Mounting light sensors

The light-sensing package features bare chip mounting for sensor installation on the instrument panel. Fig. 7.13.16 shows the assembly structure of the light sensor. The light sensor device is bonded to the middle terminal and then wire-bonded to the outer terminals. The top of the device is coated with gel to protect the A1 wire. Chip capacitors for EMC are bonded between terminals with conductive adhesive. 

Table 9 shows the summary of the present status of ozone sensing[6]. From the view point of global environment, a major need for ozone sensing lies in the measurement of ozone concentration in high altitude of atmosphere. Especially, small and light sensors which can be mounted on a sonde or a rocket are desired. Liquid electrolyte sensors are being used now for such... 

Laser alignment systems use a transmitter and receiver. The system has a laser diode and a position sensor on a bracket mounted on one shaft that emits a weak and safe radio-tagged beam of light. The light ray is directed toward the other bracket on the other shaft with a reflecting prism that returns the ray back toward the first bracket into the position sen.sor eye. 

Measurement by means of a wall optical sensor The thickness of a film and the slope of its free surface can also be measured by means of a wall optical sensor, as proposed by Ohba et al. (1984). This sensor consists of a cluster of seven optical fibers mounted flush with the wall (Fig. 3.33). A laser beam passed through the central fiber is reflected by the free surface onto the other fiber tips, which collect the light and transmit it to two photodiodes. The light intensities received by these two detectors enable the film thickness and the inclination angle to be determined. 

The containers for water softener and clarifiers are situated in the door of the dishwasher. The reed sensor is mounted next to the plastic casing that contains a magnet in a protective foam housing, floating on the liquid. When the level drops to a certain point, the floater activates the reed sensor, which in turn directly operates an indicator light on the front panel. The operator of the dishwasher is then alerted that softeners and/or clarifiers need to be refilled. 

A reed sensor is mounted either above or underneath the spray-arm, outside of the washing area, while a magnet is placed on the spray-arm. The reed sensor counts the revolutions of the spray-arm. If for any reason the spray-arm is not working (Dishes inside the dishwasher could block the movement, or the spray-arm is faulty, etc.), the sensor will indicate on a small outside light or display that service is needed. An additional electronic device could also be activated with this reed sensor to stop the machine, so that the dishes or the machine itself will not be damaged. 

To replace the old-fashioned eye-control method of detecting the level of the liquid, appliance manufacturers now use reed sensors to show when the container for Jet-Dry needs refilling. The reed sensor is mounted underneath, or next to, the liquid container. A floater with an internal permanent magnet is placed in the container and floats on the liquid. If its level falls to a minimum, the floater activates the reed sensor which, in turn, activates a light on the front control panel of the dishwasher, signaling the need to refill the Jet-Dry container. 

The remedy to this is to place the resonance frequencies of the bodywork and the sensor as far apart as possible, and to make sensors with high working frequencies. The mounting of mechanical dampers to prevent transfer of the bodywork resonance frequencies to the sensor is common practice. Mechanical dampers within the sensor itself are also used. Typical working frequencies for yaw-rate sensors are 2-40 kHz, bodywork and printed circuit board resonance frequencies are typically below 5 kHz, or for very stiff light metal bodywork, up to 20 kHz. 

A large field for optical biosensor modules is their use in analytical flow systems, either with special optical cells within the instrument or with optical fibers for remote measurement. An optoelectronic biosensor , proposed by Lowe and Goldfinch [224], is a flow-through cell mounted in a compact device between a light source and a photodiode, containing enzyme-indicator membranes (eg, with penicillinase and bromocresol green). The linear response of this flow sensor is between O.S and 5 mM substrate. 

In the fiber-optic thermometry probe technique, a temperahue sensor, consisting of a small amount of a temperature-sensitive material (manganese-activated magnesium fluorogermanate), is mounted on the end of a probe and is placed on the surface of the device under test (DUT). A filtered xenon flash lamp provides a blue-violet light to excite the phosphor on the probe to fluoresce. When excited by this wavelength of light, the phosphor in the sensor exhibits a deep red fluorescence. 

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