Re: [time-nuts] ?==?utf-8?q? a newbie question: where can I purchase 794.7 nm VCSEL for building CPT rubidium clock?
On Mon, 11 Jun 2018 06:53:49 +0200 Magnus Danielson wrote: > One might then ask what the availability and pricetag is for nonlinear > chrystal needed for frequency doubling. It cannot be too much, given the fact that these are used in green laser pointers. Though, I have to say I am astonished how expensive those VCSEL are. I would have guessed they are below $100/pcs, given that "normal" laser diodes are usually in the order of $10-$20. Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] where can I purchase 794.7 nm VCSEL for building CPT rubidium clock?
Well, no. Green laser pointers convert a rather high power 800 nm laser to 1600 nm in one crystal then divide it to 533 nm in another one. The physics and manufacturing of them is best described as black magic. They are cheap because China developed the process to grow the crystals in bulk and crank out zillions of them for consumer products. I suspect that a 1600-ish nm to 800-ish nm converter is not a stock consumer-quantity device and will cost a pretty penny or two... like a red/IR laser diode can be had for 50 cents and a telecom VCSEL diode can be $500. -- > It cannot be too much, given the fact that these are used in green laser pointers. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] ?==?utf-8?q? a newbie question: where can I purchase 794.7 nm VCSEL for building CPT rubidium clock?
The output wavelength of a VCSEL is current and temperature dependent so using a low noise current source and regulating the chip temperature is usually necessary to allow locking to an atomic transition. Most VCSELS for such applications include a peltier module within the housing. Bruce > On 11 June 2018 at 19:26 Attila Kinali wrote: > > > On Mon, 11 Jun 2018 06:53:49 +0200 > Magnus Danielson wrote: > > > One might then ask what the availability and pricetag is for nonlinear > > chrystal needed for frequency doubling. > > It cannot be too much, given the fact that these are used in > green laser pointers. > > Though, I have to say I am astonished how expensive those VCSEL are. > I would have guessed they are below $100/pcs, given that "normal" > laser diodes are usually in the order of $10-$20. > > > Attila Kinali > -- > It is upon moral qualities that a society is ultimately founded. All > the prosperity and technological sophistication in the world is of no > use without that foundation. > -- Miss Matheson, The Diamond Age, Neil Stephenson > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] a newbie question: where can I purchase 794.7 nm VCSEL for building CPT rubidium clock?
On Sat, 9 Jun 2018 23:28:29 +0800 mimitech mimitech wrote: > Just do a little bit research on 1560nm telecom laser transceiver. The > closest wavelength is 1560.61nm (DWDM channel 21) as defined by ITU. > Usually telecom laser transceiver module uses DFB (distributed feedback) > type laser diode instead of VCSEL laser. However, the DFB LD should be > capable of direct modulation, so there maybe not much difference with VCSEL > in terms of usage. For the modulation bandwidth, I guess a 2.5Gbps module > should be OK for 1.71GHz analog modulation. A 2.5Gbps module should be good even for 3.4GHz modulation. The 3dB frequency of should be higher than the baud rate used. Besides, even if the 3dB frequency is below 3.4GHz, that does not matter, it just means that your sidebands will be damped (second order low pass, IIRC), but you don't need that much power anyways. > So, imagine I modulated 1.71GHz microwave signal onto 1560nm laser wave, > then used a KPT non-linear optical crystal to double the frequency, > hopefully I could get 780nm laser with +/-3.42GHz sideband spectrum, that > should be suitable to shine on a Rubidium vapor cell and trigger CPT > effect. I don't know if I understand this process correctly, many details > must be missed. Using a non-linear element will give you lots of intermodulation products. Ie, your sidebands will be +/-1.71GHz, +/-3.42GHz, +/-6.84GHz,... So you will have to be a bit carefull with the laser tuning in order to get the right harmonics. An alternative approach would be to use an EOM after the doubler to get the sidebands. These have bandwidths in the order of 10-20GHz, so applying 3.42GHz shouldn't be a problem. BTW: a lot of the frequency doubler architectures for high stability lasers use resonant cavities, to increase efficiency and decrease noise. You will either have to tune the free spectral range of the cavity to a divisor of 6.84GHz or use a non-resonant one. > Another question is, after passing through the KPT doubler crystal, whether > the light remains single mode and linear polarization mode or not? If > someone could provide any relevant information and suggestion, thanks very > much. If I understood the optical process correctly (disclaimer: I'm not a physicst and have never worked with optical systems), then the multiple modes are a problem of the laser source, not of the doubler. As multi-modes are a problem for high speed communication, I expect telecom lasers to be quite clean. You will have to ensure that you are not operating it close to a mode jump, though. A side note on the doubler approach: The group at UniNE around Gaetano Mileti and Christoph Affolderbach focuses only on double-resonant Rb standards. That means they do not modulate the laser. As they have gotten the whole standard to the SNR limit, they are now focusing on getting the shifts due to laser (frequency and intensity shift) and cavity (low Q cavity to avoid pulling) down. The current state of affairs is quite nicely documented in their two papers at 8FSM[1,2,3]. Attila Kinali [1] Proceedings of the 8th Symposium on Frequency Standards and Metrology http://conferenceseries.iop.org/conferenceseries/issue/1742-6596/723/1 [2] "High performance vapour-cell frequency standards", Gharavipour, Affolderbach, Kang, Bandi, Buret, Pellaton, Mileti, 2015 http://iopscience.iop.org/1742-6596/723/1/012006/pdf/1742-6596_723_1_012006.pdf [3] "Pulsed Optically Pumped Rb clock", Micalizio, Levi, Godone, Calosso, François, Boudot, Affolderbach, Kang, Gharavipour, Gruet and Mileti, 2015 http://iopscience.iop.org/1742-6596/723/1/012015/pdf/1742-6596_723_1_012015.pdf -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] where can I purchase 794.7 nm VCSEL for building CPT rubidium clock?
PPLN (Periodically poled lithium Niobate) is the frequency doubler of choice for such applications however it needs to operated in a temperature regulated oven. To achieve efficient frequency doubling the input light needs to remain in sync with the frequency doubled output light as they propagate through the frequency doubler. The frequency doubler Crystal optical dispersion and directional dependent propagation ensures that a crystal aligned for 164/532nm operation is unlikely to function effectively for 1680/890nm operation. PPLN however works well over a wide bandwidth. Bruce > On 11 June 2018 at 19:43 Mark Sims wrote: > > > Well, no. Green laser pointers convert a rather high power 800 nm laser to > 1600 nm in one crystal then divide it to 533 nm in another one. The physics > and manufacturing of them is best described as black magic. They are cheap > because China developed the process to grow the crystals in bulk and crank > out zillions of them for consumer products. > > I suspect that a 1600-ish nm to 800-ish nm converter is not a stock > consumer-quantity device and will cost a pretty penny or two... like a red/IR > laser diode can be had for 50 cents and a telecom VCSEL diode can be $500. > > -- > > > It cannot be too much, given the fact that these are used in > green laser pointers. > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Casio Wave Ceptor wrist watch - quick accuracy test
Hi! There seems to be some kind of comeback going on with 80's style digital watches. You may find replicas of some 80's models or even re-makes of the original models from original manufacturer. So I decided to get one. As a time-nut my primary goal was to have radio controlled 'atomic' model. So I ended up to Casio Wave Ceptor WV-59DE-1AVEF. There's many models available from basic digital models like this to very nice ones with with full titanium body (analog style). But because of the 80's is hot it had to be digital... Wave Ceptors suport all time signals formats (US, UK/German and Japan) and correct standard is automatically selected when home city is set. One of the first things to do was to test the accuracy with radio syncronization turned off. Correct time was fist set with DCF77. Then I switched off the synconization. After beign about three days off there was no significiant visible error on time. In the video we can see however about one frame error, which means about 40 milliseconds. Still that's pretty good result for wrist watch. Also, the syncronization will occur once per day when the reception is good. So the watch must be at least calibrated in the factory. Don't know if the watch performs any kind of self-calibration according to radio syncronization results, most likely not - but it would be technically possible. So far so good, it's accurate enough - at least as new. When syncronization is turned on, there should never be visible error on time. Here's my test video: https://www.youtube.com/watch?v=_A23buFeHd0 -- 73s! Esa OH4KJU ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] a newbie question: where can I purchase 794.7nm VCSEL for building CPT rubidium clock?
On Sat, 9 Jun 2018 16:54:15 +0800 mimitech mimitech wrote: > I prefer the 780/795nm VCSEL scheme for its simplicity. After some > searching, looks like the 780nm VCSELs are also not easy to source, > although other types of 780nm LD are common. Why are you focusing on VCSEL anyways? Standard laser diodes already have a modulation bandwidth that goes into several 100MHz, the better ones should give you 1-2GHz. With that, you should be within 6dB, maybe 10dB of the CW power. Given that you only need a few 10µW to 100µW of laser power, and that those diodes are in the 1-30mW range should give you enough margin. Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Raw phase data of super-5065
Ciao Luciano, On Fri, 8 Jun 2018 14:05:24 +0200 "tim...@timeok.it" wrote: >Here a ten days simultaneously run of the A and B version compared with my > HP Z3816A GPSDO. Thanks a lot! Unfortunately, I have no application that can read XPS files available. Can you send it as something more standard? Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Casio Wave Ceptor wrist watch - quick accuracy test
I bought a Casio 'atomic watch" about 3 months ago, one which uses the '3405' module. I've also been running checks with radio setting turned off, and mine is coming in at just under 1 sec per month, based on seeing how long it takes to drift one second. But I find that visual/aural coordination is a poor way to do business- if the error is near zero (or an integer number of seconds), my eye/ear/brain will shift to make it look like it's "right on" within a few seconds even if the initial look says it's a little bit off. I hadn't thought of the video approach- sure wish I had a means to record video and then view it frame by frame. Dana On Mon, Jun 11, 2018 at 3:20 AM, Esa Heikkinen wrote: > Hi! > > There seems to be some kind of comeback going on with 80's style digital > watches. You may find replicas of some 80's models or even re-makes of the > original models from original manufacturer. > > So I decided to get one. As a time-nut my primary goal was to have radio > controlled 'atomic' model. So I ended up to Casio Wave Ceptor > WV-59DE-1AVEF. There's many models available from basic digital models like > this to very nice ones with with full titanium body (analog style). But > because of the 80's is hot it had to be digital... > > Wave Ceptors suport all time signals formats (US, UK/German and Japan) and > correct standard is automatically selected when home city is set. > > One of the first things to do was to test the accuracy with radio > syncronization turned off. Correct time was fist set with DCF77. Then I > switched off the synconization. After beign about three days off there was > no significiant visible error on time. In the video we can see however > about one frame error, which means about 40 milliseconds. Still that's > pretty good result for wrist watch. Also, the syncronization will occur > once per day when the reception is good. > > So the watch must be at least calibrated in the factory. Don't know if the > watch performs any kind of self-calibration according to radio > syncronization results, most likely not - but it would be technically > possible. > > So far so good, it's accurate enough - at least as new. When > syncronization is turned on, there should never be visible error on time. > > Here's my test video: > https://www.youtube.com/watch?v=_A23buFeHd0 > > -- > 73s! > Esa > OH4KJU > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/m > ailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] where can I purchase 794.7 nm VCSEL for building CPT rubidium clock?
Mark's description about how (most) green laser pointers work is a bit in error, and is perhaps over-simplified- the reality is actually more fascinating yet: First a diode laser operating at around 808 or 809 nm is used to optically pump a solid state laser which generates light at 1064 nm. This light is then frequency doubled with an intra-cavity nonlinear element to produce the final output at 532 nm. For all this to work the optical elements must be critically aligned, and to me the most amazing thing about the low selling price is how this alignment is effected so cheaply. One of these units I've opened up has the doubler crystal held down by a lump of cement on one side- it looks for all the world like it must have pushed into alignment and "held" there while the cement was cured. Green pointers made in this way are characterized by quite good beam quality and very little wavelength spread from unit to unit. However, they are generally quite delicate and ruined by mechanical shock. Although not commonly known, at least one outfit (Z-Bolt) is now selling "direct diode" green pointers, where there is just one laser which emits directly in the green, at around 515-530 nm. These are much more robust, operate well over a wider temperature range, but have the usual poor beam quality (non-circular beam with some residual astigmatism) characteristic of diode lasers made with simple collimating optics. And, the output wavelength spread from unit to unit is quite large. Dana On Mon, Jun 11, 2018 at 2:43 AM, Mark Sims wrote: > Well, no. Green laser pointers convert a rather high power 800 nm laser > to 1600 nm in one crystal then divide it to 533 nm in another one. The > physics and manufacturing of them is best described as black magic. They > are cheap because China developed the process to grow the crystals in bulk > and crank out zillions of them for consumer products. > > I suspect that a 1600-ish nm to 800-ish nm converter is not a stock > consumer-quantity device and will cost a pretty penny or two... like a > red/IR laser diode can be had for 50 cents and a telecom VCSEL diode can be > $500. > > -- > > > It cannot be too much, given the fact that these are used in > green laser pointers. > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] where can I purchase 794.7 nm VCSEL for building CPT rubidium clock?
The better ones use optically contacted crystals to avoid browning of the adhesive due to the high power densities of the 1064nm laser required for efficient frequency doubling. Brue > On 11 June 2018 at 22:52 Dana Whitlow wrote: > > > Mark's description about how (most) green laser pointers work The better is a > bit in > error, and is perhaps > over-simplified- the reality is actually more fascinating yet: > > First a diode laser operating at around 808 or 809 nm is used to optically > pump a solid > state laser which generates light at 1064 nm. This light is then frequency > doubled with an > intra-cavity nonlinear element to produce the final output at 532 nm. > For all this to work > the optical elements must be critically aligned, and to me the most amazing > thing about > the low selling price is how this alignment is effected so cheaply. One of > these units I've > opened up has the doubler crystal held down by a lump of cement on one > side- it looks > for all the world like it must have pushed into alignment and "held" there > while the cement > was cured. Green pointers made in this way are characterized by quite good > beam quality > and very little wavelength spread from unit to unit. However, they are > generally quite > delicate and ruined by mechanical shock. > > Although not commonly known, at least one outfit (Z-Bolt) is now selling > "direct diode" > green pointers, where there is just one laser which emits directly in the > green, at around > 515-530 nm. These are much more robust, operate well over a wider > temperature range, > but have the usual poor beam quality (non-circular beam with some residual > astigmatism) > characteristic of diode lasers made with simple collimating optics. And, > the output > wavelength spread from unit to unit is quite large. > > Dana > > > On Mon, Jun 11, 2018 at 2:43 AM, Mark Sims wrote: > > > Well, no. Green laser pointers convert a rather high power 800 nm laser > > to 1600 nm in one crystal then divide it to 533 nm in another one. The > > physics and manufacturing of them is best described as black magic. They > > are cheap because China developed the process to grow the crystals in bulk > > and crank out zillions of them for consumer products. > > > > I suspect that a 1600-ish nm to 800-ish nm converter is not a stock > > consumer-quantity device and will cost a pretty penny or two... like a > > red/IR laser diode can be had for 50 cents and a telecom VCSEL diode can be > > $500. > > > > -- > > > > > It cannot be too much, given the fact that these are used in > > green laser pointers. > > ___ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > > mailman/listinfo/time-nuts > > and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] where can I purchase 794.7 nm VCSEL for building CPT rubidium clock?
I should have written more clearly- the adhesive in question was *not* in the optical path. As is usual, variations are possible, one supposedly being that the crystal that lases at 1064 nm is also doped with something to make it nonlinear (so I've read). I kind of have my doubts over this, however it seems like asking too much of a single substance to do "double" duty without some unwanted compromises. Dana On Mon, Jun 11, 2018 at 6:06 AM, Bruce Griffiths wrote: > The better ones use optically contacted crystals to avoid browning of the > adhesive due to the high power densities of the 1064nm laser required for > efficient frequency doubling. > > Brue > > On 11 June 2018 at 22:52 Dana Whitlow wrote: > > > > > > Mark's description about how (most) green laser pointers work The better > is a bit in > > error, and is perhaps > > over-simplified- the reality is actually more fascinating yet: > > > > First a diode laser operating at around 808 or 809 nm is used to > optically > > pump a solid > > state laser which generates light at 1064 nm. This light is then > frequency > > doubled with an > > intra-cavity nonlinear element to produce the final output at 532 nm. > > For all this to work > > the optical elements must be critically aligned, and to me the most > amazing > > thing about > > the low selling price is how this alignment is effected so cheaply. One > of > > these units I've > > opened up has the doubler crystal held down by a lump of cement on one > > side- it looks > > for all the world like it must have pushed into alignment and "held" > there > > while the cement > > was cured. Green pointers made in this way are characterized by quite > good > > beam quality > > and very little wavelength spread from unit to unit. However, they are > > generally quite > > delicate and ruined by mechanical shock. > > > > Although not commonly known, at least one outfit (Z-Bolt) is now selling > > "direct diode" > > green pointers, where there is just one laser which emits directly in the > > green, at around > > 515-530 nm. These are much more robust, operate well over a wider > > temperature range, > > but have the usual poor beam quality (non-circular beam with some > residual > > astigmatism) > > characteristic of diode lasers made with simple collimating optics. And, > > the output > > wavelength spread from unit to unit is quite large. > > > > Dana > > > > > > On Mon, Jun 11, 2018 at 2:43 AM, Mark Sims wrote: > > > > > Well, no. Green laser pointers convert a rather high power 800 nm > laser > > > to 1600 nm in one crystal then divide it to 533 nm in another one. > The > > > physics and manufacturing of them is best described as black magic. > They > > > are cheap because China developed the process to grow the crystals in > bulk > > > and crank out zillions of them for consumer products. > > > > > > I suspect that a 1600-ish nm to 800-ish nm converter is not a stock > > > consumer-quantity device and will cost a pretty penny or two... like a > > > red/IR laser diode can be had for 50 cents and a telecom VCSEL diode > can be > > > $500. > > > > > > -- > > > > > > > It cannot be too much, given the fact that these are used in > > > green laser pointers. > > > ___ > > > time-nuts mailing list -- time-nuts@febo.com > > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > > > mailman/listinfo/time-nuts > > > and follow the instructions there. > > > > > ___ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > > and follow the instructions there. > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] HP5065C or the 5065Jr.
Joe, "What is mounted on top of the 10811?" That is a Clifton Labs Z1 buffer amp. Still made but by another company. Mounted on a small right angle bracket that is mounted using the existing screws on the back of the 10811 adaptor assy. It's input is connected to the 10Mhz out pins of the connector for the 10811. It has a high input impedance so as not to load the 10811 and VERY high isolation. That's how I provide the 10Mhz out. I have also used the LH0033 mounted with RTV "dead bug" style on the on the back of the assy. It only requires two resistors and two caps to utilize a single supply. Cheers, Corby ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] where can I purchase 794.7 nm VCSEL for building CPT rubidium clock?
For experimental use you are probably better advised to use a dye laser or a Fabry-Perot laser as both are available on the surplus market and both are ‘tunable’ and leave the VCSEL till you have a functioning prototype On Jun 11, 2018, at 4:29 AM, Dana Whitlow wrote: I should have written more clearly- the adhesive in question was *not* in the optical path. As is usual, variations are possible, one supposedly being that the crystal that lases at 1064 nm is also doped with something to make it nonlinear (so I've read). I kind of have my doubts over this, however it seems like asking too much of a single substance to do "double" duty without some unwanted compromises. Dana On Mon, Jun 11, 2018 at 6:06 AM, Bruce Griffiths wrote: > The better ones use optically contacted crystals to avoid browning of the > adhesive due to the high power densities of the 1064nm laser required for > efficient frequency doubling. > > Brue >> On 11 June 2018 at 22:52 Dana Whitlow wrote: >> >> >> Mark's description about how (most) green laser pointers work The better > is a bit in >> error, and is perhaps >> over-simplified- the reality is actually more fascinating yet: >> >> First a diode laser operating at around 808 or 809 nm is used to > optically >> pump a solid >> state laser which generates light at 1064 nm. This light is then > frequency >> doubled with an >> intra-cavity nonlinear element to produce the final output at 532 nm. >> For all this to work >> the optical elements must be critically aligned, and to me the most > amazing >> thing about >> the low selling price is how this alignment is effected so cheaply. One > of >> these units I've >> opened up has the doubler crystal held down by a lump of cement on one >> side- it looks >> for all the world like it must have pushed into alignment and "held" > there >> while the cement >> was cured. Green pointers made in this way are characterized by quite > good >> beam quality >> and very little wavelength spread from unit to unit. However, they are >> generally quite >> delicate and ruined by mechanical shock. >> >> Although not commonly known, at least one outfit (Z-Bolt) is now selling >> "direct diode" >> green pointers, where there is just one laser which emits directly in the >> green, at around >> 515-530 nm. These are much more robust, operate well over a wider >> temperature range, >> but have the usual poor beam quality (non-circular beam with some > residual >> astigmatism) >> characteristic of diode lasers made with simple collimating optics. And, >> the output >> wavelength spread from unit to unit is quite large. >> >> Dana >> >> >>> On Mon, Jun 11, 2018 at 2:43 AM, Mark Sims wrote: >>> >>> Well, no. Green laser pointers convert a rather high power 800 nm > laser >>> to 1600 nm in one crystal then divide it to 533 nm in another one. > The >>> physics and manufacturing of them is best described as black magic. > They >>> are cheap because China developed the process to grow the crystals in > bulk >>> and crank out zillions of them for consumer products. >>> >>> I suspect that a 1600-ish nm to 800-ish nm converter is not a stock >>> consumer-quantity device and will cost a pretty penny or two... like a >>> red/IR laser diode can be had for 50 cents and a telecom VCSEL diode > can be >>> $500. >>> >>> -- >>> It cannot be too much, given the fact that these are used in >>> green laser pointers. >>> ___ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to https://www.febo.com/cgi-bin/ >>> mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts >> and follow the instructions there. > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Casio Wave Ceptor wrist watch - quick accuracy test
I think you guys won the luck of the draw. I have had a Casio WV200DA-1AV Wave Ceptor for a while, module 3140. Nice watch, but it gains about 1/2 sec per day when not synchronized. I recently got a Casio GW-M5610 G-Shock, module 3153. I have not run it unsychronized, so have not checked its drift, but other G-Shocks have been quite good. It is the higher-end line with tighter specs and they actually have a trimmer inside. David N1HAC On 6/11/18 6:30 AM, Dana Whitlow wrote: I bought a Casio 'atomic watch" about 3 months ago, one which uses the '3405' module. I've also been running checks with radio setting turned off, and mine is coming in at just under 1 sec per month, based on seeing how long it takes to drift one second. But I find that visual/aural coordination is a poor way to do business- if the error is near zero (or an integer number of seconds), my eye/ear/brain will shift to make it look like it's "right on" within a few seconds even if the initial look says it's a little bit off. I hadn't thought of the video approach- sure wish I had a means to record video and then view it frame by frame. Dana On Mon, Jun 11, 2018 at 3:20 AM, Esa Heikkinen wrote: Hi! There seems to be some kind of comeback going on with 80's style digital watches. You may find replicas of some 80's models or even re-makes of the original models from original manufacturer. So I decided to get one. As a time-nut my primary goal was to have radio controlled 'atomic' model. So I ended up to Casio Wave Ceptor WV-59DE-1AVEF. There's many models available from basic digital models like this to very nice ones with with full titanium body (analog style). But because of the 80's is hot it had to be digital... Wave Ceptors suport all time signals formats (US, UK/German and Japan) and correct standard is automatically selected when home city is set. One of the first things to do was to test the accuracy with radio syncronization turned off. Correct time was fist set with DCF77. Then I switched off the synconization. After beign about three days off there was no significiant visible error on time. In the video we can see however about one frame error, which means about 40 milliseconds. Still that's pretty good result for wrist watch. Also, the syncronization will occur once per day when the reception is good. So the watch must be at least calibrated in the factory. Don't know if the watch performs any kind of self-calibration according to radio syncronization results, most likely not - but it would be technically possible. So far so good, it's accurate enough - at least as new. When syncronization is turned on, there should never be visible error on time. Here's my test video: https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3D_A23buFeHd0&data=02%7C01%7Cdavid.g.mcgaw%40dartmouth.edu%7Ca8e76ed2d4b54ed75dce08d5cf866ee5%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C636643098739784325&sdata=EH0F8vRQK0jmROrREGrD9jDMcd2JQglutxZO%2BVff7t0%3D&reserved=0 -- 73s! Esa OH4KJU ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.febo.com%2Fcgi-bin%2Fm&data=02%7C01%7Cdavid.g.mcgaw%40dartmouth.edu%7Ca8e76ed2d4b54ed75dce08d5cf866ee5%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C636643098739784325&sdata=1oe%2FezDZCqH7LxIeCJqwcCwW3wcduBUL8fB2hmcYGTg%3D&reserved=0 ailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.febo.com%2Fcgi-bin%2Fmailman%2Flistinfo%2Ftime-nuts&data=02%7C01%7Cdavid.g.mcgaw%40dartmouth.edu%7Ca8e76ed2d4b54ed75dce08d5cf866ee5%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C636643098739784325&sdata=c7UR5i3YJmWoKCBOn0PTNHsQHAQwE9BjVhouwtdJTBY%3D&reserved=0 and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] a newbie question: where can I purchase 794.7nm VCSEL for building CPT rubidium clock?
Hi Attila, I think your information is very interesting. I didn't realize which type of common LDs can do GHz level modulation (anyway I didn’t have much knowledge on laser diode before). It would be great If you could recommend several good Laser diodes (which vendor/part number) with possible 1-2GHz modulation bandwidth. Thanks! On Mon, 11 Jun 2018 10:57:50 +0200, Attila Kinali wrote: > > On Sat, 9 Jun 2018 16:54:15 +0800 > mimitech mimitech wrote: > > > I prefer the 780/795nm VCSEL scheme for its simplicity. After some > > searching, looks like the 780nm VCSELs are also not easy to source, > > although other types of 780nm LD are common. > > Why are you focusing on VCSEL anyways? Standard laser diodes already > have a modulation bandwidth that goes into several 100MHz, the better > ones should give you 1-2GHz. With that, you should be within 6dB, > maybe 10dB of the CW power. Given that you only need a few 10μW to 100μW > of laser power, and that those diodes are in the 1-30mW range should > give you enough margin. > > > Attila Kinali > -- > It is upon moral qualities that a society is ultimately founded. All > the prosperity and technological sophistication in the world is of no > use without that foundation. > -- Miss Matheson, The Diamond Age, Neil Stephenson ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Raw phase data of super-5065
Attila Kinali writes: > Unfortunately, I have no application that can read XPS files available. > Can you send it as something more standard? Okular opens the file without problems. MuPDF should do the same, but I can't test it at the moment. Regards, Achim. -- +<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+ Waldorf MIDI Implementation & additional documentation: http://Synth.Stromeko.net/Downloads.html#WaldorfDocs ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] a newbie question: where can I purchase 794.7 nm VCSEL for building CPT rubidium clock?
On 06/11/2018 09:52 AM, Attila Kinali wrote: > On Sat, 9 Jun 2018 23:28:29 +0800 > mimitech mimitech wrote: > >> Just do a little bit research on 1560nm telecom laser transceiver. The >> closest wavelength is 1560.61nm (DWDM channel 21) as defined by ITU. >> Usually telecom laser transceiver module uses DFB (distributed feedback) >> type laser diode instead of VCSEL laser. However, the DFB LD should be >> capable of direct modulation, so there maybe not much difference with VCSEL >> in terms of usage. For the modulation bandwidth, I guess a 2.5Gbps module >> should be OK for 1.71GHz analog modulation. > > A 2.5Gbps module should be good even for 3.4GHz modulation. The 3dB frequency > of should be higher than the baud rate used. Besides, even if the 3dB > frequency > is below 3.4GHz, that does not matter, it just means that your sidebands will > be damped (second order low pass, IIRC), but you don't need that much power > anyways. Considering that the bandwidth of the reference receiver for SDH/SONET is 3/4 of the baudrate, and then using a 4-pole Bessel-Thompson filter, I beg to differ regarding the expected bandwidth. The majority of the modulated energy will be inside those 3/4 and you don't want much more as it causes unnecessary problems. But sure, sidebands will be damped and you can expect 6 dB slope there from the bare diode. This is stuff I can actually measure at home as I come to think of it. >> So, imagine I modulated 1.71GHz microwave signal onto 1560nm laser wave, >> then used a KPT non-linear optical crystal to double the frequency, >> hopefully I could get 780nm laser with +/-3.42GHz sideband spectrum, that >> should be suitable to shine on a Rubidium vapor cell and trigger CPT >> effect. I don't know if I understand this process correctly, many details >> must be missed. > > Using a non-linear element will give you lots of intermodulation products. > Ie, your sidebands will be +/-1.71GHz, +/-3.42GHz, +/-6.84GHz,... > So you will have to be a bit carefull with the laser tuning in order to > get the right harmonics. Consider the roll-off of the diode/modulator. Also, expect to servo the amplitude of the modulation for stabilization. This is separate from the servo of the center of wavelength as well as the width of the modulation. CPT has more of these loops than a traditional rubidium. >> Another question is, after passing through the KPT doubler crystal, whether >> the light remains single mode and linear polarization mode or not? If >> someone could provide any relevant information and suggestion, thanks very >> much. > > If I understood the optical process correctly (disclaimer: I'm not > a physicst and have never worked with optical systems), then the multiple > modes are a problem of the laser source, not of the doubler. As multi-modes > are a problem for high speed communication, I expect telecom lasers to > be quite clean. You will have to ensure that you are not operating it > close to a mode jump, though. The DWDM lasers is quite clean and their temperature-stabilization is what you want to have to start with. However, I don't think any of the ones I have will match the frequency needed, but I may be lucky. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Casio Wave Ceptor wrist watch - quick accuracy test
I should have mentioned that my Casio (module 3405) is a G-Shock "diving watch" with a 20-bar (~200m depth) rating. In so far as possible, I never take it off my wrist (TSA check points being the occasional exception), and don't want any leak problems even though I never dive. I once bought a watch rated at 20m, and it only lasted about a month before it leaked. Apparently normal living stresses are equivalent to diving to moderate to substantial depths. Dana On Mon, Jun 11, 2018 at 2:44 PM, David G. McGaw wrote: > I think you guys won the luck of the draw. I have had a Casio WV200DA-1AV > Wave Ceptor for a while, module 3140. Nice watch, but it gains about 1/2 > sec per day when not synchronized. I recently got a Casio GW-M5610 > G-Shock, module 3153. I have not run it unsychronized, so have not checked > its drift, but other G-Shocks have been quite good. It is the higher-end > line with tighter specs and they actually have a trimmer inside. > > David N1HAC > > > > On 6/11/18 6:30 AM, Dana Whitlow wrote: > >> I bought a Casio 'atomic watch" about 3 months ago, one which uses the >> '3405' module. >> I've also been running checks with radio setting turned off, and mine is >> coming in at >> just under 1 sec per month, based on seeing how long it takes to drift one >> second. >> >> But I find that visual/aural coordination is a poor way to do business- if >> the error is near >> zero (or an integer number of seconds), my eye/ear/brain will shift to >> make >> it look like >> it's "right on" within a few seconds even if the initial look says it's a >> little bit off. >> >> I hadn't thought of the video approach- sure wish I had a means to record >> video and >> then view it frame by frame. >> >> Dana >> >> >> On Mon, Jun 11, 2018 at 3:20 AM, Esa Heikkinen wrote: >> >> Hi! >>> >>> There seems to be some kind of comeback going on with 80's style digital >>> watches. You may find replicas of some 80's models or even re-makes of >>> the >>> original models from original manufacturer. >>> >>> So I decided to get one. As a time-nut my primary goal was to have radio >>> controlled 'atomic' model. So I ended up to Casio Wave Ceptor >>> WV-59DE-1AVEF. There's many models available from basic digital models >>> like >>> this to very nice ones with with full titanium body (analog style). But >>> because of the 80's is hot it had to be digital... >>> >>> Wave Ceptors suport all time signals formats (US, UK/German and Japan) >>> and >>> correct standard is automatically selected when home city is set. >>> >>> One of the first things to do was to test the accuracy with radio >>> syncronization turned off. Correct time was fist set with DCF77. Then I >>> switched off the synconization. After beign about three days off there >>> was >>> no significiant visible error on time. In the video we can see however >>> about one frame error, which means about 40 milliseconds. Still that's >>> pretty good result for wrist watch. Also, the syncronization will occur >>> once per day when the reception is good. >>> >>> So the watch must be at least calibrated in the factory. Don't know if >>> the >>> watch performs any kind of self-calibration according to radio >>> syncronization results, most likely not - but it would be technically >>> possible. >>> >>> So far so good, it's accurate enough - at least as new. When >>> syncronization is turned on, there should never be visible error on time. >>> >>> Here's my test video: >>> https://na01.safelinks.protection.outlook.com/?url=https%3A% >>> 2F%2Fwww.youtube.com%2Fwatch%3Fv%3D_A23buFeHd0&data=02% >>> 7C01%7Cdavid.g.mcgaw%40dartmouth.edu%7Ca8e76ed2d4b54ed75dce0 >>> 8d5cf866ee5%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C636 >>> 643098739784325&sdata=EH0F8vRQK0jmROrREGrD9jDMcd2JQglutxZO% >>> 2BVff7t0%3D&reserved=0 >>> >>> -- >>> 73s! >>> Esa >>> OH4KJU >>> ___ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to https://na01.safelinks.protect >>> ion.outlook.com/?url=https%3A%2F%2Fwww.febo.com%2Fcgi-bin% >>> 2Fm&data=02%7C01%7Cdavid.g.mcgaw%40dartmouth.edu%7Ca8e76e >>> d2d4b54ed75dce08d5cf866ee5%7C995b093648d640e5a31ebf689ec9446 >>> f%7C0%7C0%7C636643098739784325&sdata=1oe%2FezDZCqH7LxIeCJqwc >>> CwW3wcduBUL8fB2hmcYGTg%3D&reserved=0 >>> ailman/listinfo/time-nuts >>> and follow the instructions there. >>> >>> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://na01.safelinks.protect >> ion.outlook.com/?url=https%3A%2F%2Fwww.febo.com%2Fcgi-bin% >> 2Fmailman%2Flistinfo%2Ftime-nuts&data=02%7C01%7Cdavid.g. >> mcgaw%40dartmouth.edu%7Ca8e76ed2d4b54ed75dce08d5cf866ee5%7C9 >> 95b093648d640e5a31ebf689ec9446f%7C0%7C0%7C636643098739784325 >> &sdata=c7UR5i3YJmWoKCBOn0PTNHsQHAQwE9BjVhouwtdJTBY%3D&reserved=0 >> and follow the instructions there. >> > > ___ > time-nuts mailing list -- time-nuts@febo.com >
Re: [time-nuts] Casio Wave Ceptor wrist watch - quick accuracy test
I posted about my G-shock watch on this forum probably about 10 years ago. Go look them up. I found mine superbly accurate and being in Tasmania I cannot connect to any LF service. After a while it started to get a little worse and I found you can take the back off and calibrate it. My rechargeable battery has just started to fail and so I've ordered a new one. Jim On Mon, 11 Jun 2018 at 18:20, Esa Heikkinen wrote: > Hi! > > There seems to be some kind of comeback going on with 80's style digital > watches. You may find replicas of some 80's models or even re-makes of > the original models from original manufacturer. > > So I decided to get one. As a time-nut my primary goal was to have radio > controlled 'atomic' model. So I ended up to Casio Wave Ceptor > WV-59DE-1AVEF. There's many models available from basic digital models > like this to very nice ones with with full titanium body (analog style). > But because of the 80's is hot it had to be digital... > > Wave Ceptors suport all time signals formats (US, UK/German and Japan) > and correct standard is automatically selected when home city is set. > > One of the first things to do was to test the accuracy with radio > syncronization turned off. Correct time was fist set with DCF77. Then I > switched off the synconization. After beign about three days off there > was no significiant visible error on time. In the video we can see > however about one frame error, which means about 40 milliseconds. Still > that's pretty good result for wrist watch. Also, the syncronization will > occur once per day when the reception is good. > > So the watch must be at least calibrated in the factory. Don't know if > the watch performs any kind of self-calibration according to radio > syncronization results, most likely not - but it would be technically > possible. > > So far so good, it's accurate enough - at least as new. When > syncronization is turned on, there should never be visible error on time. > > Here's my test video: > https://www.youtube.com/watch?v=_A23buFeHd0 > > -- > 73s! > Esa > OH4KJU > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] I: Re: Raw phase data of super-5065
Da "tim...@timeok.it" tim...@timeok.it A att...@kinali.ch Cc Data Tue, 12 Jun 2018 07:22:26 +0200 Oggetto Re: [time-nuts] Raw phase data of super-5065 Ciao Attila, here the .gif file. Luciano Da "Attila Kinali" att...@kinali.ch A tim...@timeok.it,"Discussion of precise time and frequency measurement" time-nuts@febo.com Cc Data Mon, 11 Jun 2018 11:04:23 +0200 Oggetto Re: [time-nuts] Raw phase data of super-5065 Ciao Luciano, On Fri, 8 Jun 2018 14:05:24 +0200 "tim...@timeok.it" wrote: > Here a ten days simultaneously run of the A and B version compared with my HP Z3816A GPSDO. Thanks a lot! Unfortunately, I have no application that can read XPS files available. Can you send it as something more standard? Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
