Package photodiode

Most UV photodiodes have a sealed metal TO package with an entrance window made of glass or special UV-transmitting glass. A TO housing is extremely reliable but it often counts for a non-negligible part of the sensor costs. Cheaper housings that should be favored for consumer-product applications like in household appliances are hard to find. Full-plastic encapsulation requires a UV-transpar-... 

A popular UV sensor designed for flame monitoring is the SFH 530 sensor by Infinion. It is a UV-enhanced Si photodiode with optical filter, concentrator lens and operational amplifier in a TO-39 package. Flame-sensing in gas ovens is another potential application of the described technique. 

Photodiode detectors have already been cited in this chapter in relation to near-IR fluorescence measurements on singlet oxygen,(8 16 18) in decay-time temperature sensing,(50) in liquid chromatography,(62) the study of proteins labelled with Nile Red,(64) and diode laser spectrometry,(67) Photodiodes are also conveniently packaged for many applications in an array form enabling rapid data acquisition e.g., in spectrophotometry, (35)... 

Photodiode array (PDA) detectors are becoming more popular as their ability to use both retention times and UV spectra to aid in peak identification becomes more widely recognized. With most PDA software packages, libraries of standard compounds can be created by the analyst. When samples are run, the spectra and/or the run times of the peaks in the sample can be compared with those stored in the libraries. Because the shapes of UV spectra are dependent on the experimental conditions under which they are obtained, however, it is unlikely that standard libraries will become commercially available. 

As an example, linear arrays of silicon photodiodes (photodiode arrays) are available as a package complete with the necessary circuitry to read out the array following exposure. Arrays are available with up to 2048 elements, and they are read out on an element by element basis. The scanning circuitry can access an element in 10 - 25 /rs, which suggests that the entire array can be read out in approximately 20 - 50 ms. Thus modulation frequencies can not exceed 50 Hz. However, as was discussed earlier, PEMs are driven at a resonant frequency which usually varies between 50 and 100 kHz, and this exceeds the readout rate of the photodiode array by three orders-of-magnitude. 

The sensing demonstration described above was realized in normal transmission, which is much simpler than the typical angled reflection arrangement employed in the commercial SPR systems. This transmission setup is more compatible to the lab-on-chip concept, since miniaturized light sources, such as LEDs, and photodiodes (or a CCD) can sandwich the sensing areas of the array of nanoholes, yielding a compact package. 

Photodiodes are used as detectors in many automated systems either as individual components or in multiples as an array. Photomultiplier tubes are required in many immunoassay systems to provide adequate sensitivity and fast detector response times for fluorescent and chemiluminescent measurements. Several approaches have been used for the electrooptical integration and packaging in different analyzers. A logarithmic amplifier or microprocessor and/or computer software converts transmittance to absorbance. Low-cost analog-to-digital converters with conversion times... 

The photodiode array detector is connected to a computer fitted with a suitable package to control the method, calculate and report the results. The photodiode array detector consists of 1000 or more silicon photodiodes arranged side by side on a single small silicon chip and absorption of electromagnetic radiation by a pn-junction causes promotion of electrons from the valence bands to the conduction bands and thus the... 

Precision alignment and attachment of optical fibers to couple them with lenses, transmitter and receiver components, and laser diodes is stiU largely a manual, labor-intensive process. Optical fibers must be aligned to insure that the optimum amoimt of light is transmitted between the fiber on the outside and the laser, photodiode, or other optical component on the inside of a package. Alignment may be active or passive. ... 

The photodiode is a semiconductor diode that functions as a photodetector. Photodiodes are packaged with either a window or optical fiber connection, in order to let in the fight to the sensitive part of the device. They may also be used without a window to detect vacuum UV or X-rays. 

Fig. 3. Detail measuring setup for pnit optimal distance between optical PIN photodiode in SMD package and output facet of the planar optical pwlymer waveguide...

These areas are a mixed bag relative to the corresponding areas with a diode laser. In several respects the tasks are easier with an external modulator. There is no junction, at least when the modulator is fabricated in either an inorganic or a polymer. Thus, there is no need to maintain a specific operating temperature, which eUminates the need for a TEC and thermistor. Also there is no feedback of optical power, which eUminates the rear facet photodiode commonly found in a diode laser package. 

If a Radio Shack catalog number 276-142 photodiode is used, the package looks like the one on pagel67 of this book. What is shown as the emitter on that page becomes the small triangle of the diode on page 252, where "positive... 

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