physical science unit 
chemical analysis/structure of drug,soil,mineral or any matter. 
biological unit 
includes serology and body secretion. 
fire arm unit 
ballistics,all study about guns and projectile. 
document examination unit 
signature /handwriting analysis. 
photography unit 
forensic photography,infrared,ultraviolet,to monography and X-ray. 
toxicology unit 
features,effects,treatment,and analysis of harmful substance in dead body. 
finger printing unit 
retraction of latent finger prints and then develop them for analysis. 
poly-graph unit 
lie detector. 
voice print analysis 
sound spectro graphy that break the voice pitch and wavelength of voice in a graph. 
blast unit 
analyze powder residue and chemical/bearings used in blast. 
evidence collection unit 
from crime scene to forensic lab,preservation of collection and chain of custody. 
mobile phone unit 
can trace call data and retrieve memory. 
computer retrieval unit 
analyze nature of computer functions in recent past even after data is deleted.
Image source-Google|Image by-Nishka Prajapati |http://www.legalserviceindia.com/legal/article-2987-branches-of-forensic-science.html