The LIDAR Echo Emulator (LEE) emulates the returned signals from a Lidar system. As the return signal of a Lidar system depends on the target, this implies the capability of shaping the lasers returns. In brief, long echo corresponds to a natural or diffusive object (canopy, clouds) and short echoes to a hard object like roofs, ground, etc. Such signals are necessary to be simulated to study and validate new detectors and detection systems without developing/procuring entire Lidar system. LEE consists of pulse shaping electronics to drive independently the lasers for each echo and internal detection system to monitor the pulses. The short echoes can be in the range from 5 ns to hundreds of ns and the long echoes from 1 µs up to hundreds of µs. The repetition rates of the developed emulator are from 100 Hz to 10 kHz with limitation that the longest pulse does not exceed 10% of the duty cycle. The power difference between both echoes can be set and is as high as 60 dB. The dynamics of the echoes is better than 50 dB within the 8 ns in the rising/falling edge of the pulse (echo). The output power can be tuned by means of variable attenuators giving a range of the incoming echoes from -35 dBm to -100 dBm. The LEE can also emulate multiple returns with aforementioned dynamics.

A radiation hard image sensor HAS2 was chosen for the Juice Monitoring Camera, an important instrument to monitor the status of the JUpiter ICy moons Explorer (JUICE) spacecraft and to take wide-angle images of the Jovian system. To improve the perception, a radiation-hardened, non-organic color filter array (CFA) was deposited on the sensor silicon, with four colors: red, green, blue, and yellow. In this paper we present the results of the radiation tests on these customized image sensors. First, results on the total ionizing dose (TID) test up to 57 krad confirm that both the image sensor and the deposited CFA are resistant to gamma radiation in the measured range. Also, single event effects (SEE) measurements up to LET of 100 MeV•cm 2 /mg were performed. Three types of events were considered: single event latch-up (SEL), single event upset (SEU), and finally single event functional interruption (SEFI). Since only one SEL was registered on one of the samples at 62.5 MeV•cm 2 /mg there was no further analysis on this event. Based on the experimental results, the cross sections have been calculated for SEU and SEFI. These results were used as input for the SEE analysis with the CRÈME96 software. The rates of about 10 -4 and 10 -5 events/device/day were obtained for SEU and SEFI for quiet environment, respectively.

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Near-infrared, visible and ultraviolet (NIR-VIS-UV) lidar echo emulator (LEE) was developed to emulate the returns of a spatial lidar at three wavelengths (355 nm, 532 nm and 1064 nm) within the framework of the HOLDON project. It is used to characterize the detection chain formed by a HgCdTe avalanche photodiode (MCT APD), read-out integrated circuit (ROIC), and surrounding electronics, which will be used in a lidar remote sensing of earth's atmosphere. It emulates two echoes in the three wavelengths. A short echo (pulse width <10 ns) with optical power dynamic range between 0.2 nW and 200 nW and a long echo (pulse width of about 270 μs) in range from 0.1 pW to 25 pW. The long echo has two adjustable parameters which allow changing the shape of the pulse (from a ramp to a rectangular pulse). The combination of both echoes allows characterizing the detector over the full 60 dB dynamic range, the target for the detection chain. The system consists of only one laser diode at 1064 nm, a driver, and an arbitrary wave generator (AWG) as seed to create the three waveleghts. The second harmonic generation (SHG) technique was used to generate the beam at 532 nm from the 1064nm laser diode. In this case, a non-linear KTP crystal was used. The sum frequency generation (SFG) technique was used to generate the beam at 355 nm from both previous beams. For the SFG, two Periodic Poled Lithium Niobate (PPLN) crystals were used. To optimize the output at 355 nm the temperature of the PPLN crystals was controlled by means of Peltier elements. A LabView program was designed to control all the configuration parameters of both echoes (long and short) and the laser. The software controls also the optimal temperatures where the highest power is reached at 355 nm. The overall system was assembled as an elegant breadboard for easy transportation. The NIR-VIS-UV LEE offers all the necessary requirements for exhaustive characterization of the lidar detection chains at three wavelengths and high dynamic range.