In the experiment, I used a high-speed CCD camera to shoot, and when I shot 500 pictures per second, the picture was very dark. What happened?

In the final analysis, it is still a matter of exposure time.

(1). The ordinary lens you use should have a large luminous flux, and you can take photos with good brightness in a short exposure time. At a speed of 500fps, the exposure time must be very low, and you can take normal photos, which shows that your ordinary lens has a large luminous flux.

(2) You use a magnifying glass, which may be the characteristics of the lens itself: because of the small field of view, high magnification and low luminous flux, which has been confirmed in your later experiments-the picture is clear at100 fps (reducing the frame rate)-indicating that the light intensity of the CCD sensor is not enough.

Solution:

(1). Reduce the frame rate to increase the exposure time. Or set it with PC software to see if you can increase the exposure time as much as possible.

(2) See if there is a lens with a larger luminous flux. Mainly depends on parameters such as coherent aperture and f number.

(3) Use active light source for lighting. Ordinary white LED is used as the external lighting source to increase the illumination intensity of the target, so that the illumination intensity reflected by the target on the photosensitive surface of CCD will also be improved, so that high-brightness photos can be taken under the condition of low exposure time.