Laser shutter turns off too soon

[Cody-G]

When Imagine generates its own waveforms internally it switches off the laser between stacks. I've noticed that this switch happens just a little too soon, before the last frame of the stack has finished exposing. That means the last frame is dimmer than the rest.

I didn't look closely but my guess is that the laser TTL signal goes low immediately after the last camera TTL pulse is triggered. When the exposure trigger mode is External Start then this means the laser can switch off before the camera is finished exposing the last frame (depending on the chosen exposure time). Like I said it's just a guess, @kdw503 does that sound reasonable?

[kdw503]

I think Imagine gives extra laser shutter open time even after last camera TTL pulse become low.
Here is an example timing generated by Imagine.

Can you send me the .json file? It would be saved with same file name in general tab except extension.
And, configuration file also?

[Cody-G]

Sure I'll email you the .json, .imagine, .ai, and .di files. I didn't save a gui configuration file unforetunately. But I think from the .imagine file and from my memory we can figure out what the gui settings were.

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On Mon, Mar 12, 2018 at 10:38 AM, Dae Woo Kim ***@***.***> wrote: I think Imagine gives extra laser shutter open time even after last camera TTL pulse become low. Here is an example timing generated by Imagine. [image: t1] <https://user-images.githubusercontent.com/23037534/37293298-e3f0d4ca-25e0-11e8-8cc7-eaafeff8eba9.jpg> Can you send me the .json file? It would be saved with same file name in general tab except extension. And, configuration file also? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#63 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AE78hD8jK_Sj5l8siFCXeENYqqokdPv4ks5tdpZ7gaJpZM4SldWO> .

[kdw503]

I saw the waveform. But there is extra laser on time after camera pulse become low.

Do you think we need more extra laser on time?

[Cody-G]

This is a puzzle. The waveform looks fine, the laser pulse stays high for plenty of time after the camera pulse finishes. Is there any way that the waveform that gets executed can be different from the one that's written to file? Maybe the "idle time between stacks" setting is interfering somehow? Another unusual aspect of that recording was that the piezo start and stop position were the same. But I don't see how that should matter. Unfortunately I'm not in town so I can't try to reproduce the issue now.

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On Tue, Mar 13, 2018 at 11:00 AM, Dae Woo Kim ***@***.***> wrote: I saw the waveform. But there is extra laser on time after camera pulse become low. [image: laser] <https://user-images.githubusercontent.com/23037534/37353337-25a59366-26ad-11e8-9bad-b31d496382e8.jpg> Do you think we need more extra laser on time? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#63 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AE78hJQyPCdKvCR1piiwX1HgT4mGrJbCks5td-0pgaJpZM4SldWO> .

[kdw503]

I think the waveform that get executed would be same as the one displayed in waveform tab because it uses same decoding function. But, I will check with oscilloscope.

[kdw503]

I captured those signals at ocpi-2. The yellow pulse is laser and cyan pule is camera1 (I didn't captured camera2).

[Cody-G]

Great that you captured it, thanks! It does look correct. It's still a mystery then why the last frame is dimmer. I did several recordings with similar settings and got the same result every time, so it seems like a real issue. Did you make that recording with the waveform file that I sent you, or did you use the same settings in the GUI and let Imagine create the waveform again? I think the next step should be to make sure that we can replicate the dim images using the same gui settings, but I can't do that now. We can wait until I'm back, or if you want to try it you could use one of the bead samples that are in the WUCCI.

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On Tue, Mar 13, 2018 at 2:53 PM, Dae Woo Kim ***@***.***> wrote: I captured those signals at ocpi-2. The yellow pulse is laser and cyan pule is camera1 (I didn't captured camera2). [image: 20180313_143614] <https://user-images.githubusercontent.com/23037534/37366312-1bc0babc-26ce-11e8-811b-1877c252311a.jpg> — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#63 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AE78hPEcG2veN4roYuiXtpfJ6QTcvAV1ks5teCPVgaJpZM4SldWO> .

[kdw503]

I used the one you sent to me. Is it ok with you if we do the next step when you come back?

[Cody-G]

Sure we can do that

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On Tue, Mar 13, 2018 at 3:25 PM, Dae Woo Kim ***@***.***> wrote: I used the one you sent to me. Is it ok with you if we do the next step when you come back? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#63 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AE78hIgFPR8YC4I7Q5dxpKy7w1XQI28Gks5teCtAgaJpZM4SldWO> .