Posted in September 2010

If you are interested in camera calibration techniques using projective transformation, please have a look at the additional information in the "ScratchOptica AgoraCamera Calibration" directory.

On 29th September we will discuss a technique for the calibration of a pinhole camera.

To be prepared, please read the Paper "100929 – On Plane-Based Camera Calibration – A General Algorithm, Singularities, Applications" until the end of section 3 (that’s only 1.5 pages !). The paper can be found in the ScratchOptica Agora directory. In the beginning, I will give a short description of the camera model used in this paper.

We have decided on the future chairmans for the coming months at the Agora:

The Agora is open to everyone, and we recommend it to the Erasmus Mundus Students, the Master Students and the PhD students. Staff should also be present!

Jeff will present us this wednesday some of his work about piezo calibration.

Abstract:

VINCI was the first interferometric instrument used at the VLTI
astronomical interferometer. It performs single spatial mode interference
using an optical fiber combiner using stellar radiation in the astronomical
"K" band (2-2.4 microns). The fringe packet is scanned over its coherence
length using an external path controlled by a piezoelectric actuator.
Alternate scans are in opposite directions, each over a range of about 100
wavelengths. Although the stellar radiation has a much shorter coherence
length, many technical runs used a laser test source which is therefore
coherent over the entire range of each scan and at a specific wavelength,
and from this the motion of the piezo can be derived in detail.

I will present various results concerning the piezo motion derived in this
manner. In addition to an overall error in its velocity compared to its
nominal value, the results display a linear change in the velocity over the
range of the scan (thus a parabolic error in phase), and also a "kink" in
its motion. These effects are distinct between scans in the up and down
directions. In addition to these results concerning the VINCI piezo
actuator, I will present similar conclusions in regard to the piezo
actuator used in the interferometric experiment currently setup to
demonstrate the NOVA Fringe Tracker (NFT) concept using a He-Ne laser.
Further discussion of the characteristics of piezo actuators, widely used
in such interferometric applications, is invited.

On 15th
September we will continue our current topic with an example of self
calibration of divided circles. We will discuss the paper "100915 –
Self-calibration of divided circles on the basis of a prime factor
algorithm.pdf". To be prepared, please read the mentioned paper until the end of section 2. The paper can
be found in the ScratchOptica Agora directory.

The Topic for the Agora meeting on 8th September will be "Self-calibration of a white light microscope". To be prepared, please read the paper "100908 – Self-calibration of a scanning white light interference microscope.pdf" located in the ScratchOptica Agora directory.

 Also, since once a month food is offered to all the group members that can attend the event, during this session it will be offered to the partecipants. Please put your name on the following link as soon as possible, in order to allow us to order the right amount of food:

 http://www.doodle.com/92btf2hws6c5gcrd 

 Hope to see all of you there.

The next agora, of the 1st of September, will be chaired by Axel. The topic is "Self-calibration and absolute measurement". Please find in the scratch the paper related to this topic.