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CDBEAM777 01-10-2014 08:38 PM

Now Completed Optically Corrected P73 HH Design
1 Attachment(s)
Hello Folks,

While waiting for the final drivers from Lazereer for the "Lawgiver ll"....I decided to tackle a project that I have seen many requests for...but NO serious attempts at doing...A Hand Held unit with an Optically Corrected Mitsui P-73 LD. See the drawing !!!

As usual... I have used what I have learned from Laser Projector apply to the challenges of the Hand Held format. Although I have beat the drum multiple times... that we should..." Think Outside the Cylinder "...this design is a 2"(50.4mm) OD x 6"(152.4mm) Long - typical HH Cylinder Geometry unit!! Turns out that a cylinder is the most compact geometry for the design needs of this project !!

How many times have you read..." The P-73 is a great and affordable diode...BUT....I HATE THE LINE "...Well...It is WAY past time to give this LD a pair of glasses !!!! OR...apply correction optics to the Holy Grail P-73 !!!


As you can see, the unit uses two ( 2) 18650 LiPo cells, placed within the lower half of the construct. I have started construction with a solid Aluminum rod with 2" (50.8mm) diameter and about 5 3/4" (146.05mm) long. The Aluminum rod will be milled down to a semi-circle geometry for about 4" (101.6mm) of the overall length. This milled area will then provide a flat platform where the LD mount, Correction optics and Driver will reside.
The solid bottom section will serve as a heat sink and a home for the LiPo cells. A bore hole will then be milled, almost full thru, for the LiPo cells. The back cell will present the + battery contact to an isolated contact point. A bore hole thru the back Ally Rod will then allow a + wire to pass/travel to the I/O switch and on to the driver. The driver will be grounded to the main Aluminum body.

The front and back of the unit will employ 1/4"(6.35mm)thick Aluminum plate/dics to finish the ends and contain the LiPo cells. The front plate will have a typical contact spring to engage and secure the LiPo cells within the underside bore. The spring will connect the cell - to the Aluminum body There will be an aperture hole in the front plate to provide beam exit. Both front and back plates will be secured to the main body with machine screws.

I want to showcase the heart of the optics, so the front upper half will be a clear 1/8"(3.175mm)thick Acrylic tube which will cover the front 4"(101.6mm). This cover could be Aluminum...but I think clear Acrylic will look good !!! The outside OD of the main body will be highly polished.


A critical aspect of optical correction for the P-73 is that a 2mm Fl Collimation Aspherical lens MUST be used to start the correction sequence. The position of this very small lens relative to the output of the P-73 MUST be right on for alignment. accomplish this alignment / positioning a special adjustable LD mount must be used.

This special mount, from LSP, is a very small brass box-like unit, threaded on the front to accept the standard M9 retainer barrel. The back has a square retainer plate attached where the P-73 is captured and bolted to the mount body. The retainer plate bolt holes are slightly oversized and THIS is what provides X / Y adjustabillity for the diode. The retainer plate, with captured LD, is moved...up/down - left / right to find the optimal position. When the best position is located, the retainer plate bolts are then tightened down, locking in the optimal LD===> Lens alignment. The LD is NOT press fit into the retainer plate but just a snug fit. The fit provides radial adjustment within the retainer plate. The heat from the LD transfers mostly by front and back LD collar contact. It works very well.

The LD mount / holder used is the "Mitsubishi diode Correction optics kit" from Laser Show Parts. A 2mm Collimation lens mounted in a brass retainer is also from Laser Show Parts. These two components used together start to correct the astigmatic nature ( Read... like a line ) of the P-73 LD.

After the beam correction has been started by these two components ( Holder+Lens )...Then ...the optical correction process must continue by putting the beam thru two (2) Cylindrical lenses. These lenses are labeled "Plano Convex" and "Plano Concave" on the drawing.

In my build, I will custom machine an Aluminum mount/holder to put the lenses at the optimal distance and in correct perpendicular relationship to the beam. Note: The lenses will be secured to the Aluminum mount/holder with a very small amount of clear epoxy. LSP does offer Cylindrical lenses of the correct design/power and holders for those lenses.

The distance between the Cylindrical lenses ( Plano Convex and Plano Concave ) is absolutely critical to achieving a good beam spot. The distance from the 2mm Collimation lens to the first Cylindrical is also important and must be set correctly to achieve a good beam spot.

I have used a set of Cylindrical lenses I had left over from previous experiments. The distances for THESE lenses work per my drawing. The Lens set from LSP may have slightly different distances. It is an easy thing to do some experimenting to find the optimal distances. Once the optimal positioning has been determined, THEN the Cylindrical lens and lens mount/holder can be secured( Bolted down ).

In Closing

I am hopeful my end result will be a fairly compact HH unit with a well defined tight beam spot ...NO LINE !!!
I have used this exact correction method in projector builds with excellent results !! I should be able to obtain approx 1.0 Mrad divergence with a Nearfield beam @4mm. I will likely use a driver set to around 1W of Red Beauty out the front end !!!!!
Stay tuned for pics as the build unfolds. Although this project is not a " Combiner " the strict DOES combine a great LD...with corrective an HH format !!! Another first for " Terrawatt Labs" !!! Hot Diggity !!


Tmack 01-10-2014 08:56 PM

Re: P73 "Red Light Therapy" CORRECTED
Hot dignity indeed ;) . I've seen you come in multiple times on threads about the infamous 638 spot. Time to put your skills where your beam is. I know I, and everyone else, is really looking forward to any updates with this build. Lazeerer had implemented a lens that semi corrects the line, but it's not quite there yet. Can't wait to see mr. Combiner at work :D

CDBEAM777 01-11-2014 12:32 AM

Re: P73 "Red Light Therapy" CORRECTED
Mr. should work !!!!! Just cramming things into a smaller space !!! All the same optics work with a larger with ANY new design...there are ALWAYS unexpected turns and challenges !!!...and one the build unfolds !!

Drilling a 3/4" bore hole for the LiPo cells ...thru almost the entire length of the Aluminum rod outta be a trip !!!

Actually....this build will be somewhat straight compared to some of my previous units !!! So...indeed...Hot Diggity for that !!!


Dr. Combiner hey !!! Ya... " Put da Lime in da Coconut " I say !!! Hahahaha

CDBEAM777 01-12-2014 01:45 AM

Re: Optically Corrected P73 HH Design -1W and NO LINE
:tinfoil::tinfoil::tinfoil: Improved Drawing with Plan View added.


CDBEAM777 01-19-2014 02:29 AM

Build Pics #1
8 Attachment(s)
For this project, I thought I would post a series of the build unfolds. See attached pics, Start of machining the 2" Aluminum Rod Stock.

Doing a 3/4" bore to a depth of 5 1/2" into a 2" Dia. Rod takes some time to set up and a fair amount of cutting oil. The bore drill must be parallel to the Rod stock. If the bore went out of alignment... the x-y bore location would be off at the hole bottom...and result in a real problem on the back side. Luck was with me....all went straight and true as planned.

The 18650 cells fit with a small amount of clearance into the bore hole.

As you can see....the length of this rod stock was at the very limit of my small end mill...but, the clearance was just enough !!!

The final two pics are of the Adjustable Mount I will be using.

CDBEAM=======> :tinfoil::tinfoil::tinfoil:

Note: You can be sure that lessons learned with this build will give a boost to my planned build with a NDG-7475 LD ( Green Extreme. )..should corrective optics be needed !!

Tmack 01-19-2014 04:32 AM

Re: Optically Corrected P73 HH Design -1W and NO LINE
Man you never cease to amaze CD .. I'm really looking forward to seeing that clean beam.
( and the lawgiver 2) :D

LaserCo 01-19-2014 05:09 AM

Re: Optically Corrected P73 HH Design -1W and NO LINE
Holy Grail!! - I Just had to chime in on this project you've got cooking up!
Nice Job with the machining as usual! - fantastic skills!, wish I had such tools.

CDBEAM777 01-19-2014 01:57 PM

Re: Optically Corrected P73 HH Design -1W and NO LINE
1 Attachment(s)
THANX GUYS !! Really appreciate the comments. :p:p:p

I am really a very novice machinist !!! What I call a " Hack Machinist " But...I REALLY like machining !! It is very, very rewarding to generate a concept, draw it up in CAD ( Many, many times)...and " sculpt " it from Aluminum !!

I work out the clearances in CAD and try to incorporate flexibility in the design. Then...follow the drawing, change things on the fly when it makes sense...and ENJOY the build !!! I go slow and know the capacity of my tools...and generally...things will turn out as planned !!

HAHA..." In every block of metal, lies a Laser Build waiting to be released " !!

Really...ALL our Hand Held units use corrective optics !! ( Collimation Lenses )
This design is just an extension of that need as dictated by the P-73 LD.

The NDG-7475 LD may also need a " Set of Glasses " to tame that beautiful 520nm Green beam...and based on the work done by Lasertrack over at PL ( Search 1W 520 ).....I think it might need correction !! If it does, this correction concept may come into play !! If it does not need correction....even better !!!!!

Exciting times !! Hot Digity !!

Oh...I have coined this build as...The " Dragon's Head " ...rhymes with RED....
and will breath the fire of red/orange photons !!:knight::knight::knight:


jander6442 01-19-2014 04:48 PM

Re: Optically Corrected P73 HH Design -1W and NO LINE
You could always order aluminum pipe with the thicker ID and the bore the desired diameter after that then turn the outside just enought to get that shine.

CDBEAM777 01-19-2014 05:22 PM

Re: Optically Corrected P73 HH Design -1W and NO LINE

Originally Posted by jander6442 (Post 1271486)
You could always order aluminum pipe with the thicker ID and the bore the desired diameter after that then turn the outside just enought to get that shine.

Well... yes, one could....but...then...what about internal LiPo cell positioning ?? Perhaps a 3/4" ID Aluminum tube, secured to the inner ID of the 2" OD tube ?....and then...

I would have to cut the top half off the front portion of the 2" pipe to provide a place for the optics. Then, to mount the optics, I would need to machine and bolt down an Aluminum plate which would be the optics platform.

This IS another path to do this basic concept. Only real drawback is that the extra Aluminum mass in a "solid rod design" provides a passive heat sink for heat dissipation.

A take-away on the " Dragon's Head" design is that we need to do two things;

1) Provide a geometry for two (2) 18650 LiPo cells
2) Provide a geometry which accepts the necessary LD and correction optics.

The " Over-Under " design of the DH packs this into a 2" x 6" cylindrical geometry. I cannot think of another way to make things more compact. The option of having the LiPo cells located behind the LD + Optics would, IMNSHO, be WAY to long....You would get a smaller OD....but about DOUBLE the length !! That would look like crap. Don't like it !!

For now...I will stick with the 2" Solid Rod. The hard part is over !!! That 3/4" bore was a PITA....but mainly because my End Mill is too small !! I have been plotting for a larger one for several years !!! These things take time !!!!

SOooo, that's my logic. If anyone has more inspired ideas....speak up !!! I am always open to new concepts !!!

Thanx !

Wolfman29 01-19-2014 08:36 PM

Re: Optically Corrected P73 HH Design -1W and NO LINE
I would just like to point out that there are some conservation laws that are at work in the fat beam of the Mitsu diodes. In particular, I am talking about Liouville's Theorem, which indicates that phase space can never be decreased. That means that, while you may change the shape of the beam, the product of the divergences and the initial beam widths can only ever increase. That is, if the beam width is, at some point before correction optics, 0.5mm x 1mm and the divergence is 1mrad x 3mrad (just for example), you'll never be able to get a beam with a phase space product better than 1.5 mm^2 mrad^2. For example - it would be impossible to produce a beam that is 1mm square on both sides with 1mrad divergence, no matter what optics you use. In fact, most optics will actually increase phase space, decreasing beam quality.

So use optics wisely, and don't expect to get out more than what you put in. ;)

CDBEAM777 01-20-2014 01:42 AM

Re: Optically Corrected P73 HH Design -1W and NO LINE
I looked up Liouville's Theorem ....Well....THAT was an interesting read !!!

I really do not know how to reply to Wolfman 29's observation. I understand that the initial LD emitter geometry has major impact on what can be done with any corrective optics. That IS where it all starts !! The laws of physics/optics always rule....and one cannot get out better than what goes in !!! I do think it is very appropriate that the limitation of corrective optics be duly noted....I thank you for pointing that out.

And, perhaps if I were a Physics Major in college or Optical Engineer....I could respond with some impressive answer....alas...I cannot.....and I do not pretend to be well educated in Optical Theory.

I DO know that Cylinderical lenses correct the asymmetry of the P-73 a reasonable degree...they do not deliver a perfect circle, they do not even provide a perfect square. They do change the shape of the P-73 beam...from a line...into a round cornered rectangle...that is slightly wider than it is tall. And for our purposes, deliver a much improved display..IMHO !!!

What I lack in formal Optical training, I hope to make up for by sharing my ideas, my practical experience and my passion with everyone.


Shakenawake 01-21-2014 05:52 AM

Re: Optically Corrected P73 HH Design -1W and NO LINE
here's a picture I took a while back, thought it was appropriate. Hot diggity!!!

CDBEAM777 01-21-2014 12:18 PM

Re: Optically Corrected P73 HH Design -1W and NO LINE
Nice Pic !! Bing the term " Hot Digitty " The term does have foundation in USA Pop Culture...although...likely predating the average LPF DOB by 30 years !!....But...then again....Vampire stories go back centuries !!! So there !!! Hahahaha Nothing is truly new....just " Updated " CDB

CDBEAM777 01-22-2014 01:17 AM

Build Pics #2
6 Attachment(s)
Well....Further progress....Milled out the backside for the + wire passage and removed 1/2 the diameter for aprox 4" in length.

Chips were falling like snow flakes in the shop.

As you can see...we now have a flat platform to mount the optics and the LD mount.

This mill step took the weight down....but, the remaining Aluminum Main Body still has a fair amount of weight ( and mass ).

Next step, Mill an Aluminum bar stock down to mount the Cylinderical Optics to.

These things take time...and the garage workshop is a bit chilly !!!....But...this is my entertainment and relaxation !!!! :pop:


CDBEAM777 01-31-2014 03:59 AM

Build Pics #3
7 Attachment(s)
Dragon's Head progress; :wave::wave:

See attached pics. I/O switch mounted....I have a small push on/off switch ordered..not arrived yet.

Corrective Optics baseplate machined from Aluminum. Lenses not yet epoxied in place. Ready to do optics set up to finalize lens positions.

Most of the major components placed on the optics platform...but not yet mounted.

LD mount still needs the P-73 and the 2mm EFL collimation lens.

The Aluminum main unit weighs 21.1 OZ....over 1 1/4 lbs ( .65 Kg )....good for the P-73....or the NDG-7475 !!!

These build's take a lot of we are in an " Undiscovered Country " !!!

Hope you enjoyed the post. Stay tuned !!! MMmmmm.... Perhaps the new Optnex 700mW diode will eventually find a home in this format. It IS A Multi-mode....and will need a pair of glasses !!! /OO\


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