FAQ

The detector risetime / falltime is calculated by that formula: tr/f = 2 Pi RC with R = internal resistance of the photodiode and C = capacitance of the photodiode. Example = a typical value of R is 5 Ohm and the C value for a SG01S-18 photodiode is 15 pF. This calculates: with R = internal resistance of the photodiode and C = capacitance of the photodiode tr/f = 2Pi * 5 Ohm * 15 * 10-12 F = 0.47 * 10-9 s = 0.47 ns.

The saturation current I_sat of a photodiode is determined by its open circuit voltage VOC and its serial resistance RS following the formula:
I_sat = VOC / RS
A typical value (SiC photodiode) for VOC is 2.0 V and for RS = 5 Ohm. This calculates: I_sat = 2.0 V / 5 Ohm = 0.4 A = 400 mA.
The saturation radiant intensity z calculates by the below formula: z = I_sat / (S * A)
Where S is the radiant sensitivity of a photodiode and A is the active area. A typical value for S is 0.13 A/W and A = 0.06 mm² (valid for SG01S). This calculates: z_sat = 0.4 A / (0.130 A/W * 6 * 10-8 m² ) = 51.28 MW/m² = 5.13 kW/cm²

Detailed further information is provided by the Hamamatsu „Chapter 2 of Handbook of Si Photodiodes“ to be downloaded from the Hamamatsu website.

Yes, f1,Z is smaller than 0.25.

Our UV photodiodes are hermetically sealed and can be used under vaccum, theoretically down to 0 Pa.

Our four filtered versions of the UV photodiode lead to a tighter sensitivity range.

A TOCON is a UV photodetector that contains a SiC or a GaP detector chip and an amplifier circuit that outputs a voltage of 0 to 5 V. This output voltage is linear in proportion to the UV radiation intensity reaching the chip.

Compared with a bare UV photodiode the TOCON’s big advantage is the amplifier’s position inside the TO5 metal housing and its close proximity to the detector. This construction protects the usually very low current levels generated by the detector chip from electromagnetic interference and also from moisture and pollution induced disturbances. A point to be considered of the TOCON is the lower dynamic range (approx. 3 orders of magnitude) compared with a SiC UV photodiode (10 orders of magnitude). To overdome this disadvantage we offer each TOCON type in many different amplification levels to avoid saturation and too low voltage output levels for nearly all applications.

A TOCON is smaller and much less expensive than a sensor probe. Additionally a TOCON is water pressure proof and hermetically sealed. A point to be considered is that at the presence of strong electromagnetic interferences or in case of excess voltage a sensor probe could be of a better performance. The reason is that a sensor probe contains more space that is needed for components that avoid problems caused by ESD or excess voltage.

The theoretical maximum signal output is always a little less (approx. 5%) than the supply voltage.

No, no additional amplifier is required.

Please use a standard voltmeter to read out the signal. Caution! Wrong wiring of power supply can lead to immediate destruction of the device. Please refer to our application note delivered with the device.

A TOCON is a sophisticated product with many internal components. Many of these internal components, and especially the quantum efficiency of the UV-sensing SiC chip and the gain resistor value, have sample to sample scatter (variation). TOCONs are designed for a total scatter of +/-20% in signal and some devices will show greater variance. It is recommended that that when choosing a TOCON model for production, the TOCON should be chosen so that the 5V saturation level is TWICE the expected signal from the device under normal conditions and that under normal/design conditions, output voltage is about 2.5V.

Customers are especially cautioned to AVOID SATURATION conditions. Saturation is when Signal voltage equals Power Supply Voltage (normally 5V). Saturation will not damage the TOCON but it can lead to PERSONAL SAFETY PROBLEMS or other DAMAGE due to unknown and potentially excess UV exposure levels.

The TOCON can drive resistive loads as low as 2 kOhms, but we recommend not to stress this limit unnecessarily. In normal environments an input impedance of >= 100 kOhm is recommended for the readout circuitry. In very harsh (EMI/EMC/noisy) surroundings impedances of >= 10 kOhm can be considered taking into account a slight reduction in output swing.

The TOCON is stable for capacitive loads up to 30 pF under all circumstances. If more capacitive loading can not be avoided a series resistor of 10 Ohms … 100 Ohms may be required to ensure stability up to few hundred nF.

No, the TOCON is not calibrated. If required, the sglux calibration laboratory offers an individual calibration service including a calibration certificate. This document assigns the voltage output of one specific TOCON to the irradiation of a specific UV radiation source.

As-delivered the TOCON is sensitive in the specified range. Example: A TOCON_ABC6 is sensitive between 180 nW/cm² and 1.8 mW/cm².
This means that the TOCON will saturate (output voltage = input voltage) at approx. 1.8 mW/cm². At the lower end a radiation of 180 nW/cm² will still output a couple of mV. While selecting a TOCON, the most important thing to consider is to not illuminate the TOCON until saturation level. A saturation will not damage the TOCON but likely the voltage output will no longer be linear to the radiation input because any increase of radiation above / below the saturation point will not further increase the output voltage.

The TOCON can drive resistive loads as low as 2 kOhms, but we recommend not to stress this limit unnecessarily. In normal environments an input impedance of >= 100 kOhm is recommended for the readout circuitry. In very harsh (EMI/EMC/noisy) surroundings impedances of >= 10 kOhm can be considered taking into account a slight reduction in output swing.

The TOCON is stable for capacitive loads up to 30 pF under all circumstances. If more capacitive loading can not be avoided a series resistor of 10 Ohms … 100 Ohms may be required to ensure stability up to few hundred nF.

No, the probe is not calibrated. If required, the sglux calibration laboratory offers an individual calibration service including a calibration certificate. This document assigns the voltage output or the current value of one specific probe to the irradiation of a specific UV radiation source. As-delivered the probe is sensitive in the specified range. Please find further details at the sglux website’s calibration section.

We can offer our UV-Cosine sensor for outdoor measurements. The housing is waterproof IP68 at window side, stain repellent and on request submersible.

Yes, temperature and UV signal is read and stored.

Yes, this works.

A numerical temperature compensation (compensation signal change with temperature) is possible, but not enabled. This would only be relevant for temperatures above 55°C.

13.75 Hz is intrinsic acquisition frequency of the sensors. Setting a lower rate for data logging (like 1Hz) is not a problem. The logging rate can easily be changed by the user.

The measurement data is stored inside the handheld unit. To read out the data please use the USB stick. Permanent read out via PC is not possible. Please use our DIGIBOX.

The temperature indicated by the UVTOUCH is the internal temperature of the Sensor. Due to heat generation (self heating) of the PCB the temperature is always a little above the ambient temperature. This temperature is mainly used for being able to exclude destructive temperatures above 85°C.

Photodiodes or UV sensors with voltage output (TOCON series, UV probes).

By default, the units input terminals are NIST traceable calibrated looking at the displayed voltage (Sensor connected) and current (Photodiode connected). If the Sensor Monitor is delivered in a bundle with an UV sensor, the Sensor Monitor will come calibrated. A calibration certificate is available on demand.

Our UVMICROLOG can be configured to be waterproof.

The current consumption of a Multiboard is between 4 mA and 20 mA, depending on the amount and type of operating voltage (uni / bipolar) as well as the load at the output (multimeter = no load).

sglux offers PTB-traceable (Physikalisch Technische Bundesanstalt) calibration.

The information shown on the calibration certificate is given by ISO17025 / DAkkS 71 SD 0 025.
A typical calibration certificate is given here (link). It contains the following information et al:
– Reference irradiation measured by a traceable-calibrated (spectro-) radiometer
– Calibration object signal
– Calibration factor [Signal]/[W/m²]

We recommend a recalibration every 12-18 months.

The measurement uncertainty depends on the wavelength range to be measured by the UV sensor. The minimum measurement uncertainties (k=2) are as follows:
200 – 249 nm     13%
250 – 299 nm      7%
300 – 399 nm      5%
400 – 430 nm      4%