Presumably the driver you have will limit the output current to 800 mAmp. This combination is OK cos the diode is more capable than the driver. ie the driver cant really overdrive the diode. Nevertheless, you have a meter to check the actual operating current thru the diode.
The Osram data sheet for the SFH on page 5 shows several graphs. One graph is the 'Total Radiant Flux' and this shows radiant flux at a diode current of 1 amp as a base and then plots the 'RELATIVE' light output at other currents. At 1 amp (ie 10 to the power '0') the relative radiant flux is 1; ie (10 to the power '0'). At a current of one tenth of an amp (10 to the power -1) the RELATIVE power is one tenth of the power at 1 amp. So the diode is quite linear in its light output versus diode current.
At 800 mAmp you will have 0,8 of the light output compared to that at 1 amp.
There is another graph on page 5 which is of interest. This is the 'Permissible Pulse Handling Capability'. This graph shows how to drive the diode in a pulse mode. The square wave in the top RH corner shows D=tp/T so if tp equals T then the diode current is ON all the time and the graph line for D=1 shows a horizontal line at If = 1 amp. If you wanted to run the diode in a pulsed mode to give three times the peak light output compared to the DC mode, then looking at the curve for D=0.33 shows that the peak current varies with the pulse ON time tp. For tp = 10 to the power -5, (0.00001 seconds) the peak current is about 2.3 amp. If the ON time is longer at 0.01 second, then the peak current is only 1.5 amp peak.
For the first case at tp = 10 * -5, the repetition frequency is 30 kilo hertz, and in the second case the repetition frequency is 3 kHz. The first case will give a peak light of 2.3 times the 1 amp DC value, and in the second case the light output will be only 1 1/2 times the 1 amp DC value.
One thing I neglected to mention was that with the ICOP thing, you already had the mechanical arrangement. With what you want to do now, you have a bit of mechanical stuff to do and mostly this involves the heat sink design. There was a good design brief from (I think) texas Instruments. I thought I had it, but cant quickly retrieve it. It was about using solderable types of IGBT transistors on PCB material.
hope this helps.