. : Dye Laser : .

Here will be a guide on DIY dye laser. As soon as I will be able to invent/reproduce a dye laser deserving to be a subject for the guide. What does mean "deserving"? The laser should fit to the next simple requirements.

1. The dye should be easy to obtain. I.e. it should be readily present at common stores or it should be rather easy to extract from things being readily sold in common stores.
2. The solvent should be easy to obtain. I.e. it should be readily present at common stores or it should be rather easy to extract from things being readily sold in common stores. (Of course the design of the laser should be resistant to the solvent action. The most troublesome solvents are acetone and dimethylsulfoxide.)
3. Ideally the laser should be superradiant (no mirrors, no alignments). Here may be a compromise:
   the laser should be able to operate with common aluminium mirrors. (Of course it will be harder to create and tune such a laser, but the level of efforts will still be reasonable.)
4. The laser should be lamp pumped. Only this type of laser promises to provide a decent output energy.
5. Laser should give this 'decent energy'. (above ~1 mJ)
6. If possible the lamp should be of one of the widely spread photograpic types.
   The compromise is usage of hand-made lamp. However here is a strict limitation for the vacuum required. (Regardless what others tell, the fridge compressor gives only 60..70 torr. Not 20 torr as they usually say. And nobody has ever seen one, giving 5 torr, as required by most lamps.)
7. The expenses should be reasonable concerning cost of the parts and cost of the working.

Until I find out such a design here will be kinda 'web report' on the interesting intermediate results.

Note (6.7.19) generally speaking this design has already been found, and the guide is here. But still the results given here may be of some interest, so it was decided to keep this file online.

SYSTEM #1

It was created by the steps of Jon Singer. http://freeweb.joss.com/tjiirrs/015.html
The pump system is the simpliest two stage Marx bank generator, made of two fast capacitors (Maxwells, 30 nf 35 kV each). As a peaker there are 3 TDK doorknob capacitors 40 kv x 2000 pF each. The scheme contains two dischargers. The main one controls switching of storage capacitors to the series connection. The other one separates peaker capacitor from the other scheme during the charging process. Both spark gaps are homemade, air filled air pressure type, ball-to plate, (ball has 15 mm diameter), having an adjustable spacing from 6 mm to 15 mm.

The lamp is quartz xenon type, ~7mm bore and 9 mm outer diameter. Inter-electrode spacing is 106 mm.
It was bought at the internet spare parts yard. And its seller described it as being "a strobe lamp from an airplane." The advantage of this lamp is that it has rather small parasitic length (length of non-illuminated
part). Its disadvantage is rather high fill pressure (may be even higher than 100 torr) so it explodes easily when overloaded.

The laser cavity is based on a glass tubing with 6 mm bore and 8 mm outer diameter (It was later replaced by one with 4 mm bore and 6 mm outer diameter) and length of 200 mm. The ends of the tube are o-ringed into perspex plates. Those ones also carry windows and hoses. All seaalings are made by glue gun. All this stuff is mounted on a perspex plate. Ath the ends there are mirror mounts. The back one is home made (alike ones that many other lasers here have) and the other one was bought (to check it out.) As it appears it has very similar properties in precision and stability, but it is definitely more handy.

The mirrors are from a dead helium neon laser. An old LG-106, bought on a radio market. Unlike Jon Singer, I decided not to push myself, and installed them to form a stable resonator (concave side towards the dye cell.)
The lamp is warped to the cell by kitchen aluminium foil (Of course the shining side towards inside)
The connection to the Marx bank is made by wide strips of aluminium tape.
The pump is from an aquarium fountain.
The pipes are from automobile glass washing system
The solution is Rhodamine G in isopropanol and variations.

Resulst:

• At first laser refuced to oscillate at all. At any pump levels. After a hard filtration of the solution (more than 5 times) through coffee filters, the first successfull observation of lasing was made. The spot was pretty weak and appeared rarely. After that a car fuel filter was added to the solution circulation contour. The things became much better.
  
• It appeared that there is rather evil dependence to the dye concentration. Almost everywhere it is written that 1e-4 mol/l is needed for the lamp pumping. However this system almost completely refuses to operate even at 7e-5 mol/l. Its optimum seems to be at 5e-5 mol/l and the lowest band of operation is ~1e-5 mol/l. I.e. the range of operationability is less than one order.
• By reducing the cell bore from 6 mm to 4 mm and by replacing the output coupler by one less transparent for green (naturally using a piece of full reflecting 'beam-turning' he-ne mirror) it came a success in bringing fluorescein to lasing.
  
  The working range of the fluorescein is much more strict: from ~2e-5 mol/l to ~4e-5 mol/l. Pretty easy to miss out.
• It was found out that isopropanol (at least in this system) may be successfully replaced by vodka (naturally vodka is mixture of 40% ethanol with 60% water and some minor taste additives.) The common vodka from a drunkstore works well. The range of operational concentrations, gain values at different concentrations and pump levels, and brightness of the laser spot are equal (in limits of measurements errors) on vodka and on isopropanol. The single difference is their thermooptics. Isopropanol tends to focus laser beam with some distortions. And the vodka gives strong wedge. (Strong enough to force You to find a better alignment place, than one having been set up by he-ne laser)
• On Rhodamine G at optimal concentration the laser endures insertion of two glass plates (microscope sliders) into resonator.
  On fluorescene - it endures only one glass.
  On the optimal (gain) mixture of fluorescene + Rhodamine G one can place up to three glasses into the resonator without quenching.
  It means too low gain for aluminium mirrors.
• The laser is rather stable when operating at ~1 Hz repetition rate when working with dye circulation.
• Without dye circulation the laser is capable to give 15..20 pulses till quenching.
  After that it needs 10.. 15 minutes of rest. Therefore the pump is not essential part of the laser, however its usage simplifies cell filling and solution filtering. (It's easier to add pump and fuel filter to the circulator, than filter all by Your hands. Especially when You know that single filtration is not sufficient - the solution absorbs dust fromout the laser cell, and You need to filter it again.)
• At 1 Hz rep rate the average power is low enough to be below homemade Peltier calorimeter resolution.
  I.e. pulse energy is less than 10 mJ. I would say: "Less than 1 mJ"
• The laser beam does not make recognisable traces on carbon paper. Even in case it's been focused by lense.
• By choosing the concentration of Rhodamine G one can tune the laser from "swamp-green" to "reddish orange". Table of colors says that it is 560..610 nm.
• Fluorescene spot barely changes color with concentration variations. And indeed the range of working concentrations is too narrow. Table of colors allows do designate this color as 540..550 nm.

SYSTEM #2

I can't say that this system follows Burlamacci steps. However I admit that I definitely knew about his works. The coincident term is cell bore diameter. All other parameters and ideas are quite different. Lamp diameter does differ, reflector type does differ, concentrations do differ drastically. And the obtained results are mostly different too.
The thoughts about the possibility to get superradiant lasing of dyes at very common pump levels follow from the next considerations:
The people's results with dyes superradiant lasing under nitrogen laser pump. There are messages about sucess with 50 microJoules from the nitrogen laser. The elementary recalculation of the light intensity to the emmission ability and from the emmission ability to the temperature of the equivalent black body leads to the conclusion that equivalent light density may be obtained when plasma themperature in lamp is 25000 K (It was assumed that both lamp and nitrogen laser spot have length 20 mm, and the nitrogen laser spot strip has 0.1mm width.)
If we take not the exact light density but the total gain, then with lamp length of 10 cm the necessary intensity can already be achieved at 12000K plasma themperature (and it is not too high for almost any lamp).
And the other consideration. The previous variant of laser has shown 30% gain per pass.
So if we redice thickness of the amplifying layer by 40 times (from 4 mm to 40 mcm) we'll get the gain value 1.3^40 ~ 36 000 times per pass! (However we'll need to increace dye concentration by 40 times) Both issues lead to the thought that "superradiance is somewhere around". And in order to obtain the superradiant lasing one should not rush for the very high pump levels. One should fish for it using high dye concentrations, like people do when using pumping by a nitrogen laser.
Marx bank and lamp are from the previous system (SYSTEM#1).
Laser cell is formed by a glass capillar tubing with length of 180 mm, 1.5 mm bore, and 2 mm outer diameter. (Tubing from a CCFL lamp.) At the ends of the cell the perspex stoppers are placed. Each of them carries windows and hoses. The cell is tightly glued with glue gun.
No measures were taken for any kind of "windows aligning".
The lamp and capillary are warped together by kitchen aluminium foil (close coupling)
The pump is taken from an aquarium filter.
Layout, pipes and solution - as in previous laser. Except of dye concentrations that are about (and above) 1 mmol/l
Here is how the cell looks like.

And here is how the whole assembly does look.

Under the laser cell on the board (which serves as an 'optical table' for several years already) one can see a typical pink spot. It appeared when previous version of this cell did leaked. At the very moment when I was going to photograph it. After liquidation of the mini-Fukusima consequenses, I made a new cell, which is represented on the photos above. If You take a look at photos of commercial dye lasers, You may note that all those are equipped with a special pan. Just for case of leakages.

Results:

• After filling by Rhodamine 6G in isopropanol solution (1 mmol/l, yes this time it is really 6G, not G), and after switching on, the laser immediately began to lase. No additional tunings was needed.
• Spot of this laser usually has a ring shape. Diameter is about 2 cm and thickness is about 0.5 cm at 20 cm distance. The ring does rarely show itself as uniform one. Usually it has one or multiple "hot spots". The ring is very sensitive to thermal loads and to dye flow. It changes diameter (and position) from pulse to pulse, its shape usually distorts too.
  
  
• In dye flow mode the number of pulses, that laser is able to bear without quenching, is nearly a half of the same number when the dye flow is stopped. I.e. dye flow does interfere with lasing. However the rest period (the time before the laser is able to lase again) is smaller when dye flows rather then when it is stopped.
• The optimal dye concentration (by visible amount of light in the laser spot) is ~2 mmol/l.
• Threshold concentration is ~0.2..0.3 mmol/l and the spot is barely noticeable.
• In addition to the rhodamine in isopropanol the laser succeeded to operate with the next liquids:
  • Rhodamine 6G in vodka, 1..2 mmol/l
  • Rhodamine G in vodka, 1..2 mmol/l
  • Fluorescene in vodka, 5...7 mmol/l (note that this concentration is above the solubility of the fluorescene in isopropanol)
    
• When the laser spot is catched by a lense and carefully focused onto a piece of (black) coper paper, one can get a small point of damage (less than 0.5 mm in diameter) on the paper. It allows to estimate the output energy value to be nearly 1 mJ. With taking into account the huge ratio of the lamp diameter to the cell diameter, one may expect that over 90% of the lamp light misses the cell and goes directly to heat. In this sense the 1 mJ of output looks like... achievement (moreover - its more than gives 1st system).

SYSTEM #3

The smaaler variant of the SYSTEM #2. Its cuvett(i)e is made of CCFL lamp capillar tubing, having 1.5 mm bore and 2 mm outer diameter.
There are two variants of the cuvettie - the one has length of 50 mm (uses single lamp) and the other has length of 90 mm (uses 2 lamps).
The lamps are china photo flash lamps, straight shaped, with inter electrode spacing equal to 26 mm. Lamp outer diameter was 3 mm, lamp length (measured over its envelope) - 40 mm. The lamp(s) was(were) warped to the capillary by kitchen foil.
As usual the ends of the cuvettie were plugged into perspex parts carrying hoses and windows. The sealing was done by glue gun. (By the way it was found out that the white glue gun, that was perfect for vacuum, appeared to be not suitable for dye lasers. Glue gun was found to be totally unable to keep alcohols and water-alcohol mixtures permanently, however it holds oil in Tesla coils for ages. Among the tested glueguns the most endurable was black sort - it takes about to weeks until it leaks. The white one and the transparent one are much less durable.)
Power suppy is the generator described here on the site in the section devoted to homemade low inductance capacitors. (Here it is used without any additional capacities.) The double-Maxwell marx bank if used would explode the lamps to hell.
In the double lamp variant the lamps are connected in series.
The dye circulation contour is the same as in previous systems.
The solution was mostly Rhodamine 6G in vodka, 2 mmol/l.

Results:

• The laser began to lase immediately without any tuning, but... The spot is weak and hardly recognizable. Here are photos of the spot "as is" and with enhanced contrast for better visibility.
  
  
• The divergency is bad too. Sincerely speaking if not for the experience of the previous systems one may not understand that this spot means superradiance and not something else.
• The longer cuvettie (the one with two lamps) gives sligthly brighter spot and slightly lower divergency. But the difference is not principal.
  
• The laser works at repetition rate of 10 Hz. When the dye flow is stopped the solution begins to boil inside the capillary in a few seconds. (The laser spot in this case disappears of course.) In flow mode the laser can operate much longer (the main limitation is that duct tape which keeps lamp and foil begins to melt)
• usage of capillary tubing from a thermometer (bore is 0.3 mm, outer diameter is 3 mm) allows to reduce divergensy to the 'laser level' (3 mm spot at 100 mm from laser) but the output energy here is neglible. And the pump appears ro be unable to provide a sufficient dye flow, so the laser practically operates in hydrostatic mode.
  
  (because the spot was a very weak, brightness had twisted up - the second picture)
• Photos of spot from the laser with a long capillary from thermometer and a large lamp (as in the first system). The second photo was made with a reduced exposure.
  

ON THE DYE CONCENTRATION

As it is seen from experiments the dye laser is pretty critical to dye concentration.
Usually they type necessary concentration in millimoles per liter (rarely in milligrams per liter). But it is not very suitable. The reason is that:
Let us assume that we need a solution of Rhodamine G having a 0.1 mmol/l concentration.
The molar mass of the Rhodamine is about 470 g/mol. It means that one need to take 47 milligrams of the rhodamine and put them into one liter of alcohol. Sounds simple unti You try it in real. The first problem to face is to measure 47 mg with decent precision. It will appear that household scales aren't able to weight something smaller than 0.2 g adequately. And I am saying not about steelyard or kitchen balance.
Even a good samples, well known for photographers of times of film photography, or the new electronic type ones (marked as "0.01g precision") provide that grade of accuracy.
One can say: "no problem, we'll take 0.47 gramms of rhodamine and put it into 10 liters.."
The problem is that You usually haven't got 10 liters of alcohol. More common situation - You have less than a liter." The hight expense of the dye is also unnecessary. And moreover if You finally ended with a bucket of the dye solution... just imagine the scale of the disaster if it was poured onto the floor...
If still want to use scales, then follow the next way. Take, say, 200 mg of the rhodamine (the amount that can be adequately weighted) and dissolve in a small volume of the solvent, capable to dissolve the taken amount of dye. (For isopropil alcohol it is about 100 ml, for the ethanol-water mixtures it may be even less.) At this stage You will get a ~2000mg/l solution. In order to get 47 mg/l it is only needed to dilute the solytion by 42 times.
Simply saying - to take about 5 ml of our concentrated solution and pour them into 200 ml of solvent. (200 ml is usually enough to feed a small laser.)
The described procedue is affordable, but usually people do not use it either.
First - it bothers. If You have accidentally missed the concentration of the solution or its amount (It had seemed that 200 ml is enough, but appeared that all solution gone to pipes and fittings), then You have to make some additional solution, and its volumes and concentration begin to be expressed not by round numbers. Bottles, cans and vials (with solutions of intermediate concentrations) start to increase in number, and it usually does not make You happy.
The second reason to find the other way is: what to do if You do NOT know the initial amount of dye. Let's assume that You deal not with a dry dye powder, but with a marker juice for example.
Practically it is the simpliest way to define the solution concentration by beam fading.
The correct way to do this is to use a special device - spectrophotometer. But it is not for home. The 'kitchen' way is to visually observe fading of laser pointer ray.
Use green laser pointer for rhodamines, blue (or at least violet) one for fluorescene, and violet pointer for the dyes generating in blue spectrum (coumarines or optical whiteners.)

Here are photos of beam fading in lasing able rhodamine(6g) solutions:

	Lit with Purple laser pointer	Lit with Green laser pointer	Lit with Red Laser pointer
without dye of course it does not lase
0.07 mmol/l for lasers with mirrors
2 mmol/l for superradiant lasers

Here are photos of beam fading in lasing able fluorescene solutions:

	Lit with Purple laser pointer	Lit with Blue laser pointer	Lit with Green laser pointer	Lit with Red laser pointer
~1*10^(-5) mmol/l for lasers with mirrors
~5 mmol/l for superradiant lasers

Marker Lasing

At last I have found a marker that lases. (I know that other laser DIYers had already done that a long ago. E.G. Sharpie Accent Highlighter by Jarrod Kinsey and Jon Singer, but none of those are available in the area where I live). A bit ago I came to the conclusion that any yellow-green marker that gives clear (not turbid and not cloudy) juice with strong fluorescence can be lased. At least one needs to try different solvents and extraction routes. However all my previous attempts failed due to the fact that liquid from markers was almost opaque and refused to settle (for years oO). But recently I ve found one that gives clear juice when being extracted by water or vodka and gives rather clear solution (at least it settles quickly) with isopropanol. This is a Brauberg (tm) Yellow-Green marker (text highlighter)

Open it, fill it with small amount of water, wait for several minutes, get the porous stuffer out of the marker and squeeze its juice directly into a cuvette. It gives clear liguid with strong greenish fluorescence. (Dont fear if there will be a layer of foam - it is normal and it will settle soon) It lases rather easily when being pumped by a small quick-hand assembled open air nitrogen laser:

The nitrogennie has electrodes in the form of aluminium tubes 10 mm in diameter and 32 cm long and wings 32x12 cm each. Please note that the power of the laser is boosted by a double gapped rail spak gap (see at the right of the photo). The laser uses common air (the ruler over the laser channel is used to reduce noise, not to fill it with pure nitrogen). The dielectric sheet is 0.125 mm thick mylar. The overall value of the spark gap is 6 mm (2x3mm), so the trigger voltage is 15.6 kV (I've recently found that in most of my spark gaps each mm of the gap does closely correspond to 2.6 kv).
The marker juice (water extract) lases in green color

Please note that all photos are taken at the full lights in the room (not with long exposure in the darkness). Also note that che cuvette being used has grinded sidewalls, so I had to stick some sticky tape to them in order to make'em more transparent. So the dye beam is a bit diffuse.
Here it comes that a marker has been found that gives a clean solution and lases. At least under the nitrogen pumbing. Tests with lamp pumping are foregoing...
...A hour later. The superradiant lamp pumped laser (see above SYSTEM #2)was filled just with the same solution (marker-water juice) and lased gracefully:

Another marker that lases gracefully is yellow ViviLite Highlighter.

The marker contains rather high volume of ink, so just open it, get out its porous stuffer, and just squeeze it into the cuvette. Usually its enough to fill standart 5 ml one. Concentration is enough to lase under the pumping by air tea laser without any lense:

Yet another lasing marker is yellow Sprint highlighter. Procedure of its milking is rather tricky. It contains a little of ink so get its porous stuffer, place it over the cuvette and add water drop by drop. When You feel it is full, squeeze it. Repeat again. Dont overdo with water. It may take two or three markers to fill the cuvette. The solution You get is a bit cloudy, so the lasing is diffuse. Here goes photo of the marker

It lases in green. And only with cylindric lense. Nothing special here, so no need to place the photo, I think.

Another yellow Brauberg that lases. In general it seems that markers having the same color and made by the same company have the same contents independenly to their formfactor. So I will not count this marker as different.

Another marker that lases - yellow BASIC highlighter. A bit better than Sprint but a lot worse than Brauberg.

Next one in turn is yellow STAFF MANAGER textmarker. Guess what color it lases in? Yes in green. It appears that all yellow markers lase in green. To milk this one dip its porous stuffer in ethyl alcohol (it was wriiten here "isopropyl" but it was a typo, in reality the marker with isopropyl gives thick turbid solution that refuses to settle), wait until it is wet and squeeze into cuvette. The juice is transparent but lases only with lense.

Yet another one addition to the number of green-lasing markers: "format textmarker". Its stuffer is pretty wet and contains plenty of juice. Just squeeze and lase. It lases good. Comparable with Brauberg and Vivilite. It lases under the air-nitrogen laser pumping without a cylindric lense at high (for markers) distances:

And the next one is the first (at least for me) marker that lases somewhere out of green. Meet the violet STAFF MANAGER textmarker! To milk it just squeeze its porous stuffer into a cuvette. However the squeezed juice refused to lase as is. The key is to dilute it by isopropanol in 1:2 proportion (2 parts of IPA per 1 part of the marker juice).

This is how it looks like.

And here is how it lases:

Yes it lases weak and only with lense. But at last IT IS NOT GREEN! Occasionally I will try it with lamp pumping.

Pink-Yellow-Red-Orange markers

The procedure of bringing markers of red part of spectrum to lase is rather complicated and tricky. We will discuss it on the example of relatively wide spread Stabilo Boss markers. By the way here ith the photo of them all:

I am intentially showing them together, because their bodies differ from each other only by a tiny shade of color and when you look at a standalone Stabilo marker it is pretty easy to mess it up with another color. On the photo there are shown (top-to-bottom) the orange one, the red one, the pink one and the purple one. (At least their seller called them so.)

Ok then we'll start with an orange one. This is how it lases:

And here is how to milk it. Need to note, that recently a more advanced procedure of milking the markers was developed. The key was to acidify the solution to make it settle. I call the procedure "vinegar milking". Please refer here for details.
First of all break the marker and get its porous stuffer.

Squeeze the stuffer into a suitable vessel.
Here is how the stuffer will look like after the sqeeze.

And here is the juice You should get.

The juice is completely opaque. Next step is to dilute the juice by isopropyl alcohol. Typically You will want to add as little IPA as possible, due to You want the highest possible concentration of the dye. Dont do so. If You add too small amount of isopropyl alcohol You will end up with opaque solution with fine particulate matter that never settles. The same will (probably) happen if Your IPA contains too much water.
The proper amount of IPA is about 20 ml per the whole juice from one marker.

When proper amount was added the turbid liquid begins to coagulate and settle. The left image is taken almost immediately after dilution. The right image is several minutes after.

The next step is to filter the stuff. Yes, feel free to use a pair of layers of toilet paper here.

The filtered liquid looks transparent. It still contains some junk but not very much. (The juice that hasnt been coagulated remains opaque even after triple filtering.) The left image is the filtered liquid. The right image shows how deep goes the beam of nitrogen laser into the solution. This concentration is a bit low to lase under my nitrogen laser. If You have more powerfull one it probably will lase.

In order to increase concentration of the solution let it dry. The one dried for 3 days is shown on the left photo. The volume of the liquid has reduced by 6 times. (Note that the cup contains combined extract from four(!) markers.) Now the concentration is enough to lase - see the right image. However it is low enough to lase without a cylindrical lense.

Here are the shots of Stabilo Boss Orange Juice lasing in the lamp driven superradiant cuvette. The spot isnt very bright and is comparable with Rhodamine G (not 6G! 6G is far far brighter!), so the practical use is doubtfull. But the fact is that orange marker can be lased under the lamp pumping.

This is Stabilo Boss Red. Its milking process just the same as described above. Its dye concentration is a bit lower than in orange and pink ones so it has to go through a bit more drying.

It lases in orange-yellow. Being reduced 8 times in volume it still requires a cylindrical lense.

Here is with lamp. Maybe its not much to see, however it clearly shows how this thing DOES NOT lase.

This one is Stabilo Boss pink. Its milking process is the same as one described above.

It lases in orange-yellow. A bit shifted to red in comparison with the red labeled marker, but it can be due to the concentration effect. Requires cylindrical lense and still contains some turbidness so the lasing is diffuse and has halo.

This one does not lase with lamp too. One can see only diffuse red lit area and no pronounsed spot. Compare this photo with one of superradiant cuvette when it lases and You'll feel the difference.

Laundry detergents

Yet agane the job was done by Jon Singer and Jarrod Kinsey. However the detergents they found arent easily available at my whereabouts. However the Tide(tm) seems to be so widespread that there seems to be no place where it is unavailable.

Jon Singer proposed that it could be lased if there was a way to concentrate its juice. The procedure appears to be rather simple. Put some Tide powder into a jar. Add twice of its volume of 70% isopropyl alcohol. Shake, filter through a piece of cloth. Then set aside for a pair of days to settle. Then pour the (rather) transparent liquid into another jar and let it dry for several days. The liquid should reduce its volume three times to lase under cylindric lense and ten times to lase lensless.
The resulting liquid will be not very transparent, see the photo below:

Yes in is not very clear but it does not prevent lasing.

On the left: Tide's juice lases without a cylindrical lense. Photo was taken in the dark. On the right: Tide's juice lases under cylindrical lense. Photo's taken under common lighting conditions.

Here's another photo of Tide's lasing. The liquid was let to stay a day in the cuvette and became more transparent. The results, as You see, became much better (the photo's taken at full room lights, note the absense of lense here).

It's a pity but this is the case when I can't say that further on I will try it with lamp pumping. In my lasers I use glass tubings, that probably cutoff the ultraviolet rays. Or there is too low current load for the lamp to emit UV efficiently. In any case in my lamp systems neither optical brightener has ever lased.

The next specie is Textile White laundry bleacher. It is not pure optical whitener. And it really contains some free oxygen substance (some peroxide probably) but it does also contain the optical brightener too.
Here is shown ho its bottle looks like

The liquid in the bottle is very clear and transparent:

And it is ready to lase "as is":

It lases nice without a help of any cylindrical lense and pretty far away from the laser (up to 40 cm).

The next one is "Laska, Shining of the white" liquid laundry detergent.

Its bottle contains viscous turbid liquid almost opaque to the view.

Inspite of the turbidness it still can lase. It requires the cylindric lense to produce a compact spot however. As one can see the lasing is possible even in turbid media if gain exceeds losses.

Another one is "Vanish Oxi Action" liquid bleacher/detergent "more white than white". Here is the photo of its bottle

Inside the bottle there is a slightly bluish transparent liquid with a violet fluorescence and a strong tendency to produce a foam.

Like "Textile white" it is ready to lase just from the bottle. It has a bit higher threshold in comparison with the mentioned "Textile white", but still easily lases without any cylindrical lense.

Cuvettes for lasing dyes under the nitrogen pumping

Quick tests for dyes lasing are best performed with the use of nitrogen air laser. Usually I use a commercial cuvette with two polished walls and two grinded walls. I covered the grinded walls with a transparent sticky tape to make them more transparent. The dyes agreed to lase under those conditions.

Then I wanted to see If one can do the same without a commercial cuvette. And if the one doesnt want to make a glasswork. OK then. I got a CD-cover box, cut some stripes of the plexiglass (or polysterene to be more precise) and hot glued them into a kinda cuvette. The work was done purely by hands and the cuvette appears to be poorly aligned. But the dye still lases

And then I thought what if the cuvette would be completely misaligned. I hot-glued a triangle cuvette and filled it with dye. The lasing is still prominent (see the stripe of orange light on a paper next to cuvette):

However the bright spot in the center of the stripe just disappeared. It seems the bright spot is due to lasing that uses the cuvette walls as resonator and the stripe is due to superradiant lasing.
If we put into the cuvette a stripe of light with higher length to width ratio the output beam will become more tight, because rays that are going at higher angles aren't affected by amplification. This can be done for example by cylindrical lense:

The last remark: If You want to make a similar cuvette, keep in mind that they appear to be SINGLE USE! It means it is impossible to wash the dye out of the cuvette and You are either to stuck with a single solution of single dye, or trash the cuvette and make a new one.

Safety notes

Inspite of these lasers seem to be small and innocent they can produce severe damages to eyes or equipment. See the next video and take safety measures.

Agane about markers

Yet another bunch of yellow-green fluorescent markers. Naturally they lase and naturally in green spectrum.

"90 green Recycled PET" yellow highliter ( lases @~20 cm unfocused)

ViviLite yellow highliter ( lases @24 cm unfocused)

ErichKrause yellow highliter ( lases @ >45 cm unfocused)

Still no exclusion from the rule that any yellow-green highlighter with transparent juice will lase.

ErichKrause yellow textmarker in a resonator type lamp laser. The green from markers appeared to be unbelivable hard to obtain in this type of laser. Finaly it agreed to operate but it required to create a new laser for this - two maxwells in paralel, each rated to 40nF 50kV. The geometry of the laser was changed many times untill the risetime(by light) became 200ns.

Some new things were brought by Writewell green highliter. It a first pure green (not yellow green) marker that lases. It is weak and does it with lens only but still some new here.

Another amusing thing that a progress was found where nobody expected it - among nonfluorescent markers.

It appears that Centropen permanent red marker aricle N8576 gives juice that is visually undistinguishable from a solution of Rhodamine 6G. Moreover it lases nicely. Just as R6G solution would do.

This is how it looks like.

Dont mess it with centropen red permanent marker article N8566. The latter does not lase at all. It even is not fluorescent.
Back to "true" Centropen. I was able to lase it both in lamp driven superradiant cuvette and under the nitrogen laser beam. (left and right photoes correspondently)

Excited by such a success i continued the search among nonfluorescent markers. Some results were obtained with Brauberg permanent red marker.

It lases rather poorly. And here are the snapshots. Left one is with full room lights on. The right one with some darkening.

Further progress in the permanent (intended to be non-fluorescent) was obtained with Berlingo red permanent marker

Berlingo lases almost like Brauberg (red permanent)

Yet next of them is "Multi Marker" permanent red marker

"Multi Marker" lases still more weak than centropen, but much better than Brauberg. However it may not be clearly seen on the photo, but it behaves really better. E.g. it requires cylindrical lense, but it can lase when displaced +-5 mm from its focus (focal length was 23 mm)

It appears that 8576 is not the unique among the Centropen family. Another great laser marker is Centropen permanent red marker aricle N2846. It seems to be filled with the same ink as the 8576 (most probably - alcohol solution of Rhodamine 6G).

Centropen N2846 lases great even without any focusing

Orange and pink highlighters have great fluorescence but their juice is just opaque. In the simpliest case one can apply here the milking procedure that was described above here (see Stabilo Boss description). Recently Ive upgraded the milking procedure to be more quick and give better results. It is described here. And here are some results:

Here is "90 green Recycled PET" pink highliter

Despite all efforts and attempts to keep the dye concentraton high the soluton appeared to be rather dilute and it was only enough to lase under the Longtitudinal pumping. However the spot is bright so one can say that it lases good.

Without lense it did it in concentration of 3 markers per 1ml, but rather weak.

Edding345 orange texmarker.

Edding345 orange lasing. Lases with lense only. Milking procedure is common as for all red-orange markers.

Edding345 pink texmarker.

Edding345 pink lasing. Lases with lense only. Milking procedure is common as for all red-orange markers.

ErichKrause purple highlighter. Rather good marker. Vinegar milking procedure gives a lot of juice. under the nitrogen laser pumping it lases with lense only, but it is clear that it will lase under direct beam if having been dried out 3-4 times.

ErichKrause purple mixture for laser with resonator.

ErichKrause purple lasing in laser with resonator.

ErichKrause pink highlighter. Rather good marker. Vinegar milking procedure gives a lot of juice.

ErichKrause pink lasing in laser with resonator.

Marker types

RESULT:

Three kinds of fluorescent dyes are used in markers:

• Rhodamine-B
• Rhodamine-6G
• Coumarine-540

A few other dyes with greenish and bluish fluorecence are used there as coactivators and color correctors. Identification and separation of those additives are very hard to perform.

Highlighters use five kinds of fluorescent inks:

• green turbid ink;
• yellow transparent ink;
• yellow milky ink;
• orange milky ink;
• pink milky ink;

Permanent markers use many types of influorescent inks and two kinds of fluorescent ones:

• red transparent ink based on Rhodamine B;
• red transparent ink based on Rhodamine 6G;

Further on about markers

The work on analysis of available resources does never end. Some of them (resources) become history and new ones appear day by day.

Here are two newly available permanent markers containing rather pure Rhodamine 6G. Their juice is quite similar to the one of "Centropen" by view and by lasing properties.

The 1st one is the Crown Multi P-505F marker.

Here is how it looks like:

And here is how it lases under the beam of my reduced pressure nitrogen laser. The dye solution has very low concentration (only a tip of marker washed by 5 ml of alcohol). You could find out that the concentration is low all by Yourself. Just by noting how deep the beam of the N2 laser falls into the cuvette an by color of lasing (Didnt You know that in dilute solutions Rhodmine 6G can lase in green?)

The next one is the Power Line 200 marker.

Here is how it looks like:

Here is how it lases. Agane here is my low pressure nitrogen laser and again the concentration is low enough to produce green light.

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