A scheme of the measurement setup is shown in
Figure 1. The egg is candled with a halogen lamp
(230 V/35 W and color temperature: 2,800 K) and
the transmitted light is collected by a hyperspectral camera (PFD V10E manufactured by SPECIM) within the spectral range from 400 nm to 1,000 nm. Up to
10 eggs can be analyzed simultaneously within the camera’s
field of view. Extraneous light would mask the
important signal. Therefore, the measurement setup requires
a dark environment, which is ensured by a lightproof
case.
Halogen lamps produce significant amounts of heat
that might have a negative impact to the embryo if the
candling time is too long. We used illumination only
during image acquisition (max. 500 ms) and we have
observed no negative effects on the developing embryo.
The camera provides a spectral sampling of
0.78 nm/pixel without binning of sensor elements. With
binning, it is possible to collect the charge of 2, 4, or
8 pixels in spatial and/or spectral dimension. For constant
exposure time, binning increases signal amplitude,
but reduces the spatial and/or spectral resolution. We
decided to use a spectral binning of 2 and a spatial binning
of 8. To get a signal with sufficient amplitude but
without saturation, an exposure time between 250 ms
and 500 ms was used, depending on the age of the embryo
(Table 1).
Figure 2 shows a frame acquired by the camera for
10 eggs. Each column of the frame represents the spectral
profile of a spatial position in line scan. The example
of a single spectrum shows that the incubated egg