Broken Scanner Mirror

[pschlosser]

Finding a replacement mirror the exact dimensions of the broken one is proving to be more challenging than I originally thought. The mirror I broke on my DT-40W was the larger of the two, measuring 5mm x 16mm x 0.8mm.

One Stop Laser Shop offered some “universal replacement” mirrors measuring:
6mm x 11mm x .7mm mirror is $24.95 per mirror plus $5.85 shipping.
7.5mm x 13mm x .7mm mirror is $35.95 per mirror plus $5.85 shipping.

Jian of DT Electronics China offered:
9mm x 16mm x .8mm mirror for $9.00 + $35 shipping.

While the DT mirror is the most promising, since it seems to be at the length (16mm) the wide-angle DT-40W’s may need, it’s nearly twice as wide (9mm), suggesting to me it weighs close to twice as much as the original mirror. I’m concerned there will be a negative impact on performance using a mirror with twice the mass as the original.

I’m willing to pay DT’s steep shipping fees if it were a more precise replacement. Paying $35 to ship something that weighs about a gram is painful.

I see now why some people cut their own mirrors. At times like these, few things in life seem simple.

If I am to cut my own, where do I begin looking for raw materials to work with?

[dsli_jon]

Good Sir PS -

Finding a replacement mirror...is proving to be more challenging than I originally thought....If I am to cut my own, where do I begin...

I think I may have been 'misinterpreted' when I was discussing the 'cut to save' technique... Here's a quicky diagram, irreverently (in kind jest.. in my best 'Chingrish', to show 'how to doo':

Galvo_SexChange.jpg ..point being, since an 'X' really does not need all the 'translation' (length) of a Y, if both mirs are-of equal length (vs, ie: CTs, where the X is already a short, 'stubby' box, compared to the elongated, taper-cornered Y..) then you can do what is being proposed in the 'sex change' graphic and simply adjust the (former Y, now, 'X'..) galvo in the mount, to account for the shortening-up, and then re-tune both amps to play well together, again...

This is far-easier (..assuming you didn't already toss the Y remnant... than sourcing a new mir, at least for the 'time being'... And *certainly* easier than cutting from scratch, especially with über-delicate 0.8mm th stock! This is the technique often used by us old Sea Dogs, 'in the field', when spares are either not available, forgotten in the shop or... doh! you already broked the first set, and this *is* your spare Y..

Dig?

Lemme know if this all makes sense, or if I am just bats..
cheers..
j

[Pitts]

Hi
Cant help with your current situation but you have some very experienced guys here offering help.

I have been in exactly the same boat myself. Jian ( of DT scanner fame) sent me new mirrors at no cost ( I was ordering another scanner at the time so no freight $$ for them).

What I would like to share is my policy of NEVER and I mean NEVER leaving the mirrors uncovered at anytime (other than live beam tests) when the lids off the case.

Jian always (or at least used to) supply a little cardboard box corner that covers the mirrors / scanner for shipping.... KEEP IT..

The moment I have one of mine open on goes the box cover and a couple of bits of masking tape.

I am currently doing an upgrade on an RGB with a Cambridge 6215. I even use one of Jian's box covers for that.
Strange, one of the best scanner companies in the world doesn't supply a cover but a modest Chinese scanner manufacturer does.. there's hope yet !!
Its also worth mentioning the really neat little case you get the DT scanners in when they arrive.... well presented I think.

I no sooner had covered the 6215 when ooops !! dropped a screwdriver and as usual, as if by some invisible force, it went straight for the scanner.
The cover was on disaster avoided. Beat ya this time buddy !!

So as a veteran of the broken mirror syndrome, may I suggest this as an idea for when you work on, handle, ship or whatever the scanner... put the cover on tape it down.
Also keeps the dust off while you work on the beast.

It has paid off for me several times and as recently as last week..

By the way I changed the broken mirror free hand very carefully and the DT40 Pro unit needed very little retuning... runs like a dream.
Maybe I just got lucky.

Cheers

Ray
NZ

[pschlosser]

Great advice, gentlemen.

Since I cannot get my hands on a mirror that's an exact (visually) replacement, I see the wisdom in reusing the broken mirror by flipping it.

As soon as Brother Jon and myself can arrange the loan of one of his jigs, I'll be on my way.

[mixedgas]

Real scan heads enclose the scanners. At least the ones I grew up using do. medical and marking systems do. Maybe there is a lesson here about adding a small metal box to most designs. In fact we mounted our scan heads on pivots, that rotated around the beam path,....

Hum, methinks its time to reinvent what works, yet again.

Steve

[dash8brj]

Good advice re the cardboard box supplied with the DT-40W (or any scanner for that matter) - I have kept my cardboard cover in place on my scan set since it arrived, only removing it to have a play (to make sure the scanners worked. Once I have lasers and have them aligned I will then remove the cover to do live beam tests and final alignment. I've already broken a mirror on a cheapy chinese set and do not wish to do so again with my expensive DT40W's

[ThatLazerGirl]

I've done exactly what dlsi_jon suggested above with perfect results every time, only I've never even clipped the edges. I just took what was left of the mirror, cleaned the slot in the shaft, replaced the remaining part of the mirror in the slot with the broken side away from the shaft, and used 2-part epoxy to glue it on the opposite side from the front surface mirror. Then it became the X-axis (if it wasn't already) since you don't need the full mirror's worth of room on that axis. No new parts, no retune, simple as can be. Really, seeing how wide that mirror is you can probably still keep it on the y-axis without losing much scan angle.

[dsli_jon]

..Now preserved in The WikiMother... http://www.photonlexicon.com/wiki/in...in_Progress.29

j