0:00welcome to another session with my
0:02little tangerine tiger
0:04um it’s been a couple of weeks now since
0:07i’ve really played with this machine
0:08because i’ve had
0:09other things to deal with but hey we’re
0:12getting back on the case now
0:14last time if you remember um we managed
0:17to establish that the
0:18expanding beam could be controlled
0:22with a beam expander and i made my own
0:25little crude holder
0:26to put the three times beam expander in
0:29front of the rf laser
0:31it was adequate to prove the point that
0:34the beam expander worked
0:35and that we went from a two millimeter
0:38beam to about a six millimeter beam
0:41whether we looked at it about 100
0:42millimeters away or in fact i checked it
0:44about three meters away as well
0:46it looked to be doing a pretty good job
0:48of making the brim
0:49beam pretty parallel so
0:54i then inquired of cloud ray
0:58if there was such a thing as a piece of
1:01standard kit that would allow
1:04me to fix that onto the front of this
1:07you can buy it everywhere type rf laser
1:10there must be some adapter
1:12plate that allows me to connect one of
1:14these
1:15beam expanders straight onto the front
1:17there
1:18they didn’t appear to be so i designed
1:20something and sent it to cloud and asked
1:22them if they’d make a prototype
1:24the good news is they didn’t
1:29what they found instead was a standard
1:31plate of some sort from somewhere
1:33now i don’t know where they found it
1:34from but they’ve
1:36sent me a a standard plate
1:40b a two times magnifier
1:45so we can test the two and the three
1:48to see what effect they have now here is
1:51the plate that they sent me as you can
1:52see
1:53it fits perfectly it only locates on
1:56these four holes at the edge here
1:58but they’re pretty accurately machined
2:00holes and when i
2:01check in there it looks as though it’s
2:03pretty concentric
2:05now the great news is all i have to do
2:08is to screw this in and job is done
2:12but i’m not going to do that to start
2:14with now although i’m anxious to get on
2:16and use this machine
2:18i don’t think i really ought to rush it
2:20because i really ought to understand
2:22how this thing works before i start
2:24trying to make it do
2:25something i want to go about this
2:27journey of discovery in a much more
2:29logical fashion
2:30than i did when i knew very little and
2:33was floundering around in the dark with
2:34my china blue machine
2:36my first task will be to measure the
2:38power
2:39that is coming out of this device it
2:41says it’s 30 watts
2:43i think that that’s 30 watts cw
2:46continuous wave mode
2:47now i’ve got no idea how this machine is
2:50programmed at the moment and what’s
2:51going to come out of here
2:53but because this is a pulsing system
2:55controlled by the pwm
2:57so it could well be that the pulse is 30
2:59watts but
Transcript for Let’s See What We Have – Beam Combiner (Cont…)
3:01the pulses are regularly spaced out for
3:03example
3:04such that we’ve got 50 on and 50
3:07off now what that means is although
3:09we’ve got 30 watts per pulse we shall
3:11only have an average power of 15 watts
3:13so what i measure on here
3:17is a little bit of an unknown at the
3:19moment that doesn’t make any difference
3:21because what we want to find out is the
3:23relative change
3:24of power as i move further away from the
3:27beam
3:29technically you wouldn’t expect the
3:30laser beam to lose its power with
3:32distance
3:33i know it changes its diameter with
3:35distance but the power should still be
3:37there in the beam
3:39i want to prove that before we start
3:42because i want to get to 1.3 meters
3:44which is about where you are at the
3:46moment
3:46because i don’t want to lose power as i
3:48go around this very small machine
3:50now i’ve already got my little doohickey
3:52test program set up on the machine that
3:54runs for 20.5
3:56seconds well i’m going to check first of
3:58all what’s happening straight out of the
3:59tube here
4:00now i’ve got something in the region of
4:02about maybe five
4:04or six seconds before the beam will
4:06start coming out of here
4:07one other thing that i’ve noticed and
4:09i’ll have to explore
4:10further this is completely cold at this
4:13moment in time
4:15i have read somewhere that it takes
4:17maybe
4:1810 minutes for this to warm up to its
4:21proper output value seems a bit strange
4:25but hey that’s what
4:26one of the specifications i read said
4:29for the moment we’re going to check it
4:31from cold dead cold because this has
4:33been sitting here for
4:34well as i said a couple of weeks now
4:4018.2 to 38.
4:43we started off at 18.2 we finished up at
4:4638.
4:48the difference in temperature the
4:49temperature rise is 19.8
4:52and we’re using the times two scale
4:55which means if i multiply 19.8 by 2 i
4:58get 39.6
5:01this is a 30 watt machine so hey
5:04we’re doing something pretty remarkably
5:06good here
5:09well this time we’re starting off at
5:10about 18.6
5:14now from all the work that i’ve done
5:16previously i would expect to lose
5:18something in the region of about four
5:19percent
5:22per lens
5:27just as a guide
5:31so dividing that by that
5:36gives me 95
5:40so that means i’ve lost five percent
5:43over two lenses which is not bad
5:46that’s the times three device
5:50let’s try the times two device
5:53and see what that gives us here’s the
5:56times two
5:57that i’m just about to tighten this up
5:59onto its shoulder
Transcript for Let’s See What We Have – Beam Combiner (Cont…)
6:00if i loosen it off just a little bit
6:05but i could physically move this maybe
6:08half to three quarters of a millimeters
6:11either way so that’s a pretty
6:14dodgy old thread in there that looks
6:16like a much bigger loss
6:1836.6 37.8
6:21that’s another one another what that’s
6:24been lost
6:24because we’ve done times two do i
6:26believe that
6:27[Music]
6:28no
6:32because it’s possible remember what i
6:34said to start with this thing has got a
6:36warm up period
6:37that things might have changed in the
6:39five or ten minutes that this has been
6:41running
6:42so the check that i shall now make
6:46is take the beam combiner off and check
6:49the wattage again do i get the same
6:51value as
6:52two times is about what i expected four
6:54percent loss per lens
6:57okay so i’ve got a piece of card there
6:58set up uh
7:001.3 meters away from the front of the
7:03tube
7:04and i’ve got no beam combiner on it at
7:06all i’m going to see it fire 100
7:08power at it just quickly just to find
7:11out where i am
7:13and there is the answer now we do a bit
7:15of a real target test
7:17because first of all i stuck a piece of
7:19acrylic
7:20onto the card so that there’s somewhere
7:22for the energy to get absorbed
7:24if it burns through the card and i don’t
7:27want to set fire to my cardboard
7:29but i’m also using a card there which is
7:32in front
7:32which has got a quite high kaolin
7:34content in other words
7:35it won’t catch fire i hope
7:39so i’m hoping to be able to get a decent
7:41scorch mark which tells me the real size
7:43of the beam when i can hold it on for
7:45long enough
7:55there we go i think that’s probably
7:57about as big as the bean is going to get
7:59i would say that that’s close on 10
8:01millimeters
8:03we know we’re starting off with
8:04approximately a two millimeter beam i’m
8:06gonna put the times three beam combiner
8:08on and i’m gonna move the laser very
8:10slightly
8:11to the right
8:23i’ll measure it properly later on but
8:25it’s somewhere between seven and eight
8:27so
8:27it’s not too far away
8:36i have to say that that is substantially
8:38better
8:39but i would probably put that at about
8:43six millimeters we’ll just check
8:47we’re still in the right place yes
8:57i’m quite pleased with that
Transcript for Let’s See What We Have – Beam Combiner (Cont…)
9:01because okay we are getting a power loss
9:05but i was only expecting 30 watts to
9:08start with
9:08we had to have 38 watts average power
9:13okay which is a lot more than i was
9:16expecting to see
9:18and we’ve only got 1.4 watts loss right
9:21let’s turn that noise off
9:23i’m gonna have to deal with that in some
9:24way later but um let’s just live with it
9:27for the moment
9:30so yeah six millimeters
9:3310 millimeters
9:37and seven and a half millimeters now
9:40six is a very nice number because that’s
9:42the sort of number that i would expect
9:44to see
9:45out of a glass tube laser
9:48so we’re definitely going to go with the
9:51times two
9:54now i just spotted something rather
9:55strange and interesting
9:57[Applause]
9:58which we should have to go back and
9:59check that there
10:01was with the beam combiner on
10:06this here is with the beam combiner on
10:11that doesn’t make sense we can’t have
10:13gained
10:15because we’ve gone further away i was
10:18expecting a loss
10:19further away so i’ve actually taken the
10:22wrong two numbers here
10:28okay so this stability and warm-up thing
10:32seems to have some truth in it because
10:35when i re-run the numbers i’m getting
10:3737.6 watts
10:40when i move away 1.3 meters with the
10:43beam combiner on
10:46i’m getting 38 watts so i’m still
10:49getting more watts close up
10:51than i am when i’m 1.3 meters away now
10:54that sounds like a miracle
10:56but in fact i think it’s probably just
10:58the system is not capable
11:00of resolving to these 0.1 of a watt or
11:03something like so we’re losing 7
11:05because of the beam combiner and nothing
11:08because of distance which is brilliant
11:10news some reason or other
11:14we seem to have a 40 watt unit almost
11:18i don’t know but it turns out this unit
11:20might be
11:2140 watts um there is no external
11:25difference between a 30 watt and a 40
11:27watt unit
11:28and the paperwork definitely said this
11:31was a 30 watt unit but i’ve
11:32got half an idea that that was cloud ray
11:36devaluing the unit for customs purposes
11:38because
11:39the 40 watt is about 400 more
11:43so yeah they’ve saved quite a lot on
11:45duty by doing that
11:47but anyway we’re going to put this back
11:49together now that we’ve
11:50checked everything out i’m going to
11:52assemble the mirror and then we’ll go
11:54through the setup procedure i’ll set the
11:56beam up
11:56i’m going to go and set up my y-axis now
12:00um i’ve got the beam approximately
Transcript for Let’s See What We Have – Beam Combiner (Cont…)
12:03through the hole i’ve already had this
12:04machine set up and the y-axis once so it
12:06shouldn’t be too far out but normally
12:10this would be
12:11several stages to get this right but i
12:14don’t know how many is it’s going to
12:15take me let’s just have a go
12:21see what the second one is like
12:26it’s not bad it’s a little bit to the
12:28left isn’t it
12:29probably just to show too far so because
12:31it’s so close we should have to do it
12:32again you can always use the back of the
12:34targets
12:36because we’re not trying to get it on
12:37center we’re just trying to get two dots
12:39that coincide
12:40so let’s just make a target
12:43and we’ll see how close we can get with
12:44this one
12:48spot on so that was a couple of goes
12:52within getting wide but hey this is a
12:54bit abnormal because i wouldn’t normally
12:56have the machine
12:57set this way design some special targets
12:59for the mark ii head because there are
13:00one or two oddities about the head
13:02that we need to take into account so
13:06the first thing that i’ve done is
13:07manufactured a target like this if these
13:09fixing screws appear to be
13:11too long well they’re not too long
13:13they’re designed
13:15so that you can plug a target onto them
13:17like that
13:23and then at the other end of the stroke
13:24where we’ve got a little bit more light
13:27not bad just a little tweak to the right
13:31now this is where you just can’t get
13:33your fingers in there
13:34to adjust these screws and this is where
13:37you now need
13:38the access panel it’s on the side here
13:45now just about spot on it just so
13:47happened it was in the center of the
13:49target
13:50but that does not mean to say that it’s
13:53in the right place so we can use the
13:54back of that target
13:57on the table we can fire a spot down
13:59onto that target
14:03then we can drop the table down this is
14:05very very very slow this machine
14:08there we go three or four inches now
14:11we’ll check again
14:15and we’re out
14:26looks pretty good but hey we’ve got to
14:29do all that again now
14:30as i’ve warned you previously
14:34although we’ve got this thing set up
14:35mechanically square
14:37you need to just check to make
14:39absolutely sure that it is
14:42sitting upright and square so this is
14:45set up right in both axes and now we do
14:47it again
14:49there we go now that’s a nice round spot
14:51i have to say
14:53and it’s also nice and small
14:58remember we’ve had one attempt it
15:00probably is going to take three attempts
Transcript for Let’s See What We Have – Beam Combiner (Cont…)
15:02to get this set
15:04so it’s a very laborious process when
15:06you’ve got a slow table like this
15:09second pulse
15:12is out so we need to bring it
15:17across
15:25more a little bit more
15:32a bit more
15:37pretty well there now we’ve got to come
15:38forward a shade
15:43just a shade more
15:50too much
15:55that’s pretty good we’ve got another
15:56target here
15:58which is square and it’s got a little
16:01tab
16:02where you tear it off that tab needs to
16:04be to this
16:05outside edge but there’s a hole in there
16:08which
16:08make sure you put a hole in that corner
16:13and that’s the center that we’re looking
16:16for where we bounce off this mirror
16:19so let’s see how good we are for the
16:21center of the lens now
16:24not bad actually
16:28so we’re pretty good that way
16:32so we haven’t got to raise or lower the
16:34mirror what we’ve got to do is just
16:35bring it slightly this way
16:37with the y-axis adjustment which is over
16:40on mirror
16:41number two so just loosen mirror two off
16:45and it’s gonna come across what maybe
16:47three millimeters a quick pulse
16:52too much see if i can leave it loose
16:56there we go just about spot on and
16:58that’s how easy it is to set up wide
17:00we’ll just check it now that i’ve
17:01tightened it back up
17:04there we go so our beam is now passing
17:07right down the central axis of the lens
17:08and we’re going to get an upright
17:09and the final check i like to perform
17:15you’ve got to look at it at just the
17:17right angle because the light is wrong
17:20it’s not far off the center as you can
17:22see i’m pretty pleased with that for a
17:23set up
17:24now i said i wasn’t going to play with
17:26this machine
17:27until i’ve got it and understood it a
17:29bit more but
17:31i’m so fascinated by the size of that
17:33dot that
17:34i’m actually going to run a very quick
17:36dot test on here at 400 millimeters a
17:38second and 25
17:40power just to see what we’ve got origin
17:44and off we go
17:48obviously haven’t set the accelerations
17:50up yet i would say that they’re probably
17:52about 0.15
17:54dots that i can see on there
17:57they’re not they’re not 0.1 dots but
18:00they’re
Transcript for Let’s See What We Have – Beam Combiner (Cont…)
18:01they’re certainly all separated
18:04which for a two inch lens is pretty good
18:07going
18:07and that bodes quite well
18:10now i don’t want you to laugh but in an
18:13attempt to quiet this thing down
18:15i have modified the back panel
18:19so that it allows air in and i put an
18:21upward deflector on it to catch the
18:23sound
18:24maybe it will deflect the sound
18:25downwards
18:27let’s see how this works
18:32right this is make it any quieter
18:42a little bit
18:46take some of the high frequency away and
18:48certainly for the front of the machine
18:50here it doesn’t sound too bad at all
18:52i could live with this i think the
18:54extraction is now going to be louder
18:57than the rf we don’t need that noise do
19:00we
19:06it’s still annoying isn’t it um but
19:10hey i’ll leave it like that for a little
19:11while oh by the way um
19:13don’t worry there is plenty of air
19:16coming at the end here
19:17i’ve got uh i’ve taken the end panel off
19:19so all my air is exhausting at this end
19:22well this has actually been quite a
19:24successful session we’ve managed to
19:25establish that we’ve got
19:27a good beam we’ve got no loss of power
19:32and we’ve set the machine up pretty
19:35accurately
19:36we’ve seen the potential for getting
19:39very small dots
19:40at high speed and we haven’t even tried
19:43to set the machine to do it at the
19:45moment it’s doing it on its own
19:47so lots of promise
19:50but we’ve got lots of laborious things
19:53to explore and check out
19:55before we really get into the depths of
19:57this machine
19:58how does the rf tube actually work i’m
20:01about 80
20:03of the way to understanding how that
20:05works
20:06and it’s been a difficult process
20:08because
20:09there’s not much out there telling me
20:11how it works thank you very much for
20:13your time again
20:14and i’ll catch up with you in the next
20:15session
