#1046

[@JamesChurchill]

Given that wedge filters are so rare, wouldn't it be more accurate to call a spectrometer a "poor man's wedge filter" rather than the other way around? :D

[@Ni5ei]

Wow, that long wedge filter is awesome. It's perfect for showing the complete spectrum. Would love to have one.

[@roboanalogtom]

What a great video! I use a spectrometer with the work I do in horticulture light. As a tip for everyone, you can buy 400-700nm very sharp bandpass filters for about $20 on Amazon. My quantum light sensor uses one as well as a silicon photodiode flattening response filter. (Most?) lux meters use a simple plastic green broader short pass filter and then rely on the natural spectral response of the photodiode to approximate lux which is why they are much cheaper to make.

[@IMSAIGuy]

If you only want to measure LUX, you can get high end photometric sensors, that are photodiodes with expensive glass colored filters to fit the photometric curve much better than the cheap lux meters. UDT used to make them but they may be part of gamma scientific now.

[@roboanalogtom]

@@IMSAIGuy Oh that's going to be pricey! My USB SQ-520 quantum light sensor from Apogee was $500 and I thought that was a bargain.

[@mr1enrollment]

cool, thanks for introducing the wedge y!

[@multiforc271]

loved the video, learned new things, specially the wedge filter. also i am super interested in making some diy and experiments that i can do at home, it is always nice to have fancy equipment, but the joy of making somethin from scratch is much much more. if you have time, please make some videos about the experiments that we can perform at home, for example making a mirors, filters and etc.

[@lmamakos]

I do astrophotograhy as (yet another expensive) hobby, and one of the filters in my camera's filter wheel is a narrow band Hydrogen-alpha emission line filter. It's got a 13nm wide bandpass at a 656nm wavelength (red). Just looking at it, it just appears to be a mirror... an expensive 35mm diameter filter that just lets only a few photons through. And of course, RGB dichroic filters that don't look like any of those colors from the front.. Neat stuff!

[@robballantyne3]

Fascinating. I hadn't watched any of your optical videos until now. The picture you drew of the dichroic filter reminded me of the math of beamformering. Is it yet another application of beamforming?

[@IMSAIGuy]

the math will look very familiar

[@JamesBailey123]

Loved the video, never heard of a wedge filter and can't even find a reference on rpphotonics. Where can I go to learn more about or even purchase one? Would love a follow up video explaining where the passed / reflected wavelengths go and how that relates to the micro bumps

[@IMSAIGuy]

www.edmundoptics.com/f/linear-variable-bandpass-filters-5fd8f505/14865/

[@JamesBailey123]

@@IMSAIGuy ohh they're the linear variable filters, those I've heard about, just 'wedge filter' only brought up ordinary glass prisms. I assumed there was just a different thickness to the multiple interfetence layers not 3D structures doing the filtering. Also didn't realise they looked so 'silver' if not back illuminated (that website and all others they might as well be absorptive filters for how they appear, no dichroic colour shift, no broadband reflections).

[@IMSAIGuy]

@@JamesBailey123 there is no 3d structure, just layer thickness changes in the bandpass thin film stack. they are dichroic. pass wavelength goes through, stop wavelengths are reflected, no absorption

[@JamesBailey123]

@@IMSAIGuy thank you for the explanation, rewatched your video more attentively ane my mixup was not realising the 'bumps' you drew were of course wavelength ranges relating to the dichroic filter layer thicknesses, very clear just my fuzzy listening. Thank you for the follow up.

[@itsevilbert]

As a young kid I used to look at the thin film of oil on water and wonder if there was any way that could do anything useful, now I know - Thanks.

[@luomoalto]

I’ve seen them before. 😁 I used something similar, a linear high pass filter, to sort orders in wide range grating spectrometers (190-1000nm)

[@jafinch78]

Wow, totally awesome! I've never seen that long a wedge filter or even such a great video detailing in general a range of filters. Very excellent! Wondering theoretically with like say a 4K webcam lens... what's the highest resolution of a theoretical wedge filter spectrometer in the ideal optical train designed for? I was thinking that last lens was like a neutral density filter. Neat, I've been wanting to make a webcam spectrometer using like BluRay disc section as a diffraction grating on a hard drive actuator to sweep like a dispersive instrument though with that magnetic bearing and a nice Apple CD/DVD drive sled for the slit width control for the collimator(s). I so have all the parts... just not the best environment conducive for many of my projects. Thanks for sharing! Really neat... and times well with Les' Lab DIY integrating sphere video.

[@jafinch78]

Amazing also how many are not aware of the THz and down the range optical methods & parts that are like what the human senses detect & perceive. Neat and awesome to watch! Maybe you can do a homebrew interferometer spectrometer from like common parts? I'd like to try that out one of these days as well and have been saving parts to play with after doing some theory for feasibility.

[@jafinch78]

Polarity would be neat to see also... I'd like to add that dimension of information to the webcam spectrometer as well. Like the circular dichroism aspect.

[@IMSAIGuy]

have you seen this: kzbin.info/www/bejne/fYmnapZribZpgtU

[@johnjohn-ed9qt]

I am curious where in the system the metal-screen attenuator went to minimize artifacts downstream in an imaging application, such as a microscope illuminator or a telecentric illuminator for an optical comparator. I would presume this was in a surface illuminator or a fibre optic illumination source?

[@IMSAIGuy]

it was at the aperture stop of an illuminator.

[@byronwatkins2565]

Yellow is a SHORTER wavelength than red, blue is a SHORTER wavelength than green, and violet is a SHORTER wavelength than blue. The wedge filter extends into the NIR and NUV at the ends that we cannot see but, yet, are useful in applications with electronic sensors.

[@ThinklikeTesla]

I keep thinking about designing something like one of those 328 universal component testers that are all over the Chinese markets for like $7, except also with an optical channel. Using a fancy filter would be cool, but probably not good for manufacturing. With a cluster of maybe 5ish LEDs of different wavelengths including IR, and 5ish detectors of similar wavelengths, you could run an unknown component through a bunch of different paces and help sort out the junk drawer full of unknown optical components that so many of us have. (Or is it just me?) Photodiode at 940nm? Check. Phototransistor for visible light? Check. Etc.

[@IMSAIGuy]

you might look at this one: www.maximintegrated.com/en/design/technical-documents/app-notes/5/5410.html I was hired as a consultant on that project.

[@romeugabriel6978]

Which is the Size of the bandpass wedge filter?

[@romeugabriel6978]

How do you get a dispersive wedge filter? I known that it is rare, but I really like to get a one

[@IMSAIGuy]

you can try edmunds www.edmundoptics.com/f/linear-variable-bandpass-filters-5fd8f505/14865/

[@R50_J0]

At 7:00 you didn't differentiate between mirrors used in an optical lab and common consumer mirrors. Lay viewers could think all mirrors are the thin film type.

[@IMSAIGuy]

Oh no!!

[@mariomionskowski6223]

Thank you for the information, i have that never seen bevor, but the basics of that i had that in school, Wilhelm Herschel from hanover.

[@ChrisSmith-tc4df]

What about using optical linear polarizers at variable angular offsets? There would be the >50% transmission loss on an unpolarized light source.

[@IMSAIGuy]

I don't understand the question

[@fsphil]

I believe the New Horizons spacecraft to Pluto carried one of these, in the LEISA instrument.

[@pbaemedan]

Snell law is amazing

[@SixWildKids]

Is Obsidian equivalent to black glass?

[@IMSAIGuy]

it is mostly glass.

[@ChrisSmith-tc4df]

Edmund Optics has a 6cm Linear Variable Dichroic Filter for only $1530 😲

[@IMSAIGuy]

yep, they ain't cheap

[@edieharo4186]

Really interesting, Thanks

[@Masirah1]

Notes stored in your iphone appeared on the video.

[@IMSAIGuy]

I know. Maybe it's a clue. Maybe it's nothing

[@romeugabriel6978]

IT IS VERY EXPENSIVE!!!

[@nickcaruso]

and there's no single frequency of light which produces the sensory impression of pink :-)

[@IMSAIGuy]

That statement is also true for 99.99999999% of the other colors too. monochromatic colors are quite rare.

[@nickcaruso]

@@IMSAIGuy interesting point... huh.

[@Leonardo-ql1qu]

This is so frustrating! Why don't you prepare your video's better and choose another filming angle? All the drawings you make are obscured by your hand doing the drawing. Like talking to a camera for half an hour with a face mask on. Very distracting and sloppy!

[@IMSAIGuy]

go somewhere else if you expect polished videos. That is not what this channel is about

[@Leonardo-ql1qu]

@@IMSAIGuy I will! You can't handle criticism very well, can you? And you know what's funny? For the next video you will surely choose a better angle. But you don't need to thank me for it. Good luck.