used to make very narrow transmission filters. A simple Fabry-Perot cavity (see Ch. 2) consists of a halfwave layer surrounded by two reflectors of typically 10 layers each. Figure 4 shows three transmission profiles obtained with one, two or three cavity filters. The three cavity HL) 5HH(LH) 5) " 3 filter has a 1.2 nm bandwidth. It has 60 layers. Note that the three-peak top of the transmittance. Each cavity has to be well adapted to the following one if not the resulting transmittance can be very poor. Such cavities are broadly used in telecoms in between arrays of antennas for cell phones. 

Color from red, green, and blue emitters Color from blue emitter with phorsphor filters Color from white emitter with transmission filters... 

The chip with dried spots was covered with a UV transmission filter, and then placed into UV crosslinking instrument. 

Surface-introduced photoreactive group, aryl diazirine, can generate carbenes by 365 nm UV exposure. However, gold-sulfiir bonds, which support photolinker on gold, can be easily broken by UV light below 300 nm. Therefore, UV transmission filter is essential in UV irradiation. 

In UV reflected photography, a light source emitting ultraviolet light is directed at the subject which then reflects this radiation into the camera. Visible radiation from the room or reflected from the subject will be absorbed by an ultraviolet transmission filter over the camera lens thereby preventing any visible light from reaching the film. 

In UV fluorescence photography, the fluorescence of a substance excited by UV illumination is captured. The source of ultraviolet radiation filtered with an ultraviolet transmission filter, or excitation filter, is aimed at the subject in a completely darkened room. The subject reflects the ultraviolet light, but can also emit a visible fluorescence. The ultraviolet light is then prevented from reaching the film by a barrier filter that only allows visible light to be transmitted to the film. 

Scanning transforms the photographic pattern into an optical density map of the region scanned. Transmission is measured at intervals spaced equally. The photometer output voltage, calibrated against a standard transmission filter set yields values proportional to the energy absorbed by the film, and therefore... 

Figure 5. Visible laser stability. The laser power fluctuations using a 488 nm (blue) and 568 nm (red) lasers were determined using a 10x objective and a Chroma red slide. The fluorescence was sequentially measured every 30 sec (400 times) for total time duration of 3.33 hrs. The variation of the peak to peak using 488 nm or 568 nm excitation was approximately 25%. The fluctuating power intensity line suggests that the system scanning and detection devices are yielding large power fluctuations that will affect the illumination of the sample. The Acousto Optical Transmission Filter (AOTF) is probably contributing to this 488-568 nm sinusoidal pattern.

These fluctuations also occur when there are temperature or instabilty problems in the Acousto Optical Transmissions Filter (AOTF) of Laser Scanning Confocal Microscopes (LSCM), or when there is incorrect... 

Example 1 Substance of known triple-point in a triple-point cell Example 2 Glass of known optical density in a transmission filter holder Example 3 Spheres of uniform size mounted on a microscope slide. 

Fig. 4.1. Schematic of an experimental set-up for absorption measurements at low temperature incorporating a Perkin-Elmer Model 99G monochromator. Si, S2 and S3 are IR sources selectable with plane mirrors Mi and M2. FM focusing spherical mirrors. Ei and E2 entrance and exit slits. CM off-axis paraboloid collimating mirror. G plane reflection grating. Beam 1 from Si is converted by CM into a parallel beam dispersed by G. One wavelength is diffracted in a direction where it can be intercepted by first mirror M as beam 2 and focused on the internal chopper Ch. Modulated beam 2 is redirected toward G as beam 3 and re-dispersed a second time as beam 4. Beam 4 intercepted by IM is focused on E2 and re-focused on the sample by FM. The divergent monochromatic beam is finally focused on thermocouple D by ellipsoidal mirror EFM. Fi, F2 and Pol are locations for transmission filters and a polarizer. Beam 1 can be blocked by shutter Sh (after [37]). With permission from the Institute of Physics...

One method used to isolate a X-ray line from unwanted background and noise, employs equilibrated filters. It consists of linking the concentration of interest to the difference between two measurements. The first is obtained by installing a transmission filter between the sample and the detector to isolate the characteristic radiation of the element wanted and the second by fitting an absorption filter which is opaque to this same radiation. This will enable, for example, to quantify the copper from its main spectral line by using two filters, one made of nickel and the other made of cobalt. The fluorescence originating from the filters themselves is a limiting factor in this method, which is reserved for routine measurements. 

F. Bilodeau, K. 0. Hill, B. Malo, D. C. Johnson and J. Albert, High-retum-loss narrowband all-fiber bandpass Bragg transmission filter, IEEE Photonics Tech. Lett., 6 [1], 80-82 (1994). 

In laser spectroscopy, etalons are mainly used as wavelength-selective transmission filters within the laser resonator to narrow the laser bandwidth (Sect. 5.4). The wavelength or frequency for the transmission maximum of mth order, where the optical path between successive beams is = mX, can be deduced from (4.46a) and Fig. 4.36 to be... 

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