Technical Notes

Thermopile Sensor Physics

Technical Notes

Thermopile sensors are based on thermocouples. A thermocouple consists of two dissimilar metals connected in series. To detect radiation, one metal junction is typically blackened to absorb the radiation.

Pyroelectric Sensor Physics

Technical Notes

A pyroelectric crystalline material has electric polarization even in the absence of an applied voltage. On heating, the material expands and produces a change in the polarization which builds up a charge on the opposite surface.

Photodiode Sensor Physics

Technical Notes

A photodiode sensor consists of a semiconductor p-n junction. Light falling on the junction causes the formation of electron-hole pairs. In photovoltaic mode, the electron-hole pairs migrate to opposite sides of the junction, producing a voltage.

LED Characterization

Technical Notes

Measurement techniques of the power, flux (equivalent to power but measured in units of lumens), and spectrum of LEDs is not very different from that of traditional light sources.

Laser Beam Spatial Profiles

Technical Notes

The irradiance distribution of a laser beam is determined by the transverse modes that exit the laser cavity. Typically, the lowest-order transverse mode (TEM00) is selected for emission since it propagates with the least beam divergence and can be f...

Incoherent Light Source Physics

Technical Notes

The incoherent light sources discussed here share several characteristics that distinguish them from lasers. Incoherent light gives rise to radiation, which is emitted from the source in all directions.

Radiometric Measurement

Technical Notes

Radiometry is the measurement of energy or power in electromagnetic radiation fields or light. The average output power is the most common radiometric measurement since many light sources, including CW lasers and LEDs, emit output power that is const...

Photoreceiver Characteristics

Technical Notes

The characteristics of such high-speed photoreceivers as well as their associated applications are the subjects of this technical note.

Types of Photoreceivers

Technical Notes

The main types of photoreceivers are those that can detect optical signals with fast temporal responses or those containing high frequency components.

Laser Beam Profile Measurement

Technical Notes

Given the different types of laser beam spatial distributions and their evolution as they propagate in free space and through optical elements, measurement of the beam profile is critical to quantify the irradiance at the point of the application.
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