The Ariel User Manual
Rev 5, 01/04/21
10
Chapter 5: Pulsed Power
5.1: Physical Principle
The core of the Ariel is a high power copper thermopile disk that can measure short exposures of high
power lasers.
An internal, un-calibrated silicon photodiode detects the backscattered light to measure the exposure time.
Average power is then calculated by,
𝑃 =
𝐸
∆𝑡
,
where
P
is power,
E
is energy, and
Δt
is the time interval.
5.2: Limitations
The photodiode's sensitivity depends on wavelength, meaning that the minimum power that may be
detected by it also depends on the wavelength. The photodiode is not sensitive beyond 1100nm. Please
check the specifications for details.
2.94µm and 10.6µm lasers are not supported by the photodiode.
5.3: Display
The calculated power will be displayed in large digits. The energy will be
displayed in small digits on the left side, and the pulse width will be displayed
in small digits on the right side of the screen.
On
the pulsed power screen, a blinking 'RDY' message (meaning “READY”)
will appear on the top right corner to indicate that the Ariel is ready to
measure a pulse.
5.4: Errors
Situation
Device displays
Log note
No trigger detected
0
No trigger!
Pulse is too long
OVER
Pulse too long!
Pulse is too short
UNDER
Pulse too short!
Table 3: Pulsewidth errors
In a situation where the pulse width is not detected but the energy is measured, the device will display the
energy but not the calculated peak power. The peak power can be calculated manually if the pulse width
is known, using the equation above.
Figure 9: Pulse screen
