Whatever happened to the GaugeMaster, and what are we using to replace it??

[D.J. Roff, ABOM]

Hi, folks.... I'm just old-school enough to remember the quality inspectors at Pearle, going from shop to shop with their little tool-kits in tow. And in every one of those tool-kits was an indispensable tool called a Gaugemaster. I believe it was made by Younger, and it was a calibration tool for the lensometer. There were lenses in +/-6.00 and +/- 12.00, a 180-scored lens with cylinder, etc. This little device was used to make sure the lensometer was dead-on accurate, before the inspector made any judgement calls on the work.

Lensometers are not something you have to fool with every day, but I recently began work at an office which had a unit in poor repair... the optics needed to be disassembled and cleaned, and once reassembled, everything needed calibration. I called our lab to borrow their GaugeMaster, and discovered that they were jealously guarding their only one, because nobody is making them anymore! Luckily, they trusted me enough to loan it out for a day or two, but they wanted it back immediately.

Now, you can't tell me that nobody is ever going to need their lensometer calibrated, ever again. So my question is... what are we using to replace the dear old GaugeMaster? Or, alternatively, if someone has a motherlode of them for sale, please speak up!

D

[Steve Machol]

Yep, it was the Younger Gaugemaster. We always had one and used it regularly.

[optical24/7]

When I ran labs I made my own out of glass lenses. I verified the exact power on two vertometers that were Gaugemastered. I've jealously guarded mine also for almost 30 years. You could do the same with a trusted glass lab. Good luck D.J.

[vcom]

I always used lenses from the OD's trial frame set.

[MakeOptics]

$500 you can get mine, wooden box and manual included.

[Jacqui]

When I ran labs I made my own out of glass lenses. I verified the exact power on two vertometers that were Gaugemastered. I've jealously guarded mine also for almost 30 years. You could do the same with a trusted glass lab. Good luck D.J.

I did the same thing when I worked at AO in the late 60's. They still work. Made from wonderful, optically superior glass.

[rbaker]

I do believe that I have two Guagemasters in my Optical Archives (storage locker.) I will dig them out and put them up on Ebay.

[Roy R. Ferguson]

When we started administering the hands-on practical my company developed, GaugeMasters were provided the candidates at the test site to allow them to check the accuracy of their lens clocks and thickness gauges. We discontinued this practice after two problems cropped up. The first concerned the candidates asking proctors what the device was and requesting instructions on usage. Second, the instruments started walking away from the test site.

Roy

[Barry Santini]

The MOST important things users of manual lensmeters can do does NOT require a gaugemaster:

1. Set the power drum to PLANO (0.00D) precisely, and then rack out the eyepiece and focus in to clear the "TARGET", NOT the reticle! This compensates for both eye AND lensmeter power drum error.
2. Take a higher-power cyl lens (>2.00D), set both the axis dial AND the reticle to 180. Rotate and center the lens, carefully aligning the axis of the lens and centering the target. Mark the lens with the marker
3. Take the lens out, rotate it 180 degrees, and repeat #2
4. The error you see in centering (dot overlap/displacment) reveals TWICE the marker error in centering. Normal tolerance is 0.5mm marker dot diameter
5. The mis-match of the axis lines is also TWICE the MARKER error.

Repeat and re-align marker until fixed.

The only thing you cannot tell with the above is whether the axis wheel is aligned to the frame table. After calibrating the lens alone, try a mounted pair of high cyls in an appropriate frame. Mark both lenses at the appropriate axis for each, turn the frame upside down, and remark. Any axis mis-match between frame table and marker is then revealed.



As far as power calibration goes for high rXs, you really should be also using a good auto lensmeter with abbe toggle to check powers.

FWIW

B

[MikeAurelius]

^^ what Barry said.

Additionally, if you have access to a digital lensometer, verify a couple of +/- lenses with it, then use those verified lenses to calibrate the manual unit. Good luck.

[Barry Santini]

^^ what Barry said.

Additionally, if you have access to a digital lensometer, verify a couple of +/- lenses with it, then use those verified lenses to calibrate the manual unit. Good luck.

What Mike said!

B

[Roy R. Ferguson]

The following is for the Reichert ML1. Marco and B&L use similarsteps when focusing the eyepiece. With the piece of paper we are simulating Kohler Illumination or more commonly known as Bright Field Illumination with the "specimen" being the eyepiece reticle.

1. Place a white sheet of paper at the position of the lens stop. This will provide enough light to illuminate the reticle in the eyepiece.
2. Turn the eyepiece counterclockwise to the stop.
3. With both eyes open, look through the eyepiece with your dominant eye. Slowly turn the eyepiece clockwise until the black reticle lines are in sharp focus. Do not go beyond that point.
4. Remove the paper and press the ON/OFF switch. The pilot light will illuminate and the internal LED will turn on.
5. Turn the power wheel until the illuminated crossline target becomes clear.

I hope this helps.

Roy

[Barry Santini]

Focusing the reticle ONLY compensates for operator eye error...not power calibration. Who cares if the prism reticle is softly focused?

This is a VERY under appreciated aspect of manual lensometry. Whether one or more operators, we are ONLY interested in accurate readings, using the method I described , power accuracy is more completely ensured.

B

[Roy R. Ferguson]

Interesting point! You need to share this with Reichert, Marco, and B&L.

Roy

Focusing the reticle ONLY compensates for operator eye error...not power calibration. Who cares if the prism reticle is softly focused?

This is a VERY under appreciated aspect of manual lensometry. Whether one or more operators, we are ONLY interested in accurate readings, using the method I described , power accuracy is more completely ensured.

B

[MakeOptics]

Focusing the reticle ONLY compensates for operator eye error...not power calibration. Who cares if the prism reticle is softly focused?

This is a VERY under appreciated aspect of manual lensometry. Whether one or more operators, we are ONLY interested in accurate readings, using the method I described , power accuracy is more completely ensured.

B

For lensometers with power readings on the drum, you often can unscrew the pointer and get enough play to remove up to +-0.25, Barry your method of leaving the reticule out of focus could cause the operator to accommodate slightly. Also it means that the telescope which the top component literally is no longer has parallel rays emerging from the eyepiece so your distance from the eyepiece would have to remain consistent in order to reduce the slight amount of error from stimulated accommodation due to the emerging vergence.

I have heard you mention this method before and no matter how I do the math the potential for error exists. It sounds like a unique trick that may apply to your particular way of reading a lens. Your results may be super accurate, but I would be concerned with the results being repeatable and reliable by others. As a teacher and lecturer refrain from teaching this method if possible to avoid others increases error in their readings.

This is a case of use the classic method.

See images below for documentation.

[Barry Santini]

Disagree make optics. As long as the same care is taken with focusing the target as is traditionally done with the reticle, their should be no accommodative error for that operator's eye.

in Optics by Oogle, there is a chapter on nodal slides, which is how a lens meter translates linear differences into power readings. Their is no difference between my system and the traditional method in terms of using the eyepiece to compensate for operator eye error. We are just using it to tweak the lensmeyer's nodal slide as well.
B

[MakeOptics]

Disagree make optics. As long as the same care is taken with focusing the target as is traditionally done with the reticle, their should be no accommodative error for that operator's eye.

in Optics by Oogle, there is a chapter on nodal slides, which is how a lens meter translates linear differences into power readings. Their is no difference between my system and the traditional method in terms of using the eyepiece to compensate for operator eye error. We are just using it to tweak the lensmeyer's nodal slide as well.
B

The accomadation can come from trying to focus in on the reticule as well as the target mires. More an issue for the young techs in the office then the old timers. ; )

Barry you know that careful adjustment of the stop can make this entire conversation moot, or even an adjustment of the set screw on the side can allow enough play to correctly align the pointer to the accurate power on the power drum. Even the power drum has set screws that will allow a little play to adjust the power.

I can't say I have ever read Optics by Oogle or even heard of it, I'll check it out.

[Fezz]

Make optics,

Check Abe Books. They have a few copies if the correct title is:

OPTICS; an introduction for ophthalmologist

[MakeOptics]

Here are some nice video resources:

John is straightforward in his instruction and I appreciate not going into the details on this type of instructional video it leaves room for further instruction when training staff.



Dr Suzanne Vassallo has a great series that you can find at the internet archives, very nice videos but a few little mistakes that are present in the videos which must be addressed but overall quality is great.

[RichV]

Hi all.
I'm new to the site, but not the industry. I've recently been told that gauge masters need to be re calibrated every 3-5 years. Never have I heard of such a thing. Has anyone?

[Robert Martellaro]

Hi all.
I'm new to the site, but not the industry. I've recently been told that gauge masters need to be re calibrated every 3-5 years. Never have I heard of such a thing. Has anyone?

Hi Rich, welcome to OB.

They are used to calibrate lensometers. The lenses that are used are certified accurate. The AO lenses in the picture below were certified by the National Bureau of Standards (now called the National Institute of Standards and Technology).

Maybe they meant that the lensometers need to be calibrated every three years.

[RichV]

Hi Rich, welcome to OB.

They are used to calibrate lensometers. The lenses that are used are certified accurate. The AO lenses in the picture below were certified by the National Bureau of Standards (now called the National Institute of Standards and Technology).

Maybe they meant that the lensometers need to be calibrated every three years.

Thanks Robert and thanks for the reply. I know what the gauge master is for. Just wanted to make sure there wasn't something I've never heard of. The reason I ask such an odd question is because my corporate "powers that be" have told all the stores that have a gauge master to send them back to corporate headquarters because they are "devising a company wide uniform lensometer calibration procedure" and they are collecting all the gauge masters to "ensure their accuracy and re-calibrate if necessary."

Gotta love these corporate execs. Devising and implementing programs on subjects they clearly know little to nothing about.

[MikeAurelius]

Thanks Robert and thanks for the reply. I know what the gauge master is for. Just wanted to make sure there wasn't something I've never heard of. The reason I ask such an odd question is because my corporate "powers that be" have told all the stores that have a gauge master to send them back to corporate headquarters because they are "devising a company wide uniform lensometer calibration procedure" and they are collecting all the gauge masters to "ensure their accuracy and re-calibrate if necessary."

Gotta love these corporate execs. Devising and implementing programs on subjects they clearly know little to nothing about.

Oy. I wouldn't do that, but then again, I am considered somewhat of a rebel to authority.

[RichV]

Oy. I wouldn't do that, but then again, I am considered somewhat of a rebel to authority.

I'll usually do what I'm told while I voice my opposition. Usually 6 months or so later I end up telling them "See? Told ya so."

[Barry Santini]

For manual lensmeters, for the 90% of the Rx range, you can simply calibrate power by NOT focussing the reticle, but rather the mire with the power drum set at PLANO (0.00). SEE ABOVE. for marking accuracy, take a stronger powered lens , >5D, mark it up, then turn it over, recenter and remark. The difference between the markings must be less than 0.5mm. Or adjust the marker. For axis, things get a little more complicated, but try the centering method above. The difference between the lines in degrees represent twice the error is the marker.

B