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Manual Mode 9.3
An optical rail assembly and a focusing element of a known focal length are required. ISO/DIS 11146-1 must
be used as the basis for your rail design. The focusing element must be an aberration-free mirror or a plano-
convex lens.
In the following example we have used a lens-based approach. The focusing element should be selected to
provide a smallest focused spot width of at least 10 camera pixels across. For a Pyrocam IV or IIIHR, the
focused spot must be at least 800μm. The rail must be long enough to allow the camera to translate at least 2
Rayleigh lengths on both sides of the waist region.
When using Manual Mode, the user is required to:

Change the camera position on the rail

Adjust the aim of the beam

Adjust the attenuation of the beam

Block the beam when prompted
 Determine whether to accept each data frame
 Accurately set the distance from the lens to the sensor inside the camera for each data point
Optical Rail Setup 9.3.1
The figure below depicts the general features of the optical rail arrangement. The rail must be parallel to the
incoming laser beam, the lens and camera must be at the same height on the rail, and the camera must be
able to slide along the rail. A two-mirror arrangement for aiming the beam along the rail is suggested.
Also, as shown in the figure above, it is often advisable to employ attenuation. The necessity for this
arrangement increases proportionally to the output energy/power of the laser.
While not shown in the image, a device that can completely block the laser beam from the camera is a
necessity. Each time the camera performs an Ultracal or Ultracal check, the beam must be completely shielded
from the camera sensor.
It is also a good idea to place a relatively large ND filter immediately in front of the camera. This filter is
helpful in blocking out ambient background light.
It is recommended that measurements be performed in a low light or a darkened room setting.