Glass Diffraction Grating

[bloompyle]

I am looking for the opposite. A lot of people have the 10,000line/mm or some equally high line count. This is nice if you want a lot of beams. However terrible if you're trying to separate the lines of a multiline laser.

I am looking for <500line/mm, this way there will be great spacing between each line, and I can very easily separate the lines of my lasers. It's a problem when some lines are only a couple nm apart, such as my PMS/REO.

If you know of anything in the 300 or 500 range, let me know!

 

[SKeeZ]

the lowest i could find was 31 grooves/mm or 802/in: in an echelle grating from thorlabs

 

[bloompyle]

That's a bit low, and priced a bit high. $30 max, unless it's a mirror; $60 max.

 

[SKeeZ]

I see now! i thought you were asking for a grating that was 300-500 lines an INCH not a MILLIMETER. thisd should be much easier to find now.
EDIT: it didn't, unless you want to drop $100 on a high efficiency thor-labs mirror grating...

 

[hakzaw1]

OK Im no expert--but I think they come these ways.

Plain thin plastic like Glenn gives away with every purchase his are mounted in a 35mm slide
-about the same as we see in laser show glasses.

Some --like the free one we send when you buy an JETLASERS laser are glass on one side and the film on the other--they work nicely and I always put the glass side facing the laser.

AND some others are two pieces of glass with the film inside-<the most expensive

I do not think they sell any that are not like these that are plastic or glass.

I have taken a JL DG and simply attached it to a FS mirror way cheaper Than buying a reflective DG- line gratings and some cross lines are in the front of many cell phones (second layer)
And huge ones can be found in a flat monitor between the front and the rather nice thick plexiglass layer..
The free ones we have now (JL)are smaller than before at 15X15 mm

the lenticular lens that I gave Herun came from a GB at the show forum by member Displaser=IIRC he only asks for 5 or 10$ and they are HUGE(5X7) all thickish plastic and ez to cut into small lenses- that al I know or think I know- reflects of a CD or dvd make a rether crude DF.[[[[ hak

 

[bloompyle]

The type sealed in glass would be best.

Just as long as they have a <500ln/mm count, I will be happy.

 

[hwang21]

The DL website says 50 lines/mm... :thinking: and what's the difference between fan and grid/dot? Is that horizontal grooving vs both horizontal and vertical grooving? For an Argon, I'd want a fan transmission grating, right?

 

[bloompyle]

Fan would keep all of your orders on a horizontal plain. Grid is both X, and Y. Dot would be grid, but with grids of grids.

In English, you would have several splotches of dots that probably turn and move around, rotating around each other when you turn the grating.

Transmission means it passes through, a reflection mirror is more efficient, and it reflects your orders back at you, but that's more money.

Are you looking for many orders? Higher line count, just one on each side of the spot? Smaller count. Smaller the count will also give you more space between wavelengths.

If you want a lot of orders in the X, and Y, for lots of colors and wavelengths, then a grid. Just the line with a few orders making up that line, get a fan.

Dots only really look good (in my opinion) with one wavelength. Like on a tip for a pointer, otherwise it's a lot of clutter/noise. That's just my opinion though.

 

[hwang21]

Would the fan produce lines like A or B below?

A) ****** ****** ******

B)
* * *
* * *
* * *
* * *
* * *
* * *
And I'm not sure I understand what you're saying with the higher/lower line count. Lower count means more wavelengths, higher count gives you more colors? :thinking:

 

[bloompyle]

A.

Ok. An order is the spectrum produced. So in an 8 line argon, the 8 lines between 457 - 514.5nm is your "order". The fewer the lines, the fewer orders.

Compare the following to their pictures for a visual example.

1000 line/mm single axis (fan)

13,500 line/mm dual axis (grid)

I'm buying the following one now.

300 line/mm glass sealed grating

 

[hwang21]

Ah ok so a higher line count will produce many orders, more than a grating with a lower line count, but less space between each order and between each dot in each order, correct?

 

[Cyparagon]

I am looking for the opposite. A lot of people have the 10,000line/mm or some equally high line count. This is nice if you want a lot of beams.

You've got this backwards. A higher line density means more spread and fewer beams. You want something like 1000l/mm

[deleted] Either way, I've got the cheap 500l/mm grating and the 1000l/mm gratings. The 500-count has more beams and less spread, I assure you.

Prove it for yourself. Look up the wikipedia article on diffraction gratings. You'll find an equation that has the angle as a function of the distance between slots. Graph this, and you'll see.

 

[hwang21]

:thinking:

 

[bloompyle]

You've got this backwards. A higher line density means more spread and fewer beams. You want something like 1000l/mm

I beg to differ..

I have used both 1000 line, and 13,500 line. The 1000 line gives me 2 orders (one on each side of the zero order) with great spacing between the lines.

The 13,500 gives me 5 horizontal and vertical on each side, and some in between, and very close spacing.

I do want low, I have 1000, trying to get as low as possible. I just got a 300.

 

[The Lightning Stalker]

bloompyle:

That is the exact opposite of what you're looking for. A lower line count will put the patterns
closer together, not farther apart. Too many lines though can give you another problem,
especially with transmissive gratings. The diffraction angle can become so steep that it will
be stopped by the grating itself and will have you scratching your head and saying, "The
gratings, they do nothing!" See the http://laserpointerforums.com/f70/grid-does-nothing-ir-85631.html thread.

 

[bloompyle]

That honestly goes against what I have seen with my own eyes.

My high line gratings split, and work just fine, but the spacing is minimal. Low line count spaced them out very well.

Example being my PMS/REO. With the high line count, the 3 lines between 629 and 635, made one oval spot. The 1000 line splits them up no problem, and there is a clear spacing between them.

That is what I have see with my own two eyes.