Planning Stage

H. Li et al, Improving the precision of fluorescence lifetime measurement using a streak camera, Chinese Optics Letters 8(10),934-936 (2010).

An etalon of known timing separation is used to calibrate the time axis of a streak camera. The time axis is fit accordingly to a 4th-order polynomial equation. This performs the same method of fitting non-linearity on the time axis and non-uniformity of pixel gain, but without assuming a sinusoidal pattern. The technique is for a one-time calibration of the time axis that can be applied for all future data, versus our real-time method. The field non-linearity is much less pronounced in their system compared to ours, where the sinusoidal sweep amplitude is at the edge of what can fit on the readout screen. This calibration method was successful in reducing the error in a fluorescence lifetime measurement (Rose Bengal, 700ps) from 10% to 2%.

Similarities:

• use of defined time separations to map the temporal nonlinearity
• calibration factors for time as well as collection time (“gain non-uniformity”)

Differences:

• 4th order polynomial fitting versus sinusoidal fit
• not a real-time approach, not suitable for drift conditions

W. Uhring et al, Very high long-term stability synchroscan streak camera”, Review of Scientific Instruments 74 (5), 2646-2653 (2003).

This paper directly targets the drift sources in an Optronis streak camera. Patrick Summ of Optronis is listed as a co-author, though the paper is written by Groupe d'optique appliquée PHASE of the Centre national de la recherche scientifique (CNRS) in France. A two-pronged approach is taken. First, the sweep voltage is observed by either inductive or capactive coupling, and corrected using a phase-locked loop. This achieves higher stability, but does not account for drift factors that are not associated with the sweep voltage - for instance, the high voltage photocathode. It is for this reason that they employ a laser reference spot, to correct for the final result instead of a major contributing factor. This system applies a real-time correction of phase by following and correcting a laser spot on the screen. Only one reference spot is provided, so this does not provide any form of linearity correction.

Similarities:

• real-time correction of drift
• same basic method of correcting the COG of a reference spot on screen

Differences:

• single spot used to fix drift, with no extension to time axis correction