eusoballoon optics characterisation

Camille Catalano and the Toulouse team

Test configuration

Calibration of the beam

Exploration of the focal plan

1 - Configuration of the optics tests

Typical light source : 390nm LED1m collimator to create a parallel light beamTypical Incident angle of 3.5°CCD camera + NIST calibrated photodiode used at the focal planThe optics system is composed from only two fresnel lenses

2 - Calibration of the collimated beam

Scan of the entire beam, calibrated in light power

-> 80494±4370 nW (~5% error)

Calibration of the beam :

Grid pattern placed on the aperture of the instrument~160 measurements with the NIST

Visualisation of the beam with azurins in white paper on the aperture of the instrument

-> the photo of the white screen is comparable with the NIST measurements

• from the NIST mapping of the beam

• from the photo of the white paper on the aperture

2 - Calibration of the collimated beam

3 - Exploration of the focal plan

Method : Measurement of the light flux with the NIST along an axis perpendicular with the optical axis

Approximation of the encircle energy with the calculation at each position of the integrated flux on a ring of 1cm of thickness (size of the nist = 1cm^2). The integrated flux is then summed with those from the inner rings.

•Method to approximate the encircle energy

collimatorCollimated light beam

Optical system

NIST measurements along perpendicular axis

3 – Exploration of the focal plan

Encircle energy with the NIST :

eopt = 30.5±3 %

Efficiency :(defined as the fraction of the flux collected in the cm2 centered on the focal spot)

Full Width at Half Maximum = ~8mm

• Scan of the focal plan with the NIST.Blue = direct measurement of the NISTRed = encircle flux

λ=391nmθ=3.5° off axis

Encircled energy

In the central cm2 :eopt = 30.5 %

In ~3x3 PDM pixels :eopt = 24 %

eusoballoon optics simulation for data analysis

Camille Catalano

Simulation for data analysis

Modeled real object (forest,

flasher,…)

Simulated data

Real data

Simulation of the whole instrument

Simulation for data analysis

Problem : simulation programs didn’t simulate all the diffuse light measured during the optics characterisation

Simulation made with ZEMAX

Simulation for data analysis

A solution :

Add artificial scattering on optical surfaces in order to truly reproduce the experimental data

Then introduce those changes in the whole instrument simulation

My ZEMAX study of artificial scattering in progress…