Measurement of the Gaussian laser beam divergence - beam divergence

 2024-10-11 21:39:05

Wow! Either I'm buying more optics than I thought, or someone else is using the Internationally Recognized but universally unrecognized standard.As far as the MIL scratch/dig spec, Jean Bennet argued years ago that it was a purely cosmetic spec. If you use it that way, it works well. For instance, if I want laser optics, I spec 20/10, but if I only need commercial grade, I order 80/50. Condensers are 120/80, etc. Just for total confusion, I spec the scratch/dig on my pseudo-ISO prints as 5/80/50!-- Best regards,Steve Eckhardtskeckhardt at mmm dot com

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surface quality 60-40

I realise that the scratch number doesn't actually define the width ofscratches (like many people beleive) but references the samples usedfor comparison. According to the drawing C7641866 L, released in 1980, the mastersamples have moved from Frankford Arsenal to ARRADCOM. Can you stillget your samples calibrated against the masters as stipulated in Note6 of the drawing?If not how do all optics companies keep their scratch setscalibrated?Thanks.*-----------------------* Posted at: www.GroupSrv.com*-----------------------*

Information from OEOSC (who are developing a new standard due outearly next year) indicate that the old scratch dig comparisonstandard is carrying over to the new standard.

80 50 scratch-dig

> According to the drawing C7641866 L, released in 1980, the mastersamples have moved from Frankford Arsenal to ARRADCOM. Can you stillget your samples calibrated against the masters as stipulated in Note6 of the drawing?> > If not how do all optics companies keep their scratch setscalibrated?> >

"Additionally, the startling factor-of-10 change between Revisions Hand L has caused some users to speculate that the primary standardsmay have healed with the passage of time. Certainly the glass arounda scratch cannot flow (the viscosity of glass at room temperature iswell in excess of 10^15 Pa*s), but chemical weathering of the surfacedue to water vapor in the air is a possibility and could cause theprimary standard either to heal or to worsen. There is evidence,however, that most weathering would take place and stabilize within afew hours or days. In any case, a change has to be quite substantialbefore it is apparent to the naked eye and, I think, would be pickedup by the trained inspectors when they make repeated comparisons withsecondary standards. More probably, it seems to me, small scratchesthat are reported to have "disappeared" have been contaminated by thevolatile constituents of their wooden boxes and merely required a gooddegreasing,"Anyway it is the drawing that has changed with time, due to peoplesattempts to define the scratch number as a width. Revision H of thedrawing was the first define the scratch number as the width of thescratch in microns and also that calibration back to the masters isnot essential. However Revision H was quickly surperceeded two yearslater by Revision J which said the scratch width was one tenth thescratch number and all manufacturer generated standards must becalibrated against the master set. In any event nothing in thecertification procedure had changed, nor has it changed to this day. Remember that a certified set of submasters is boxed but nothermetically sealed and therefore it must be resubmitted periodicallyfor recertification - hence my question can you still get comparisonstandards certified against the masters?

This comes from the paper, "The Scratch Standard Is Only A CosmeticStandard" by Matt Young."Additionally, the startling factor-of-10 change between Revisions Hand L has caused some users to speculate that the primary standardsmay have healed with the passage of time. Certainly the glass arounda scratch cannot flow (the viscosity of glass at room temperature iswell in excess of 10^15 Pa*s), but chemical weathering of the surfacedue to water vapor in the air is a possibility and could cause theprimary standard either to heal or to worsen. There is evidence,however, that most weathering would take place and stabilize within afew hours or days. In any case, a change has to be quite substantialbefore it is apparent to the naked eye and, I think, would be pickedup by the trained inspectors when they make repeated comparisons withsecondary standards. More probably, it seems to me, small scratchesthat are reported to have "disappeared" have been contaminated by thevolatile constituents of their wooden boxes and merely required a gooddegreasing,"Anyway it is the drawing that has changed with time, due to peoplesattempts to define the scratch number as a width. Revision H of thedrawing was the first define the scratch number as the width of thescratch in microns and also that calibration back to the masters isnot essential. However Revision H was quickly surperceeded two yearslater by Revision J which said the scratch width was one tenth thescratch number and all manufacturer generated standards must becalibrated against the master set. In any event nothing in thecertification procedure had changed, nor has it changed to this day. Remember that a certified set of submasters is boxed but nothermetically sealed and therefore it must be resubmitted periodicallyfor recertification - hence my question can you still get comparisonstandards certified against the masters?

mil-prf-13830b pdf

Also, as I read the spec, the scratch number is very subjective and isa comparison to standard samples. However the dig number does relateto the actual width of the dig. The drawing I mentioned in my firstpost describes how to make the set of samples. This drawing has hadmany revisions that state many different things ie, "Scratch numbersdo not denote width of scratch. The numbers indicate that thescratch has the same weight or visual appearance as the masterscratch bearing the same weight number", "Scratch number denoteswidth of scratch in microns", "#10 Scratch = 1um +/- 0.1....", andthe ever popular "Dimensions are for reference only". Anyway as Iunderstand these dimensions on the drawing should be used as a guideto preparing your samples but they must be calibrated against themaster set.Perusing different websites and optics suppliers shows that everyonewants to link the scratch number to a width. Some go with the 10 =10 theory and some go with the 10 = 1. My original question on themaster samples was due to these two different schools of thought iecan anyone do the correct calibration or are companies just measuringthe width of their standard samples and saying they are calibrated? If it is the latter then the scratch criteria has changed to reflectMIL-F-48616 - which allows for the actual measurement of the width ofthe scratch but uses letters instead of numbers eg F-F.

Just for total confusion, I spec the scratch/dig on my pseudo-ISO prints as 5/80/50!-- Best regards,Steve Eckhardtskeckhardt at mmm dot com

mil-c-48497

iso 10110-7

As far as the MIL scratch/dig spec, Jean Bennet argued years ago that it was a purely cosmetic spec. If you use it that way, it works well. For instance, if I want laser optics, I spec 20/10, but if I only need commercial grade, I order 80/50. Condensers are 120/80, etc. Just for total confusion, I spec the scratch/dig on my pseudo-ISO prints as 5/80/50!-- Best regards,Steve Eckhardtskeckhardt at mmm dot com

If not how do all optics companies keep their scratch setscalibrated?Thanks.*-----------------------* Posted at: www.GroupSrv.com*-----------------------*

Information from OEOSC (who are developing a new standard due outearly next year) indicate that the old scratch dig comparisonstandard is carrying over to the new standard.

C7641866

Recently we've had some (Japanese) vendors insist on an ISO callout ratherthan the MIL standard for scratch and dig...We're told by our main lens vendor (China) that they're seeing 35-40% (andincreasing) ISO format drawings"gac" wrote in messagenews:416ccabf$1...@127.0.0.1...

iso 10110-7 pdf

mil-c-675

Information from OEOSC (who are developing a new standard due outearly next year) indicate that the old scratch dig comparisonstandard is carrying over to the new standard.

I would contend that this is the industry standard. It is true thatthis MIL spec keeps appearing but in my experience of manufacture ofhigh end optics this does not apply. I'm a little rusty about theactual methods used to apply this spec but doesn't it state that itshould be a visual comparison by eye to the scratch/dig standard undera 40 watt light in a darkened booth viewed at 45 degrees.If I was to inspect and pass optical surfaces in that manner I'd passeverything..... Oh wait what am I fighting it for !!??Taff

Anyway it is the drawing that has changed with time, due to peoplesattempts to define the scratch number as a width. Revision H of thedrawing was the first define the scratch number as the width of thescratch in microns and also that calibration back to the masters isnot essential. However Revision H was quickly surperceeded two yearslater by Revision J which said the scratch width was one tenth thescratch number and all manufacturer generated standards must becalibrated against the master set. In any event nothing in thecertification procedure had changed, nor has it changed to this day. Remember that a certified set of submasters is boxed but nothermetically sealed and therefore it must be resubmitted periodicallyfor recertification - hence my question can you still get comparisonstandards certified against the masters?

Perusing different websites and optics suppliers shows that everyonewants to link the scratch number to a width. Some go with the 10 =10 theory and some go with the 10 = 1. My original question on themaster samples was due to these two different schools of thought iecan anyone do the correct calibration or are companies just measuringthe width of their standard samples and saying they are calibrated? If it is the latter then the scratch criteria has changed to reflectMIL-F-48616 - which allows for the actual measurement of the width ofthe scratch but uses letters instead of numbers eg F-F.

From my understanding the inspection is, as you mentioned, with a 40Wlight bulb etc. Also, as I read the spec, the scratch number is very subjective and isa comparison to standard samples. However the dig number does relateto the actual width of the dig. The drawing I mentioned in my firstpost describes how to make the set of samples. This drawing has hadmany revisions that state many different things ie, "Scratch numbersdo not denote width of scratch. The numbers indicate that thescratch has the same weight or visual appearance as the masterscratch bearing the same weight number", "Scratch number denoteswidth of scratch in microns", "#10 Scratch = 1um +/- 0.1....", andthe ever popular "Dimensions are for reference only". Anyway as Iunderstand these dimensions on the drawing should be used as a guideto preparing your samples but they must be calibrated against themaster set.Perusing different websites and optics suppliers shows that everyonewants to link the scratch number to a width. Some go with the 10 =10 theory and some go with the 10 = 1. My original question on themaster samples was due to these two different schools of thought iecan anyone do the correct calibration or are companies just measuringthe width of their standard samples and saying they are calibrated? If it is the latter then the scratch criteria has changed to reflectMIL-F-48616 - which allows for the actual measurement of the width ofthe scratch but uses letters instead of numbers eg F-F.

According to the drawing C7641866 L, released in 1980, the mastersamples have moved from Frankford Arsenal to ARRADCOM. Can you stillget your samples calibrated against the masters as stipulated in Note6 of the drawing?If not how do all optics companies keep their scratch setscalibrated?Thanks.*-----------------------* Posted at: www.GroupSrv.com*-----------------------*

I have a question regarding the MIL spec that has become the industrystandard for specifying scratch-dig.I realise that the scratch number doesn't actually define the width ofscratches (like many people beleive) but references the samples usedfor comparison. According to the drawing C7641866 L, released in 1980, the mastersamples have moved from Frankford Arsenal to ARRADCOM. Can you stillget your samples calibrated against the masters as stipulated in Note6 of the drawing?If not how do all optics companies keep their scratch setscalibrated?Thanks.*-----------------------* Posted at: www.GroupSrv.com*-----------------------*