ScanImage 2018 : Optimization of Scanned Images Aspect Ratio
Optimizing image aspect ratios for X/Y scanner pairs requires correct settings for the angular range of each scanner.
These must be specified in the Machine Data File (MDF).
This guide provides information about:
- (left) the relevant MDF settings
- (right) typical MDF values for various market-available scanners
Machine Data File (MDF) Settings
The following key Machine Data File settings affect the image aspect ratio
%% ResScan Section
- %% LinScan Section
The Volts Per Optical Degree values specify the amount of control voltage required to drive each scanner to a specified angle deflection from the center
The Angular Range values specify the peak-to-peak angular range of each scanner
(of which a specified Fill Fraction is imaged, as configured within ScanImage)
These values are in optical degrees - which is 2x the mechanical angular range of the scanner, because of the laser reflection
Angular Ranges at Zoom=1
Zoom 1 is automatically defined as a square scan of the smaller of the two scanner angular ranges
BUT - it is permissible to use the full angular range of the larger of the two angular ranges, via the ROI/Stimulus Group Editor dialog
Typical MDF Settings
Sutter Res Scanner Systems
Typical Sutter resonant scanner system
|Resonant (X)||26 degrees||0.1923|
|Galvo (Y)||20 degrees||1.0|
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Cambridge Technologies OEM Resonant Scanners
|CRS-8 (new driver board)||26||0.1923|| |
|CRS-8 (old driver board)||15||0.33|| |
|CRS-12|| || || |
Cambridge Technologies OEM Galvo Scanners
The specifications for galvo scanners from Cambridge Technologies are listed on specific order sheets when purchased
Below are typical Angular Range & VoltsPerOpticalDegree values for standard X/Y scanner sizes and configurations
|3mm||Standard||60 degrees||0.33||Matched to smaller objective lenses (back focal aperture < 10mm). Typical for slice & fly applications.|
|5mm||Standard||40 degrees||0.5|| |
|5mm||Reduced Angle||20 degrees||1.0|| |
|6mm||Standard||40 degrees||0.5|| |
Cambridge has 2 types of X/Y scanner configurations
|Reduced Angle||X & Y scanners are the same size, achieving the best and most uniform speed. |
The tradeoff is somewhat reduced angular range for the scanner pair.
|Standard||Y scanner elongated compared to X scanner. |
This ensures full X scanner range is incident on Y scanner.