Power Density calculator of laser scanning device

The standard performance measurement of illuminating a specimen on a microscope is measuring power density in mW/mm² or mW/cm² at the specimen plane. If the specimen area is illuminated evenly, it possible to ignore laser beam shape altogether, and just calculate power density as:

However, with small laser scanned regions, the laser Gaussian beam shape creates edge artifacts or delivers lower power in a circular distribution. This script was written for this possibility. Below is the output for laser illuminating a 14 x 14 pixel region of interest (ROI)

Example Output

>>> 
Running script: u'C:\Documents and Settings\p.nanda\My Documents\GitHub\microscope-optical-input\raster.py'
Laser Beam at Back Focal Plane-
Measured Power:   5 uW

Laser Beam at Objective Specimen Plane-
Calculated Power:   3 uW
Measured Width: 0.8 um, in FWHM

Beam Profile Pixelation at Back Focal Plane-
Calibration: 0.212 um/pixel
Size: 10 x 10 pixels, covering 3 standard deviations
<Plotting power of beam profile>

Region of Interest-
Drawn Size: 14 x 14 pixels or 2.96 x 2.96 um
Drawn Area: 8.78 um^2
...but due to edge spill over from laser raster scan...
Actual Size: 24 x 24 pixels or 5.08 x 5.08 um, to 3 standard deviations
Actual Area: 25.80 um^2, to 3 standard deviations

Power at Objective Specimen Plane-
Average Power: 66.7 W/mm^2 over Drawn Area
<Plotting power around ROI>

Energy at Objective Specimen Plane-
Dwell time: 80 us
Repeats: 1
Average Energy: 5.3 J/mm^2 over Drawn Area

<Plotting center cross section across ROI>

<Saving power around ROI to file>
>>> 

Usage

These sets of variables need to be hand edited in the Python script:

Measurements:

• Ps power source - measurement of the optical input laser beam at the microscope nose piece without the objective
• Wo_FWHM optical input laser beam size measured at specimen plane using a uniform fluorescent ethidium bromide slide

Experimental parameters:

• mag_objective
• w ROI pixel width
• h ROI pixel height
• dwell_time laser beam parameter
• repeats laser beam parameter

Optical Specifications:

• To percent transmission of laser wavelength by objective
• camera_pixel
• mag_camera_tube_lens