Q. How sensitive is the measurement to device position with respect to the optical axis position 0,0?
If your device is off the true optical axis by 0.1 cm, it will cause a 0.68-degree pointing error. If your device is off the true optical axis by 0.01 cm, it will cause a 0.068-degree pointing error. A displacement of 0.025 cm will cause an angular width error of <0.1 degree.
Q. How sensitive is the device to datum distance?
Entering the correct value for the source aperture distances
is very important because an error of a 0.1 cm in this distance results in
approximately a 1% angular width error. This distance is input to the
instrument software as the Aperture-Source distance in cm units. This
distance affects the instrument's angular field of view; the larger this
distance the narrower the possible field of view for the device.
Q. My device points off the optical axis by a few degrees by design. How accurate is the measured angular width?
If you position the device on the optical axis 0,0 you will get good results using a full spherical measurement with at least 50 cuts and the centroid analysis. The more rapid XY orthogonal measurement mode will be somewhat in error because it assumes the beam centroid is coincident to the optical axis.
Q. Will Photon help with our mechanical designer's questions when we design our own mounting?
Yes. We want you to be successful using the instrument. Photon will provide
support to your design department. When you are ready to begin your design,
call for a copy of key chapters from the instrument manual. You may also
refer to the Application Note, Interfacing With the LD 8900.
Q. How do I know the unit is still in calibration?
Photon has NIST traceable calibration standards available to verify measurement accuracy. Call Photon for more details.
Q. I'm measuring a narrow beam, and I see a flare on the screen.
Blind spot correction in the software generates an artifact. We recommend that you turn off the blind spot correction. This artifact is mostly cosmetic. For the scans in which the blind spot occurs, it affects the data. For the full 3D measurement, the total power and centroid positions are not significantly affected.
