Strainoptics Laser GASP® or LCD GASP®
Quick-Start Guide
CAUTION: DO NOT LOOK DIRECTLY AT THE LASER LIGHT.
Placing a reticle line “very close” to the
edge of a fringe creates a sliver of light
between the two. This sliver of light
(negative space) is easily balanced for
uniformity along the entire edge of the
fringe. This will give the most consistent
indication of parallelism.
Placing a reticle directly
over the black fringe
does not give the best
indication of parallelism.
light intensity in the eyepiece or LCD monitor, slowly move the input head (“B”) backward or forward
until maximum light intensity is seen. Tighten the input head locking knob.
b. To optimize the laser light path –Slowly turn the input head tilt-adjust knob (“F”) while observing the
laser light exiting the cal-plate at the edge. Adjust the light path until it is as close to the top surface
of the cal-plate as possible, without losing light intensity.
c. While looking down into the eyepiece or observing the LCD monitor, slowly adjust the mirror pivot
lever (“G”) until a red laser light or alternating red and black lines (known as fringes) are visible. If
needed, slowly rotate the tilt-adjust knob (“F”) until the lines are well defined. If the image appears
cut off at either end, slowly slide the wedge compensator assembly (“H”) left or right to center the
image and maximize the viewing area.
4. MEASURING THE CAL-PLATE: Once a robust image of the cal-plate fringes is obtained, rotate the
protractor dial (“I”) until the reticle lines in the eyepiece are aligned parallel to the black fringe lines in the
image.
a. NOTE 1: The reticle lines do not have to be placed over the fringe lines. To ensure parallelism,
position the reticle lines slightly offset from the fringe lines and use the “negative space” between
the fringe line and the reticle lines to arrive at the proper position (refer to illustration below). Note
the angle of the protractor scale at the degree indicator (“J”).
b. NOTE 2: The fringes will slant to the left on the standard GASP, but will slant to the right on the
LCD-GASP or Auto-GASP to indicate compression.
5. ANGLE CONVERSION: To convert the angle reading to a stress value, use the angle vs. stress
table that came with your GASP. This conversion chart was designed specifically for your GASP
and is not interchangeable with any other instrument.
6. YOU’RE DONE! Now that you have obtained a fringe image of the cal-plate and successfully
measured its surface stress, you can repeat the steps above for your glass.
MEASURING YOUR GLASS: NOTE THAT YOUR GASP WILL ONLY WORK ON THE TIN SIDE OF
YOUR GLASS. TO VERIFY THAT YOU ARE MEASURING ON THE TIN SIDE OF THE GLASS, USE
THE UV LAMP THAT CAME WITH YOUR GASP (Strainoptics Part #UV-1301). To minimize the
possibility of damage to the Laser GASP’s prisms, be sure that the glass is free of abrasives.
If you are having difficulty using your GASP, please contact
be glad to help!
Reticle lines
(Choose one to work with)
Reticle not
parallel to fringe.
