Hemdé was a French trade­mark for pho­tog­ra­phy acces­sories and stere­o­scopes, named after its loca­tion in Hem and its founder, Mau­rice Delé­caille. Ini­tial­ly focused on pho­to­graph­ic glass plate devel­op­ment, the com­pa­ny patent­ed a stere­o­scope mech­a­nism in 1907 in col­lab­o­ra­tion with Émile Cuny and Paul Sorel. After the dis­so­lu­tion of Delécaille’s com­pa­ny in 1909, Sorel con­tin­ued pro­duc­ing Hemdé stere­o­scopes. The com­pa­ny ceased oper­a­tions some­time in the mid-1920s.
One of Hemdé’s spe­cial­ties was the use of wood­en slide trays. Far more impor­tant was their crank mech­a­nism incor­po­rat­ing a inge­nious­ly thread­ed rod that serves for both lift­ing the slides into view­ing posi­tion and mov­ing the tray, allow­ing smooth for­ward and back­ward navigation.