Boil the sugar in the water until it has completely dissolved. Let cool down.
Puree the raspberries (defrost frozen ones beforehand). Mix the sugar water and the raspberries together and strain them through a fine sieve until the raspberry liquid is separated from the seeds. Then stir in the lemon juice.
Then add the vodka and bottle everything together and store in the refrigerator. Makes about 3 bottles of liqueur.