I work in optics at my day job. For me, one of my secret pleasures of optics is learning the ancient technologies, techniques, and measurements, that remain viable even in modern times. It's a pleasurable counterbalance to the "new framework of the month" syndrome, and helps keep me sane.
Mirror grinding
61–66 of 66 posts
Re: Mirror grinding
#62My parents run a business making telescope mirrors, and I grew up around this exact process. Measurement is the biggest difference between this and what they do. Take a look at https://en.wikipedia.org/wiki/Interferometry#Engineering_and... if you want to know more about how it's done in industry. The best metaphor I got from them about how precise a shape they make in glass is that if you took a typical 1 meter mirr…
It's interesting that you mention measurement. I've been involved in a number of exercises to source optical components in China, and have learned to judge a vendor by what measurements they're capable of.
I think there's an analogue to test-driven development in software. Many designs that you look at make no sense until you understand what can be measured readily and what can't, while making the parts and assembling them into a system.
Re: Mirror grinding
#63Earlier quoted context omitted.
The approach most advanced people use now is deformable mirrors. They work in concert with a laser that emits from the detector, bounces off the atmosphere, and produces a real time map for the deformation (you have to solve an inverse problem here IIRC). You can also use a wavefront sensor. For small problems, you can just buy these things off the shelf: https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=32..…
The history behind wavefront sensors is pretty fascinating. It was developed in the 60's by Hartmann, in order to better image satellites from earth, and then largely ignored by the astronomy community, even though he presented it to them, until the 80's. I can't find the original paper that I read, but here's a bit of history [1]. [1] https://pdfs.semanticscholar.org/d1ed/a97dd2cf70f54f24b85abc...
WHen I started grad school in Biophysics (1995), a microscope professor mentioned adaptive optics and asked the incoming students if they thought similar processes could be done in microscopy. If you said yes, he let you join his lab (they were already working on this).
Re: Mirror grinding
#64Earlier quoted context omitted.
The history behind wavefront sensors is pretty fascinating. It was developed in the 60's by Hartmann, in order to better image satellites from earth, and then largely ignored by the astronomy community, even though he presented it to them, until the 80's. I can't find the original paper that I read, but here's a bit of history [1]. [1] https://pdfs.semanticscholar.org/d1ed/a97dd2cf70f54f24b85abc...
WHen I started grad school in Biophysics (1995), a microscope professor mentioned adaptive optics and asked the incoming students if they thought similar processes could be done in microscopy. If you said yes, he let you join his lab (they were already working on this).
I wonder if it would be possible to make a deformable mirror using a combination of liquid mercury chemically bonded with a ferromagnetic metal (if mercury isn't already magnetic). Then theoretically, you could use an electric current in a coil to shape the liquid into a precise shape.
Re: Mirror grinding
#65Earlier quoted context omitted.
WHen I started grad school in Biophysics (1995), a microscope professor mentioned adaptive optics and asked the incoming students if they thought similar processes could be done in microscopy. If you said yes, he let you join his lab (they were already working on this).
I wonder if it would be possible to make a deformable mirror using a combination of liquid mercury chemically bonded with a ferromagnetic metal (if mercury isn't already magnetic). Then theoretically, you could use an electric current in a coil to shape the liquid into a precise shape.
Maybe? I wouldn't touch mercury for any reason, though.
Re: Mirror grinding
#66Earlier quoted context omitted.
The history behind wavefront sensors is pretty fascinating. It was developed in the 60's by Hartmann, in order to better image satellites from earth, and then largely ignored by the astronomy community, even though he presented it to them, until the 80's. I can't find the original paper that I read, but here's a bit of history [1]. [1] https://pdfs.semanticscholar.org/d1ed/a97dd2cf70f54f24b85abc...
WHen I started grad school in Biophysics (1995), a microscope professor mentioned adaptive optics and asked the incoming students if they thought similar processes could be done in microscopy. If you said yes, he let you join his lab (they were already working on this).
Oh interesting!
Were they working with some sort of fluid interface? Maybe layered liquids, or fluids that you don't want to dip an objective lens into? Or maybe temperature gradients?