DLPDLCR2000EVM: Running Blue LED in Continuous Wave ( CW) Mode

Part Number: DLPDLCR2000EVM

I'm interested in using this projector to make a patterned photostimulator for optogenetics /  neurophotonics. The 450 nm LED on the device would be great for stimulating Channelrhodopsin but it's important to have temporal control of the light patterning. Typically one would like to be able to control the frequency between 10-70 Hz and the duration of the pulse between 1-25 ms. 

I was able to get the board to output only blue. Through this link I was also able to figure out how to set the diode current levels. However, even when have this set to just blue, when I put it on a diode and look on it on the oscilloscope I see that the blue is still just pulsing, in this case at ~120 Hz. 

I believe this pulsing is controlled by the LED select output on the DLPC2607 and the strobe controller on the DLPA1000. Is there anyway for me to just get the blue LED to be in a constant on or constant wave ( CW )  mode? If I some how spliced into the LED select traces would I be able to get the DPLA1000 to output in CW mode and even On/Off modulate it with the same line at the desired temporal frequencies (20 Hz, 5 ms on for 10-40 pulses). 



Blue output on diode

2 Replies

  • Hi Gregory,
    Welcome to DLP forum and thank you for your interest in DLP technology.
    I would like to get better understanding of your requirement. Could you please describe in detail requirement about how the light pulse ex. frequency, period and timing within a frame.

    In case DLPDLCR2000EVM, DMD mirrors are also switching multiple times with-in a frame. The light out pattern you observed may be due combination of both.

  • In reply to Vivek Thakur:

    Hi Vivek,

           Within a frame we just want things constant, CW. What I want to do is get a constant pattern on the DMD and flash it on the sample via modulating the 450 nm LED that is illuminating the DMD. 

           For temporal characteristics of the light, we'd want to be able to go as short as a single 1 ms pulse and as long as 140, 1 ms pulses with a repetition rate of 70 Hz. 5-10ms pulses may also work. We will need to play with the temporal characteristics (pulse duration, number of pulses, and repetition rate) experimentally to get the biological/physiological responses we are trying to elicit. 

           More advanced stimulation will involve applying pattern, blinking it at a given stimulation setting (pulse duration, number of pulses, and repetition rate) and then applying a different pattern to target different neruons. 

           Hopefully, this adds clarity & I the DLPDLCR2000 can be pushed to be able to do this.