Detectors

This modular range of broadband light meters and radiometers offer the possibility of individual configuration. Customers can choose from a wide selection of optometers, amplifiers, detector heads and accessories. In addition to its standard products, Gigahertz-Optik also offers customized solutions.

Step 1: As a first step we recommend the selection of a detector head. It is also possible to use several detector heads, which can be used interchangeably with single-channel meters or simultaneously with multi-channel meters. The selection criteria for a detector head include the required measurement quantity and range, its spectral function, and all other parameters relevant to the intended use.

Step 2: In the second step, accessories such as e.g. an integrating sphere can be selected. If the accessory changes the detector head’s measurand geometry and responsivity, an additional calibration for the detector head with accessories in the corresponding measurand must be selected.

Step 3: In the third step, the meter is selected. The planned use (e.g. mobile, stationary, manual or remote-controlled), the number of signal channels, the measurement  mode (CW, dose, pulse energy, temporal pulse progression) are all decision criteria.

Step 4: The connection of the measuring device for the detector head determines the connector type of the detector head. Gigahertz –Optik’s detectors are designed with connectors of the following four types:

• Connector Type -1: Conventional BNC coaxial connector        
• Connector Type -2: Calibration Data Connector with Eeprom for storing the detectors data (type, calibrated responsivity) read by the connected meter.
• Connector Type -4: Compact plug for detector heads with up to four photodiodes.
• Connector Type -5: Compact plug with calibration Eeprom

Step 5: To determine the measuring range of a selected configuration, some specifications of the selected detector head and meter are required. The typical sensitivity (e.g. A/lx) and the max. permissible signal current of the detector head and the minimum and maximum input signal of the measuring range of the meter.

Detection Limit (Noise Equivalent Power, N.E.P.) = Minimum input signal of the meter (A) / typical detector sensitivity (e.g., 0.1 pA / 3 nA / (mW / cm²) = 0.33 nW / cm². ^{(*1) (*2)}

Maximum reading = maximum input signal from the meter (A) / typical detector sensitivity (e.g., 20 μA / 3 nA / (mW / cm²) = 6.66 W / cm². ^(*3)                                                                                                                                           

Remarks:                                                                                                                                                   

^(*1) The minimum measurable value of the broadband light meter or radiometer results from the desired signal-to-noise ratio (SNR). For a DIN Class A lux meter, e.g. a minimum SNR of 100 is given. For the detector head of the example calculation, an SNR of 100 would mean a minimum measureable value of 33 nW / cm². For applications in the limit area of optical radiation measurement technology, it is common to use lower SNR of 50 or even 10.                                                                                                                                                

^(*2) In the case of very low detector current signals, movements of the cable between the detector head and the meter can lead to short, capacitive interference signals. In addition, strain effects on the plug of the detector head may increase the noise signal.                                                                                                                                         

^(*3) The maximum calculated measurement value reflects the large dynamic range of semiconductor photodiodes. In practical application, however, the maximum measurable value is often limited by the temperature radiation contained in the measured optical radiation, which would mean unacceptable heating of the detector head.