PMID- 28430222
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20180205
LR  - 20181023
IS  - 1539-4522 (Electronic)
IS  - 1559-128X (Linking)
VI  - 56
IP  - 12
DP  - 2017 Apr 20
TI  - Impact of partial coherence on the apparent optical transfer function derived 
      from the response to amplitude edges.
PG  - 3518-3530
LID - 10.1364/AO.56.003518 [doi]
AB  - We present an investigation of the impact of partial coherence on optical imaging 
      systems with the focus on whole slide imaging (WSI) systems for digital 
      pathology. The investigation is based on the analysis of the edge response of the 
      optical system, which gives rise to an apparent optical transfer function (OTF) 
      that can be linked to two elementary complex functions Q and U. The function Q is 
      directly related to the transmission cross coefficient (TCC) and can be 
      identified with the performance function first introduced by Kintner and 
      Sillitto. The function U depends on the TCC in a more involved way. When there 
      are no aberrations the Q-function corresponds to the real part of the apparent 
      OTF and the U function to the imaginary part of the apparent OTF. Close to the 
      incoherent limit the effect of the U function is a mere shift of the edge 
      compared to the fully incoherent case. We propose a new expression for the 
      dependence of the depth of focus (DOF) on spatial frequency and on the partial 
      coherence factor sigma, and validate it by simulation. Partial coherence effects are 
      investigated experimentally on a WSI system with a compact LED-based Kohler 
      illumination unit with variable condenser NA. This unit incorporates a top hat 
      diffuser for providing a reasonably uniform illumination field, with variations 
      below 10% across the imaged field of view. The measurements of the apparent 
      through-focus OTF derived from edges on a custom resolution chart for different sigma 
      were substantially in agreement with the simulations. Finding an optimal value 
      for sigma is not straightforward as lateral resolution and the level of edge ringing 
      improve with increasing sigma, whereas edge contrast and DOF improve with decreasing 
      sigma. We assess that the trade-off for the particular application of WSI systems for 
      digital pathology is optimized for a sigma value in the range of 0.55-0.75.
FAU - Mojtaba Shakeri, S
AU  - Mojtaba Shakeri S
FAU - van Vliet, Lucas J
AU  - van Vliet LJ
FAU - Stallinga, Sjoerd
AU  - Stallinga S
LA  - eng
PT  - Journal Article
PL  - United States
TA  - Appl Opt
JT  - Applied optics
JID - 0247660
EDAT- 2017/04/22 06:00
MHDA- 2017/04/22 06:01
CRDT- 2017/04/22 06:00
PHST- 2017/04/22 06:00 [entrez]
PHST- 2017/04/22 06:00 [pubmed]
PHST- 2017/04/22 06:01 [medline]
AID - 363059 [pii]
AID - 10.1364/AO.56.003518 [doi]
PST - ppublish
SO  - Appl Opt. 2017 Apr 20;56(12):3518-3530. doi: 10.1364/AO.56.003518.