A Camera Using

R) Pbotoelectric Cell Camera. A camera using a photoelectric cell as a source of illumination. 

A sensor may be thought of as consisting of two parts the transducer which converts a chemical signal to an electronic signal, and a chemically selective layer which interacts directly with the sample. A transducer itself usually does not have the selectivity, dynamic range, or sensitivity required for many measurement applications. Just as a camera uses different lenses for telephoto, macro, or wide-angle shots, a transducer requires the cooperation of a chemically selective material in the form of a coating, membrane, or electrolyte to measure different species in different applications. These materials serve as a selective receptor to mediate between the outside environment and the sensor s transducer. 

Fig.1 Schematic of the LAPAP optical setup. Two mirrors, M1 and M2, are used to adjust the beam direction, before it reaches the sample. The back-reflection from the coverslip is directed to a camera using a wedge window, W1. The image is focused by alens, L2,to monitor the position of the laser focus on top of the sample surface (color figure online)...

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