Homemade ccd/cmos spectroscopic project

[G4Lab]

I'm very interested in building one of the video arrangements you describe and look forward to your further posts on what, why, where and especially how.
_________________
Rick Martin

Since Rick has thrown down the gauntlet on this I thought we could make it into its own thread. As I get older and more geezer like I realize the truth of the statement "the devil is in the details" So I propose that we start talking about such a project and break it down into its various sub projects. I will put an outline together with some points about each subject. I hope that list members will jump in and try some of thngs and also share what THEY have learned or already done along these lines because there are several threads on this site on this very subject.

If you google the web on the subject of spectrophotometer or spectroradiometer you will encounter descriptions of instruments that are essentially the same as what we are trying to do. Except the dispersing element (prism OR grating and they are both used in "real" instruments) is a removable hand spectroscope that we want to be able to use with our eyes if we want to. Also we are trying to not spend a million dollars on the project.


So the components of a spectroradiometer are:

1) An energy source. For what we are doing a quartz halogen lamp will furnish light from the near UV into the near IR or about 350 nm on the UV end and way past the 1200 nm on the Near IR where any sensor we are likely to come up with will peter out. Real instruments have deuterium discharge lamps for the UV range or xenon arc lamps or tungsten halogen lamps.

For what we want to do the fiber optic lightsource is perfect. It keeps most of the heat away from the gemstone and can be put and will stay where we want it. You do need to know whether the unit you are using has an IR blocking filter in front of the bulb. Most do and I recommend this because without it the fiber optic bundle may cook and the adhesives holding it together may scorch or color. But just like the astronomers who want to see IR if you want to extend your measurements into the Near IR and work with a camera without the IR filter, then your excitation energy source needs to have the near IR content in it. In some fiber optic lightsources the heat filter is removeable on a slider. others need a screwdriver. I would say leave it in place for the most part.

The new generation of LED lightsources is VERY interesting and cool (thermally speaking as well as neato speaking). But they arent what an audio nut would call "flat frequency response" They have a big peak at 480 nm or so. This is actually a bit handy when using the hand spectroscope because it brightens up the blue end of the spectrum where the eye isnt that sensitive.These are available in flashlights now that will blind you if you put three new triple AAA batteries in them and will keep blinding you for days. Similarly the MiniMaglite is well known to gemologists as a light source and there are a wide variety of such flashlights and bulbs . This is one of the easier parts of the project.

There are also microscope illuminators that have bulbs from 10 to 100 watts. Sometimes called Nicholas illuminators They are bright and could be used. But the typical fiber optic unit is 150 watts and has a fiber end of about 1/4 in diameter plus the metal jacket as opposed to a Nicholas illuminator which usually has an output lens of 1/2 or even larger. So the fiber optic can put more light into the stone and a Nicholas will heat the stome up faster even though it may only be 20 watts.

Here is a URL to Ocean Optics website which has a wealth of info on spectroscopy. They also have VERY cool products. You could whip together a spectrophotometric system from their building blocks very easily. And they have it all , lightsources spectros fiber optic cables everything. The spectra you see for the various lightsources match closely what you see in "the standard references".

http://www.oceanoptics.com/products/spectraloutput.asp

2) The next component would be the sample chamber on a real instrument
On our equivalent unit this is something to hold the stone, baffle it from light reflecting off its shiny surface, shade it and the entrance of the spectroscope from raw emitted light, (And your eyes too so you dont get dazzled) The old aluminum GIA spectroscope outfit had an aluminum base
with about a two inch diameter cylinder. On top of the cylinder was an iris diaphragm. You could close the iris just small enough to hold your stone. inside there was a 45 degree mirror and affixed to the plate was an American Optical stereo microscope Nicholas style illuminator. It could be set to shine into the cylinder and illuminate the stone from the bottom or you could swing it up and shine it down onto the stone. There was also an aluminum arm to hold a Beck wavelength spectrosope and a separate little pilot light to light up the spectroscopes scale. ( I think it was a Beck 2522)
This is a great idea only nowadays I would use LEDs for scale illumination.

Everything associated with this part of the project should be painted flat black so as not to reflect light which hasnt been through the gemstone.

Here is a great closeout item at Harbor Freight that you could use to hold the spectroscope camera combo. This is from China. When made in USA or even in Japan these kind of things were $200 now yours for $20. Designed to hold a dial indicator. Usually these things are magnetic but this one has a powerful suction cup to hold it to a flat surface. They have magnetic ones on sale for about $7 but I dont like having such strong magnets around and I dont work on steel surfaces. They have a few other jewelers tools that arent bad buys if you search around their site. They sell both on the internet and at your local store if you have one.

http://www.harborfreight.com/cpi/ctaf/D ... mber=93476

So much for the easiest part.
3)After the light or energy has been made and passed through the sample it needs to be dispersed into its spectral components. This is done by either one or more prisms, or combinations of diffraction gratings and mirrors. Usually the grating or prism is mounted on a table that can be rotated by a stepper motor. There is a slit which is at the entrance to the compartment holding the dispersion element which can be adjusted (often with a stepper motor under computer control.) Our units dont need to be quite so complicated. Our handspectroscopes are either grating units or prism units , maybe with focusable optics and adjustable slits. For this project I think those two features would be advisable. The OPL unit achieves its ease of use by very clever design but it is probably optimised for use at the eye. Having adjustments affords you a bit of flexibility but you have to learn how to use them Its not very difficult.

I like having both diffraction grating and prism spectroscopes. I know I'm an unrepentant instrument nut. If you can find a used R&J Beck instrument on the internet or somewhere , they had a microscope ocular which was the standard 23.2 mm in diameter. There are a very large number of people making gadgets to help amateur and even professional microscope users couple their video , film and digital cameras to microscopes (as well as astro telescopes, undoubtedly even a BIGGER business) So if you get a Beck Spectroscope it is easy to take out the microscope size eyepiece and insert a camera adapter that will drop right in with your camera attached. Some of the Rayner spectroscopes like the one Rebecca has been restoring were made by Beck. They also had one that would drop into the eyepiece hole of a monocular microscope. That could solve a whole set of thes requirements at one fell swoop. The late great Dr. Eduard Gubelin built a combo microscope spectroscope unit dedicated for gemological spectroscopy. Long time ago. If you think about it its perfect. Mirror to shine up though the gem. Table to baffle the glare. Probably an iris to set the gem on. Low power objective lens , probably less than 10x to make the field of view smaller and therefore only pick up specific light. Stick an eyepiece in, focus on the spot you like then pull the eyepiece and replace it with a spectroscope.The idea was not even new to Dr, Gubelin except for the fact that he was a gemologist. Zeiss , Beck and others had these items for chemical microspectroscopy in the very early twentieth centure maybe even late nineteenth. When examples appear on fleabay the prices make me shudder. I just watch and wish.


Here is a hand spectroscope you can buy for $49. I have no financial interest in surplusshed. I don't own one of these but have played with similar units.

http://www.surplusshed.com/pages/item/i1479d.html

Here is a wavelength scale unit. He quotes 5 degrees of dispersion between the C & F Frauenhoefer lines. This unit sells for $92.50 It is probably an India copy of the Jena spectroscope or more likely a Beck model.

http://www.surplusshed.com/pages/item/l3524.html

Here is a student table spectrometer for $125 You can use this with a grating
or a prism or multiple prisms to increase dispersion. You could mount your camera on this easily.

http://www.surplusshed.com/pages/item/i1430d.html

The above table spectrometer not magnificent enough for ya. Try this one for $325. Heavier built , more adjustments. spammer gemology students also know that the spectrometer can be used not only for spectral work but also can be used , if you are a total glutton for the worst sort of punishement, for determining refractive indices. You also might be able to make accessories for this or the above one to determine RI by the Brewster angle method or by reflectometry. If you are a lab rat.

http://www.surplusshed.com/pages/item/i1476d.htm

[jleb]

If your going to use a surplus IR filter, then you want to make sure it doesn't have any absorption bands, especially for iron, which they do make them with.. and that it will transmit the near IR up to the silicon detector limit.

The iron bands you can see in a handheld spectroscope. For the IR, shine your tv remote control through it and try to turn on the tv.. if it works, then your probably ok with that filter..

[G4Lab]

jleb makes a good point about iron contamination of glass. I noticed this before I knew much about gemology when I was a microscopy lab rat. Some brands of slides and even coverslips which are usually 1mm and 0.17mm thick respectively , when you would open the box would appear ugly green on edge and in the box there would be 100 edges facing you greenly. Other brands had a yellowish tinge and yet others seemed water clear. I did run accross info blaming the green on iron but I did not discern that the colors had any correspondence with price. But this is something also to keep in mind if you are building yourself an immersion cell or cube. Just look at the glass on edge and if it is anything other than water clear reject it.

The glass manufacturers use iron and other materials to make heat absorbing glass to block IR next to incandescent projection lamps. I have a few of those and am going to see if the bands are visible in the hand spec.

By the way I just ran across jlebs post about the refractometer. Pretty cool!! Please please make one of your light sources a 590 LED All the recent Jemeter wannabes have continued to use IR emitters at goodness knows which wavelength.

Back to the spectroscope project. Just so I wont be thought of as slavishly promoting Surplus Shed I have googled hand spectroscope and come up with a few links.

This company is in California but represents Kruess and shows most of their line on their website with US$ pricing. Would be good for someone
not wanting to send money overseas (but I cant imagine much of a problem sending any $$ to Kruess) They go from a simple tube spectroscope to table spectrometers.
http://www.finemech.com/kruss/spectroscopes.shtml

And here is Kruesses catalog of gemological instruments which is lots of fun to look through. Lots of cool things to leer at.
www.kruess.com/uploads/media/Spektroscopes_engl_06.pdf

An educational science goodies site, also featuring Kruess:
https://www.a3bs.com/shop/u.s.a./spectr ... 4_656.html

and a more general Kruess catalog that has a nice diagram of refractometers here:
http://www.precitech.net/.../Instrument ... ontrol.pdf

Hand spectroscopes are also available from pretty rock.com
http://www.prettyrock.com/php/gem-instruments.htm

He has some that look just like the ones from surplus shed and he also has the one from Nick with the digital readout and monitor for $3550 with a nice picture. Also he also has a GemPro for about $895 that you could stick a camera on.

Speaking of GemPro they make the $895 one above and sell the $3550 one for $3000 unless they just havent updated their website. They have been making PortaLabs and a really nice refractometer for a long time.
http://www.gemproducts.com/price.htm

A closer look at the Challernger:
http://gemstoneworld.com/hardware/gequip.htm

Jeff Graham sells two scopes and the Anderson Payne and Mitchell book:
http://www.faceters.com/equipment/gem_i ... copes.shtm

GIA has what look like OPL spectroscopes without the labels or maybe they are copies I dont know. They also have some of their older GIA 150 spectroscopes which used to be made by Meiji. They also have their $8,000 upgrade of the old aluminum one I described earlier.
http://www.gia.edu/geminstrument/myProd ... tartrow=1l

THe Gemological Association of Great Britain has a few things too:
http://www.gem-a.info/shop/prodType.cfm ... &Submit=Go

Neither of these two great organizations seems to have as much available as they used to. Maybe I am mistaken.

Manfred Eickhorst has a beautiful system. With the dollar down I would hate to inquire the price but I sure would love to have one of them. He will make a base to fit a spectroscope you already have. He shows the old Becks that GIA used to use, the OPL various iterations of Zeiss and his own which I would bet is made by the same folks who made the Zeiss and that isnt in the far east.
http://www.eickhorst.com/en/gem/spectroscopes.htm

You can also find hand spectroscopes on ebay , new ones from the far east and surplus shed sells there too. I have gotten a large number of them mostly at screaming bargain prices. But you can also get a problem child that needs renovating as Rebecca did. As of this writing a search on
"spectroscopes" returned mostly the India products from the Indian exporter or from surplus shed. There were also a few OPL and a Meiji at an outrageous price. Thin at this moment but I also just got a Hartridge Reversion scope which was absolutely the final statement in the field for About $250 delivered in a beautiful mahogany case with water white glass liquid cells and a stand and illuminator. But caveat emptor applies

There is a website that anyone who has read this far ought to go to .
It is published by a Greek mathematician and genius named Ioannis Galidakis. He built the mother of all table spectrometers using two Schott high index glass prisms. But he got hooked on spectroscopy by using a simple hand spec. His interest is a bit more emission spectra of lights but that is a topic that gemologists ought to at least take one cruise through. Being a mathematician he furnishes more equations than some of us might
need (Myself included) but if you want em they're there. He has also photographed lots of spectra and calibrated them and has lots of links and tells you how he did alot of it. I think a great classic website.
http://ioannis.virtualcomposer2000.com/ ... index.html

You can find alot of websites that want to teach you to build a spectroscope including some that want to use a CD as the grating. Ioannis builds and tests one of these on his site and concludes its fun but not really good because of spurious lines. A CD orDVD acts like a grating but its not one and the lines are curved so so are the spectra. The construction projects you see are either aimed at physics education or astronomical use. I don't think either of them are what we need here although the astro guys have truly phenomenal software that we could use. We will look at those later.

The purpose of the previous section has been to aid the reader in obtaining a hand spectroscope to use for this project. I have included everyone I could think of. If I have missed anyone, please somebody jump in. I tried to find a page I once saw at Meiji Techno who make very nice stereo scopes . They also made spectroscopes that were sold by GIA GAGTL and many others. But they arent on the website anymore that I can find.

So if we have a hand spectroscope in our hot little hands, then the next task is to attach it to a camera. Just to show that this has been thought of before take a look at this picture from a 1969 Exakta camera catalog showing an attachment they would make to record the spectrum seen in a Zeiss Jena hand spectroscope. They would do any scope you sent them the same way and this is essentially what we need to do only using an electronic camera rather than a film camera.

http://www.wrotniak.net/photo/exakta/ca ... e-hand.jpg

[G4Lab]

so after we get a spectroscope into hand we
4) then need to get and attach both optically and mechanically a camera of some type that suits what we want to do.

If we want to make wavelength plots of the spectrum then I would recommend a B/W camera. If we want to throw up onto a screen what we see through the scope then a color camera is needed. These can be video cameras, webcams, digital cameras, or even as in the preceeding illustration film cameras. Up until the last third of the twentieth century most spectrophotometry was done by photographic methods. Then the electric eye became widely available and scanning instruments soon followed. The gadgets those early workers had do determine the positions of lines and bands were truly impressive. Sort of like the gadgets they use for analyzing aerial photos.
Anyway the mechanical connection can be as simple as a block of wood to hold the camera, and another block of wood to hold the spectroscope, and a bar of wood to join them centered, and at the right height. Or if you have access to a machine shop you can build something more magnificent.

The optical coupling has a few more ways to skin the orange. But again this is essentially the same optical problem, as shooting a picture through a microscope, and the same methods will work. There is the completely lenless method, which was described by Basil Anderson a way long time ago, where in you remove the ocular from the microscope, and the lens from the camera, and let the microscope throw the image onto the film plane. Depending on the magnification of the objective (or the lens in the spectroscope) and the distance to the film and size of film a 35 mm camera could be used or sometimes they even would shoot right onto bigger film up to 8x10 in size. Usually there would be a projective eyepiece to add some magnification. In the case of our project if there is an eyepiece in the spectroscope, we probably cant remove it, and we probably wouldnt really want or need to. But this is one big advantage of the Beck scopes that can only be gotten used anymore. They had a microscope ocular which would make both the optical and mechanical mating to a camera a cinch.

In the microscope coupling example, the objective lens would be considered in what to expect in terms of magnification of the final result. In the case of spectroscopic recording, the analog of magnification is dispersion. So whether you are using a grating scope, or a 3 prism section Amici prism scope, or a five section Amici prism scope, or a table spectrometer with a wide dispersion grating, this item will be the first thing determining how much of the spectrum will be seen in the eyepiece and also on the camera sensor. The dispersions of the scopes may or may not be published. They vary from about three degrees to as many as 45 degrees. Most hand specs are designed so that you see the entire visible spectrum through the ocular. So you want you camera to pick up this entire amount. The scope is designed for you to view the spectrum with your eyes relaxed (at infinity) so just like when you shoot through a microscope you set your digicam at infinity. If you are using a video or webcam , same thing. It is possible to just stick a raw sensor up to the eyepiece with no lens in place and get a spectrum. But a lens will make things easier and especially a zoomable lens. If your digicam has one and most do, set it for infinity, and zoom in on a good bright spectrum until it starts cutting some of it out. Then back out some.

In addition to the dispersion angle, and eyepiece magnification there is also a need to consider the size of the sensor element. This is less important on a digicam where you can zoom in and out till you get what you want, and the zoom ranges are getting amazing like 12 to one on the digital video cams. But regular video cameras and webcams have sensors sized from about 1/4 inch square to socalled 1/3 inch and 1/2 inch and 2/3 inch and 1 inch Furthermore depending on the vintage of the sensor and camera there may be varying numbers of pixels for a given spectral spacing. If we throw the same size spectrjm on all of the above sensor elements as the size of the sensor goes up , the image on the video screen will get smaller UNLESS we have a lens to magnify it to the full sensor width.

Another thing to consider aside from the physical size of the sensor is how many pixels it has in its horizontal resolution specification. Things have gotten so good that even a cheapo $10 webcam probably has a horizontal resolution of 380 video lines. If you want to use a webcam the socalled High Resolution units quote 420 or 450 or 480 lines horizontal resolution. Video resolution can get up to about 1000 horizontal lines but most monitors cant display that much. Digital and computer monitors can with finer pitch dots and larger screen sizes. The things to consider are that if you are looking at the whole visible spectrum, call it 400 to 700 nanomaters or a span of 300 nanometers, if you project that onto 420 pixels you will have 300/420 nanometers per pixel or about 0.74 nanometers of spectrum on each pixel of the camera. It is probably desireable to have some space at either end of the spectrum (in video that is called overscan) and a zoom lens will allow you to size things to your liking and zoom in on spectral details.

Some optomechanical notes that might be helpful:
Webcams usually have a standard size small lens that has a 1/2 inch diameter barrel. There are eyepiece adapters made that will allow removal of the factory lens and ,mounting of the camera in a 23.2 mm eyepiece tube. Or a 30mm with an adapter. If you are going to use the existing lens you can adjust its focus by turning it in its mount. Often this requires opening the camera casing. Dont be afraid to do that. These cameras usually have 1/3 inch chips.

Security cameras may have the same lensmount listed above if they are socalled lipstick tube cameras. These weigh almost nothing and are very handy and inexpensive and available in both color and B/W. As you go up in camera head size the cameras will have C mounts or the almost identical CS mount. There are also microscope adaptations for these readily available. This mount is about One inch in diameter. These cameras come in all sizes from tiny lipstick tubes to older 1 inch vidicon tube Hi Res cameras with a C Mount. Most of them have a camera tripod mount socket on them. This has a 1/4 -20 thread (1/4 diameter and 20 threads per inch) to mechanically mount the camera.

Adapting digicams usually means rigging up something that fits the filter thread mount on the front of the camera. Nikon Coolpixes are popular for microscope because they have a 28mm thread which can be mated directly to a Leitz 10x Periplan ocular with the eyecup removed. You then drop this right into your Beck spectroscope and you are done.
jleb mentioned having trouble getting pictures with an OPL spectroscope. The exit pupil on that one is pretty small (at least on the pocket model not sure about the teaching model) so the centering would become very critical. Also you would probably need a fairly long exposure or a very bright lightsource. These are some of the details that need to be thrashed into submission when you do projects like this. (jleb I know your undoubtedly better at this than I am)

Next we will look at the signals coming out of some ot these cameras and what we can do with them. Also if what you really want to do is have a plot of the spectrum, rather than reinventing a very old wheel you would be better served by studying the Ocean Optics website from end to end. Then buy some of their scratch and dent fibers. and buy a spectrometer on ebay. Their software is free and very good. You can at the click of a mouse switch between photometric and radiometric (RLE) as mentioned in the paper that Winstone cited. and they would be more accurate and easier to calibrate. Might cost a bit more but would save alot of time.
Anybody out there?? Is this thing on??

[jleb]

I have had horrible luck with the opl teaching spect. I've tried using the scoptronix included lens in the set, and tried w/ out the lens and just the barrel onto the sensor... I just can't seem to get the focal length right and my light table isn't done yet to check that.. So if there is any wisdom floating around on how to get that set up, i'm all ears...

The second problem i'm having with that is when I do manage to get a spectrum sort of.. the red is bloomed and the other sides are variable.. so I don't get a uniform light intensity across the dispersion of the scope.. I'm thinking this may have something to do with either camera post processing or color filter masks overlaying the ccd sensor.. Not enough tek data in the instruction manual to dig that out..so not sure.. I use a canon digital rebel for this work.. it has around 7 mpixel element as the ccd sensor.. so would love some additional info if anyone has been successful with this..

I'll just roll on the floor if that cheap video cam that came with my phase contrast bio scope works better.. i'm gonna see if i can get that on it in a few days..

[G4Lab]

Well you certainly have the suspects identified. All that post processing even on a ccd video camera could be causing the headaches. You probably need to get the amount of light coming in right in the center of its range.

Use a black and white camera that you can buy at sams club for $50. Or a newvicon tube camera. You can just look at the video on your oscilloscope.

The red may be blooming because of using an incandescent light source.
Try a white LED or a xenon arc lamp. You know all this.

[winstone]

Well here goes,
This is not a project for the faint hearted or those who want a turn key product. It was a result of an accident and a failure to sleep. It was an EUREKA moment. It works for me, but I can not guarantee that it will work for you. Maybe it will. I will share plans for the unit if you guys who
build the unit agree to share your data with Bill Wise. He is exceted about having live pictures of collected gemstones.
I took a Kids camera with a tiny ccd, an OPL hand held spectrascope, and the camera's original software to produce what is amazing results for field gemologist. The entire project cost me less than $100. Add to it the freebie program from Ocean Optics and you will have a simple, yet reliable photospectrometer. What is lacking is feedback from other gemologists.
Some of our mad group have taken the idea and with a video cam made a live photospectrometer for desk top and lap top uses. I have made spectras of my gemstones. Feed back and R&D of participants is vital for the group, because we learn, prefect, and grow, with the imput of many minds. All of the items are found items, nothing is proprietory. So to get away from being an assembler, fixit, or warrantor of the uses,
I only wanted to know if it worked.
Unfortunately, the 9volt camera is no longer made. But there is a website for past owners. The camera can be found on EBAY for under $20.
comes with USB cable, works only with Windows, has CD of program, an album, and ability to take pictures in two formats, 640x420 and 320 x 210
color jpegs. The camera can be upgraded with a scans disk to take over
300 larger pictures and over 700 small pictures or spectras. The camera is a kids camera that easily can be adapted to accept the OPL. It also sports a built in flash, timer, and has some controls like turn off flash, and downloads. Pictures are digital and instant, but there is no viewer on the back of the camera.
The Images that I get are wonderful, because of the simplicity of the camera. fixed focus, and the fact that I can pan the spectra to see what the camera sees beyond the spectral range of the human eye.
The ccd is tiny only about 6mm x 3mm total. Powered by a common 9 volt battery that lasts for weeks. I read data on the ccd and it can "see
much more than we do as humans" and the computer can process images that would ordinarily be invisible to the naked eye using the same OPL
spectrascope. The price for making a camera that is only functional in the VIS wave area of the spectra would be too costly. The program and the circuit board helps to narrow the range of what is seen and not seen.
I had to modify the camera to add the OPL hand held spectrascope. Also, some friends want me to make an external attachment for their digital cameras, but that takes the fun out of using a simple camera to get
professional results. I include spectra prints on my appraisals. This is also for my workproduct.
Have I peaked your interest?
There is more, first I want to see if there is interest. If not this mad gemologist will content himself with more tests of gems in my study...
Winstone

[BillA]

I'll bite
what is the camera and website ?
the OPL hand held spectrascope would be Dr. William Hanneman's ?
the software "OOIBase32™ Spectrometer Operating Software" ?

Bill

[winstone]

Bill,
Even if we are the only ones on this website taking the dare, and in the spirit of this website, we together can enrich Bill Wise's program. I had hoped for more, but one other kindered soul will do. After all it is a beginning. The camera is the JamCam.
There are three ways to modify this little powerhouse of a camera.

a] Bob Hord GG, who was President of the North Texas GIA alumni came up with a way to use the camera to take macro pictures of gemstones in color. He used the camera and a JEWELER'S LOUPE duct taped to the front.
His pictures are wonderful and clean. I will set up a site for you guys to see his work.

b] Winstone, that's Alan Winston Smith GG, took the camera apart and carefully removed the fixed focus lens, I placed an OPL spectrascope in the hole of the plastic front after careful filing to make the hole fit the diameter of the OPL small hand held.
As the ccd is so small the resultant image focuses onto the ccd. Also I use a bathroom black rubber washer that fits over the OPL to keep out ambient lights. The software is loaded and the USB goes to the computer
It takes some adjusting, but the spectra hits the ccd and I get a color
spectra of the item that I am examining.
I had an earlier spectrophotometer that has a digital readout, that was a combination of parts, duct tape, prism spectrascope, and stand with halogen, but due to the heat, bulk, and weight, thought it would be neat if I could simplify the project down to a kids camera modified to do similar
tests. Also, I wanted the kids camera to be able to repeat tests on a simpler scale from those pieces of equipment that cost thousands of dollars more. Good science is repeatable science and should be valid even with simple tools all in the spirit of inventors fun. Could it be done?

c] My latest project is to combine a picture of the gem as well as have a digital readout, and color spectra all in the same picture frame with a ocean optic graph... super cool.....

I have a student who is an engineer and interested in learning gemology, He is working on the idea in C or part three, a lot of math,
programming etc. we will present our finding on this project later. back to
the cheapie because if the project is simple, then more people can add to the database and we can take something others considered trash and make treasure that benefits all of us. Wow a super idea.... or is it? Anyway for those who have Macs, I do not know how to make it work for them. Unless Hord's second idea of attaching it to a Video cam would work for both Windows and Mac? Ideas, results and spinoffs.....

PAUSE HERE ---- QUIET REVERANCE -----

Prayer to

OUR GREAT AND GOOD WEB MISTRESS-PROTECTOR A FTP SITE WITH PASSWORD FOR UPLOADED DATA THAT CAN BE SHARED......... COMES NOW, HER MOST LOW SERVANT.....Winstone

BANTER CONTINUES ----- My logic....

If our leader and protector for this website could set up a FTP site for us to upload scientific papers and plans for projects then it would be a great way to share data with everyone..... Winstone

[winstone]

A note to the reader from Winstone,
If you read the upper posts, they are scholarly and correct. The ccd that is being used is large and the OPL is small, it needs to be adjusted to make it work.
My solution is different, If the ccd is too large for the OPL, then find a small ccd that will work, small is good, small is cheaper, and the hunt is fun. Make it a game. Like an Easter Egg hunt, or treasure hunt, can we find a tiny ccd that is like the right size to take all of the image of the OPL..
I went to a Wolf Camera clearance store on Harry Hines, in Dallas, Texas and found a box of Jamcam cameras. I tried one, it seemed to work so with a few bucks bought a few more. Later I found new models on Ebay some cheaper some more. A good price is about $12 for a new camera, software, cables, I will take a picture of the box so that you can
see what a setup looks like.
I also wanted a camera that had a simple battery that is found anywhere. 9volt was my find. Also, it should have a flash, but have controls to turn it off, fixed focus, and a tiny ccd. A chip to upgrade, and
be rugged.
The goal is to have fun with the hunt, but the serious side was to get live spectras of my stones with a note of where they were from so that I could share them with Bill Wise. I have been corresponding with him for over a year. I told him that I wanted feed back, he directed me to this site, at gemologyonline.com. What a find! I am awed. Yet, my desire is still to share and experiment. I love the micro world of inclusions and wonders found in gemstones. We see things that exist in a micro world
we can hold in our hands. I sell included stones with especially nice structures to wealthy clients who also have discovered the tiny world of
inner gemstone structures. It has been my passion for over 40 year since I got my degree in gemological illustration from the University of Texas at Austin, in 1967. I know that there is so much to see, and enjoy. A universe in the palm of your hand..... awesome..... Winstone

[BillA]

ok, I now own a jamcam 3.0
bring on the photos

Bill

[winstone]

For over a year, I had spent a lot of time trying to make the Jamcam work with Mac. I am still baffled. The program is designed for windows. To calibrate the unit, I use different lights in my shop. Also it is important to have a fresh 9 volt battery. The next part is to carefully focus the OPL to the ccd. There are two ways to download information to the computer. One is to use the USB port and the other is to attach via a serial port. I dug out my modified camera and am running the basic known tests, getting it into focus, and will be showing some basic spectras. The next phase is to focus these images to get good results. Note in the Defraction grading spectra the colors are equal to each other. I will need to know how to down load pictures to this site, so that others can comment, and start their own albums of spectras. Winstone

[Julie Gowans-Poli]

Winstone, you can upload for free to sites like IMAGESHACK who then give you a choice of code to copy and paste here. Choose the "thumbnails for forums" code, and just paste it directly here.

[winstone]

Thanks for the tip. Oh there one thing that owners of models of the OPL hand held spectroscope should check. Hold the hand held in a third hand holder that has allagator clips and in a dark room see if your model has a lens in the eye piece or a piece of glass. This is VERY IMPORTANT. Place a sheet of wax paper, or translucent tracing paper, or frosted piece of glass, or a plastic cup bottom near the eye piece. If the spectrum from the sole light in the room makes a sharp spectra on this surface then your OPL has a lens in the eye piece. Most of the modern OPL do not have lenses. Our original design was copied from observing the human eye.
As most people have lenses in their eyes that focus light to their retinas, so too the spectra made with the refractive grading OPL needs to be focused onto the ccd of the JamCam, which is like a cameras retina.
Small lenses are easy to find, in small telescopes, some kids microscope oculars, or as mini magnifiers, or old camera parts, or you might even use the original lens from the camera to focus the image to the ccd. Hope that this tip helps. I have OPLs with lenses and without.
anyway, this idea came to me when I was helping my nephew build a unit and he had difficulty getting it to get in focus....... Winstone

[G4Lab]

After a little hiatus I am goaded into making another entry by our new member Brian who actually describes himself as a spectroscopist. Welcome!

We discussed the hand spectroscopes that are available and lighting and mounting and coupling scope and camera. Winstone mentioned using a JamCam. I think he is using JamCam 1.0 which seems to have been b/w
which is what we want in order to avoid all the complexities of the Bayer mosaic pattern which has double the number of green pixels. From what I can tell the JamCam 2.0 and 3.0 were color units, not what we want for this. Jam Cam went out of business in 2001
I have requested info on some webcams that may be B/W. We will prefer cameras without an infrared filter which may point us towards security cameras which MAY be black and white and if designed to "see in the dark"
will not have an IR filter installed. All the sensors are made with silicon however and silicon runs out of sensitivity at about 1100nm. The glasses in our lightsource and hand spec will run out of transmissibility at about 350 nm so this is the range we can cover. Some spectroscopes may cut off right at 800 though in terms of aperature and field number of their eyepiece since that is all they are intended to cover.

So we are going to try to find a suitable black and white camera. A webcam , a security cam or possibly a microscope cam or machine vision cam. In machine vision they are often concerned with dimensional precision and can do better with black and white than with color once agin because of the Bayer pattern. Machine vision cameras are usually black and white CCD cameras. Microscope cameras can be CCDs CMOS or have video tubes in them. These are one inch in diameter and can resolve 1000 pixels if you have a frame grabber that is that good.

A frame grabber??!! What is a frame grabber?? Its the thing that takes what the camera sees and makes it into a format the computer can eat digestibly. Web cams have a frame grabber built in as does the jamcam.
This is their big advantage. Everybody else has a video output which then has to be captured in a format that your software can digest. Preferably unmassaged from a mathematical point of view. That means .tiff or .raw


I have some experience with such frame grabbers from microscopy but they are neither cheap nor easily available. the trick will be to find one like winstones jamcam that is B/w and USB compatible and can save a still image in a format that can be looked at by the software that is going to make our wiggly line.

Maybe we should all just use Ocean Optics spectrometers like Marty Haske does and like Brian does and like Bear Williams does.

There are a couple of cameras I know about that would work well.
One is the Hitachi KP M1 I saw one on ebay recently and was outbid on it.
It went for like $60 Runs on 12volts, has a removeable IR filter and has pretty good resolution and a 2/3 in ccd chip.
Somebody mentioned Pulnix cameras on another thread and they are well known. There is also a company called Dage-Mti that has a bunch of monochrome cameras on their website including some discontinued models that they are offering cheep. And I happen to know they will take EVEN LESS

Time for bed. Nite All!