Photonics West 2025

[Din]

Here are the papers being presented this year at the Photonics West Practical Holography session: https://spie.org/PW25O/conferencedetail ... holography

This year, it's chaired by Hiroshi, with whom some of us had many conversations over the years, and Pierre-Alexandre Blanche, with whom I've worked while consulting with the University of Arizona.

I've found it particularly interesting that Bayfol is manufacturing IR sensitive holographic material. There's been a great deal of interest in eye scanning holographically with IR, but unfortunately, there was no IR sensitive holographic material. In fact, I was asked to come up with an IR sensitive material myself: https://spie.org/photonics-west/present ... m/13390-26

Petr, you mkight be interested in this: https://spie.org/photonics-west/present ... hy/13390-9

[lobaz]

Thanks, Dinesh, I'll check it.
Difficult to guess what is the novelty in the paper you have linked. Using line segments instead of points is an old idea, see e.g.

Computer-generated holograms of three-dimensional objects composed of line segments
Ch. Frere, D. Lelleberg, and O. Bryngdahl
J. Opt. Soc. Am. A, Vol. 3, No. 5/May 1986

Computer generated holograms: cylindrical, conical, and helical waves
Detlef Leseberg
Applied Optics, Vol. 26, Issue 20, pp. 4385-4390 (1987)

Holographic Imaging of Lines: a Texture Based Approach
Alf Ritter, Oliver Deussen, Hubert Wagener, Thomas Strothotte
IV '97 Proceedings of the IEEE Conference on Information Visualisation

[Joe Farina]

Though I won't be in San Francisco this weekend, I received a note from Vitali Kosenko of Laserand Inc. regarding the high-power 640nm lasers. (I had inquired about the pricing of these lasers.):

"And regarding the SPIE PW 2025.
You can suggest your colleagues visiting us at the booth #5017
You will meet Jack Ng here who will be happy to answer your questions.
You can also reference to our brief conversation with me over the email.
I will be browsing around, but Jack will be at the booth all the time."

and in another email:

"2W model availability.
Not in the near term. Depends on when the customer wants the laser?
As the customer said himself, it is unprecedented and highest in the industry, we need to do a lot of testing for performance guarantee. So we don’t want to over promise. But welcome inquiries if they have money to spend, we will build it."

They said the maximum power available in the near term was 1.5W rather than 2W: "We had a review about our product specs at the start of the year, we have changed the 640nm power to 1.5W max now."

[Din]

Not uncommon to be asked to go to their booth. There, you'll be met with salespeople (they rarely seem to have technical people manning the booth) who'll extract your data, try to make appointments for their sales people to talk to your sales people, and find out how you can be useful to them, including, as in this case, if you'll finance their product development.

One time, I was interested in a laser around 405nm for mass production holography. I was invited to go to their booth, where I met with a sales person who wanted to talk to our sales people. I told them that Triple Take Holographics was just me and my wife and we had no salespeople. They must have looked at our web page, where we listed our clients, including the Navy, Microsoft and several other high profile clients, mostly having their own holo labs. Next thing I know, the sales person shows up at Triple Take in San Diego, and asks us if we would promote their laser to our clients!

[Din]

Joy says that the laser is from Skylark ( https://www.skylarklasers.com/ ) in Scotland. Laserand are a reseller. Skylark does not have these lasers on hand, they'll build one should you want it. She says the cost is north of $30,000.

She has to source materials, including lasers, for her projects, so she's pretty familiar with optics sources.

[Joe Farina]

Thanks Din and Joy. That's interesting. The nearest equivalent at 640nm, as far as I know, is the 300mW Cobolt Bolero, which is over $20,000. The problem with these expensive lasers is that, after the warranty expires (maybe 2 years at most), any customer support would be an open question. I'm not willing to take the risk, especially when surplus lasers are easily available. (I recently bought a 1W Coherent Genesis 532nm on eBay for $1,350, and it had less than 100 hours on it.)

It's too bad higher-power red lasers for holography are so expensive. It puts a damper on the development of color holography. The Skylark lasers (thanks for the link by the way) are interesting. If the cost isn't far in excess of $30,000 for 1.5W, that doesn't sound bad in comparison to Cobolt Bolero at 300mW for ~$20,000 (not sure how much over $20,000 this laser is). Five times the power. But these new lasers are for someone else, not me.

[Valery]

Hi . Has anyone used MDL-C-660-100 , MDL-C-660-120. The price of these lasers is not very much.
Please let me know if anyone has used these Chinese lasers.

[Joe Farina]

Haven't used it, but at least they say it's good for holography:

https://www.cnilaser.com/PDF/MDL-C-660.pdf

120mW is quite good. I wonder what the practical difference is between 640 and 660nm for color holography. According to Kaveh's paper (which is the one that makes most sense to me), the ideal red wavelength is closer to 610nm (I don't remember exactly, but this is close). Do you happen to know the approximate price of this laser? Thanks Valery.

A thread on color holography wavelengths: https://www.holographyforum.org/forum/v ... php?t=3567

[Din]

Reading back on those old posts, I notice I brought up the idea of colour holograms working in either a subtractive or additive scheme. It's commonly believed that colour in holography is based on the additive RGB scheme. I never thought this was completely true. I wish I'd done more work on the additive/subtractive color schemes in color holography. We made a transmissive colour hologram - open aperture, not rainbow - using a single laser in transmissive mode using dichroics (https://opg.optica.org/abstract.cfm?uri=DH-2014-DTh3B.2 ), and I'm pretty sure that dichroics operate on a CMYK space, and so would have been a subtractive colour scheme.

[lobaz]

I wonder what the practical difference is between 640 and 660nm for color holography. According to Kaveh's paper (which is the one that makes most sense to me), the ideal red wavelength is closer to 610nm

One very practical difference is luminous efficacy of those wavelengths, i.e., how bright they look like. If we set luminous efficacy of 555 nm as 100%, then luminous efficacies of 610, 640 and 660 nm are 50%, 17% and 6%. In short, a bright red object would appear much dimmer with 660 nm than with 610 nm.
Note that those per cent numbers do not exactly describe perception, they just tell CIE Y value. A more appropriate description would be using L* value of CIELAB color space. For 555, 610, 640 and 660 nm, the L* values are 100, 76, 49 and 30. So, quite a significant drop from 640 to 660 (or even from 610).

Also note that most LED white sources contain smaller amount of 660 than of 640 nm, so red would be even dimmer thanks to light source. However, this can be easily compensated by tweaking reconstruction light color.