Instrument Systems has developed a modular IR test solution that meets the requirements of optical under-display fingerprint sensors with wavelengths above 1100 nm. In smartphones, under-display fingerprint scanning is widely used to unlock a device comfortably and safely. The light output used for this application was previously at a wavelength of around 940 nm. Unfortunately, at this specific wavelength burn-in phenomena occur in OLED displays. A solution for this disadvantage is to use radiation at 1380 nm. As the application stays the same for the user, the shift from lower to higher wavelengths in the NIR requires other high-resolution and calibrated test equipment for the precise measurement of radiometric quantities, pulse measurement in the µs range and temperature control.
The core of the system is the model IR1 spectroradiometer, which is optimised for wavelength measurement in the near infrared range. With a cooled InGaAs line sensor, the instrument has a wavelength range from 780 nm to 1650 nm and features thermoelectric cooling of the sensors down to a temperature of –10° C. The high-gain option enables the sensitivity range to be significantly extended to include low power applications. A high-resolution model with a wavelength range from 1300 nm to 1440 nm additionally enables detailed investigation of narrow-band radiation sources with an optical resolution <1 nm.