Title: Measurement data for "Off-Axis, slit based MTF measurements at PTB"
Authors: Schake, Markus, Physikalisch-Technische Bundesanstalt (PTB), Fachbereich 4.2 Bild- und Wellenoptik, ORCID: 0000-0002-9883-3494
Contributors: HostingInstitution: Physikalisch-Technische Bundesanstalt (PTB), ISNI: 0000 0001 2186 1887
Resource Type: Dataset / Measurement Data
Publisher: Physikalisch-Technische Bundesanstalt (PTB)
Rights: https://creativecommons.org/licenses/by/4.0/
CC-BY 4.0 International
Relationships: IsCitedBy: DOI 10.1117/12.3005522
Dates: Available: 2022-12-19
Classifications: OCIS 110.4100 Modulation transfer function ; OCIS 040.1490 Cameras ; OCIS 120.4800 Optical standards and testing ; OCIS 220.3630 Lenses
File: Download File (application/zip) 1.08 GB (1157421924 Bytes)
MD5 Checksum: f244799adabd296019e7a5813aee10f5
SHA256 Checksum: b8ef6ead74363fe54f80cf999451744edc6f8573b8d9a49487bc5d8b58c6f0fa
Keywords optical transfer function ; line spread function ; off-axis measurement ; cameras
Abstract: The provided data enable the immediate replication of the results presented in "Off-Axis, slit based MTF measurements at PTB."
The research data are structured with respect to the figures presented in the proceeding. The subfolder "MTF_Fieldscan_measurement_data_pm20_deg_pm40um_10repetitions" contains all necessary measurement data to receive the figure from the contribution by running a MATLAB file.
Therefore, it is possible to compare the results with full context to those presented in the contribution.
The measurement data saved as *.mat files contain the mean over multiple pixel rows of the line spread function (LSF) as recorded by the camera detector and the associated modulation transfer function (MTF) which is calculated as described in the conference proceeding.
The specimen under test is a calibration objective manufactured by Zeiss with infinite to finite imaging, a focus distance of f_s = 50mm and an f-number a_s = 4.
The following abbreviations are employed in the labeling of the subfolders:
pm -> Plus/Minus
deg -> degree
um -> micrometer
Other: We want to acknowledge the support of this project by Trioptics GmbH (Strandbaddamm 6, 22880 Wedel, Germany).
Remark: description of the individual files:
The subfolder "MTF_Fieldscan_measurement_data_pm20_deg_pm40um_10repetitions" contains N=10 repetition measurements of a field scan measurement in the rage of pm 20 deg in 1 deg increments (I=41).
At each angle a focus scan in the range of pm 40 µm around the focus point was performed in 4 µm steps (M=21).
The result of each focus scan is saved in a separate *.mat file.
Therefore a total of N*I=410 focus scans are recorded.

The data are saved in a python dictionary style. Each *.mat file contains the following fields:

baslermtf -> This contains a 3x2048x5x21 Matrix with the uninterpolated frequency axis, the MTF result and the LSF result.
- The first row of this matrix baslermtf(1,:,:,:) contains the uninterpolated frequency axis based on the ROI of 2048 pixels
This entry is the same for all repetition measurements and all field and focus positions, since it depends on the ROI and effective pixel size.
- The second row of this matrix baslermtf(2,:,:,:) contains the uninterpolated MTF results associated with the frequencies in baslermtf(1,:,:,:).
There are 2048 discrete frequency components due to the ROI was 2048 pixels before Fourier transformation.
At each position 5 MTFs were recorded, which have not been averaged here.
Each focus scan comprises M=21 positions, for which the recorded MTFs are different.
- The third row of this matrix baslermtf(3,:,:,:) contains the uninterpolated LSF results associated with the ROI of 2048 pixels.
These LSFs have been averaged along the vertical extend of the slit as described in the article.
At each position 5 LSFs were recorded, which have not been averaged here.
Each focus scan comprises M=21 positions, for which the recorded LSFs are different.
The recorded LSFs may be employed to calculate the MTFs as described in the article and control the results.
binning -> The pixel binning factor applied in the camera
camera -> The name of the camera device
exptime -> The employed exposure time
FCP_frequency -> The selected evaluation frequency in lp/mm before interpolation of the MTF data
image_stats -> Auxiliary information about the highest and lowest pixel intensity
loopID_fieldscan -> Identifier of the field scan repetition n=1,...,N for N repetitions
loopID_focusscan -> Identifier of the focus scan repetition (This is 1 for the measurement)
magnification -> The applied microscope magnification
measurement_ID -> Unambiguous measurement identifier
rot_axispos -> Position of the rotation axis 1xM
timestamp_init -> Timestamp of the measurement
x_axispos -> Position of the focus-axis 1xM (In the article this is referred to as z-axis for convenience of common notations)
y_axispos -> Position of the parallel field-axis 1xM (In the article this is referred to as x-axis for convenience of common notations)
z_axispos -> Position of the vertical field-axis 1xM (In the article this is referred to as y-axis for convenience of common notations, this position was fixed during the measurement)
Funding: Trioptics GmbH, ISNI: 0000 0004 9346 2828, Grant Title: MTF-Referenzmesstechnik