by Din » Tue May 10, 2016 12:32 pm
John Klayer wrote:Yeah, I thought that too but wouldn't the extra object light without the accompanying reference beam have just added noise to degrade the image, not improve it?
Not necessarily.
Consider the reason for the noise. If you over-modulate with a higher object beam, you "flatten" the sinusoidal peaks. This results in Fourier components in your grating. Some of these components are low frequency. Thus, the low frequency grating diffract at small angles and throw a halo around the object - noise. So, it very much depends on the ratio (I'm assuming you did have some reference - your statement "without the accompanying reference" seems to indicate that there was no ref), the way you develop, the angle of the ref, which presumably was not the angle you intended, since the ref fibre fell out and, also presumably, hit the floor and so hit the plate at some other angle than the one intended, among other factors. Also, was there a colour shift? It may be that the photopic at the colour of the recon is greater than that of the previous shots, thus making it seem brighter.
[quote="John Klayer"]Yeah, I thought that too but wouldn't the extra object light without the accompanying reference beam have just added noise to degrade the image, not improve it?[/quote]
Not necessarily.
Consider the reason for the noise. If you over-modulate with a higher object beam, you "flatten" the sinusoidal peaks. This results in Fourier components in your grating. Some of these components are low frequency. Thus, the low frequency grating diffract at small angles and throw a halo around the object - noise. So, it very much depends on the ratio (I'm assuming you did have some reference - your statement "without the accompanying reference" seems to indicate that there was no ref), the way you develop, the angle of the ref, which presumably was not the angle you intended, since the ref fibre fell out and, also presumably, hit the floor and so hit the plate at some other angle than the one intended, among other factors. Also, was there a colour shift? It may be that the photopic at the colour of the recon is greater than that of the previous shots, thus making it seem brighter.