Millisecond precise imaging

Hello Doug and Adam,

It’s works but…
We then put the camera on a test bench (cf. description in attached powerpoint file) to check reproducibility of the accuracy and measure the trigger bias, it shows several problems:

1. The triggering command sent to the camera is sometime ignored by the camera.
2. The variation from one trigger delay to another is fluctuating a lot (of up to 60 ms). This is far from our +/- 5 ms need.

Could you please consider this attached problem description. I think that we should schedule a teleconference meeting early next year with engineering teams to try to find a solution to our problem.

In the meantime I which you all a very good Christmastime!

Gautier

 

Hello Doug and Adam,

We were aware of the extra delay you mentioned and we considered it. Beyond this bias that we could correct, the hard point for us is the important jitter described in our report.
I don't really understand, in spite of your explanations, why the "Trigger In" way doesn't not give a very accurate and reproducible timing. Also I don't understand why the flush operation is for, just before an exposure. As Adam, I more suspect the shutter disc mechanism management.

Anyway, as you suggested we will now focus on the "Trigger Out" option, hoping it will accurately tell us the actual open time.

We'll modify consequently our setup and do some measurements for that early January and let you know.

See you in 2017!

Best Regards,

Gautier

 

Hello Doug and Adam,
First of all, I wish you a happy new year!
We managed a couple a days ago to determine the latency between the exposure command and the "real" exposure date by spying the I2C pin 7 (Open Collector Genl Purp Out). There is for us a 60ms bias between the switching state on the I2C output and the real exposure start (when the matrix starts integrating light).
So a priori no need for you to adapt the firmware.
Another question concerning the camera caracteritics: what is the limit external temperature the camera is able to bear without any damages ? Indeed, we plan an observation session in the coming days and external temperature by night is about -15°C to -10°C (5°F to 14°F)... We didn't finf any info on that topic in the camera user manual.
Thanks in advance for your answer.
Best regards,
Gautier

 

Hello Adam,

We are still working on it but we have the following observations to report:
There is no output signal at all from PIN2 (Open Collector Trigger Out) which was the one we supposed to be working with Trigger Out option.
In fact the one working with Trigger Out option is PIN7 "Open Collector Genl. Purp. Out". But its voltage changes from 0.68 V (when shutter is closed) to 0.01 V (when shutter is open).
We expected it to range from 3.3 V to around 0.0 V.
Could you please confirm the range we observed is nominal or our camera has something wrong?

Thanks in advance,

Gautier

 

OK, we will add a pull-up resistor because we don't have some in our current setup.
But then could you please confirm that the voltage range we observed at PIN7: from 0.68 V (when shutter is closed) to 0.01 V (when shutter is open) is nominal?

 

OK! It's clear now. Many thanks!

 

Hello,
We are still in our quest for high accuracy time stamping of our pictures.
For a ultimate refinement, we now have to consider the shutter speed.
According to the User's Manual, the shortest exposure is 0.12 s. My understanding is that this exposure time is induced by the intrinsic shutter speed and then, I can deduce that the shutter speed is 0.12 s to travel the 14.85 mm of the CCD length = 123.75 mm/s in the sensor plane.
Is my assumption correct? and do you have a better knowledge of this value?
Indeed, if correct, the start time of the exposure of one side of the field is different of 0.12 s than at the other side.
A subsidiary question: does the shutter speed is constant or is varying according to the exposure time set?

Thanks in advance for your help!

Gautier

 

Hello Doug,
Thanks for you confirmation of the constant rotation speed.
But please could you also tell me the value of its exact speed.
Does this speed is immediately correlated to the minimum exposure time?
I guess you probably made those measurements in the development of this camera/shutter.

Thanks in advance,

Gautier

 

Hello Doug,

We are not really equiped to make this kind of measurements right here. We made some attempts to determine shutter speed with a smartphone and slow-motion mode but the result is not very accurate...
I guess you probably have better means to determine it on your side or maybe, as you suggested, make some research.

Thanks in advance.

Gautier