Point Source Microscope
PSM Point Source Microscope for Optical Alignment
EASY SYSTEM ALIGNMENT
OTHER OPTICAL METROLOGY USES
Picture of PSM aligning an off-axis parabola to a fiber feed using a plane mirror
In addition to its use for alignment, the PSM is useful for incoming inspection for radius of curvature, focal length, figure errors larger than 8th wave and centering errors.
The small beam size makes it particularly useful for small prisms.
Note on using PSM with other light sources
We are often asked if the PSM can be used at wavelengths other than the standard internal laser diode and LED sources at 635 nm. The answer is definitely yes by coupling in an external fiber feed light source.
The PSM performs to original specifications all the way from 405 to 1080 nm without any modification.
This makes the PSM useful for aligning laser diode sources to other components in an optical system, for example. The useful spectral range for the PSM may be even greater, we simply have not tried over an even broader range.
A COMPLETE, SELF-CONTAINED, PORTABLE METROLOGY SYSTEM
Full field video microscope images and point source Star images can be saved in png format for later analysis and use.
Think of the PSM as a Swiss Army Knife for your Lab
Scroll down to bottom for a bibliography of archival PSM papers.
FAQ: Can the wavelength of the laser diode source in the PSM be changed from the standard wavelength of 635 nm?
Yes, the PSM comes with an internal source whose wavelength is 635 nm which is fiber coupled into the PSM via a FC/APC fiber connector. The internal source fiber can be unscrewed and stored in an adjacent storage fiber connector. An external source is then coupled into the now vacant active FC fiber connector. The external source fiber to the PSM must be terminated with a FC/APC connector for the PSM to work properly.
The beamsplitters in the PSM have broadband coatings so any source from 350 to 700 nm can be used and even beyond with some loss in sensitivity. The Thorlabs S1FCxxx fiber-coupled lasers sources are well suited as are similar sources from qphotonics that provide a wider range of wavelengths. Incandescent sources can be coupled in as well as long as the termination into the PSM is a FC/APC connector. The losses will be large getting the white light in but the PSM is quite sensitive to low light levels.
FAQ: How is the spatial scale calibrated in the PSM?
The spatial scale in the PSM is controlled using the “Calibration Factor” on the Cal Tab. For a 10x objective the Calibration Factor should be about 1.0 and then the units displayed on the right hand side of the PSM2 GUI under Spot will be correct in μm. For a 4x objective the Calibration Factor should be about 2.5.
Many things influence the precise PSM calibration including the pixel size in the camera and the make of the objective lens. For precise calibration of the spatial scale it is best to use a sample of known line width such as a stage micrometer or Ronchi ruling and measure the width using as much of the field of view of the objective as possible.
Use the arrow cursor to click on one edge of the line and then click on the other edge. Green crosses will appear with each click. On the Threshold tab the coordinates of the green crosses are listed. If the distance between the two crosses at either edge of the known line is not correct, change the Calibration Factor by the ratio of the measured value to the known value and repeat the measurement. One or two times making the measurement should get to 1% of the true spatial scale. Note that the coordinates of each cross is with respect to the reference cross.
Once this is done the scales is correct for all readings on the GUI unless the objective or camera are changed in which case the calibration must be repeated. The units on the scale bar and the crosshairs are also controlled by this calibration and will be correct once calibrated. Notice the scale bar at the bottom of the Cal tab. It can be made any length, have any number of divisions and be placed anywhere on the video screen.
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