Methods and devices for standoff differential Raman spectroscopy with increased eye safety and decreased risk of explosion

A system for Raman spectroscopy, the system comprising:

• a laser to emit a ranging beam;
• a telescope, in optical communication with the laser, to illuminate a sample with the ranging beam;
• a camera to acquire an image of a spot formed by the ranging beam on the sample;
• a controller, operably coupled to the camera, to determine a focus of the telescope based on a position of the spot in the image;
• an actuator, operably coupled to the controller and to the telescope, to adjust the focus of the telescope in response to a command from the controller;
• a Raman pump laser, in optical communication with the telescope, to illuminate the sample with a Raman pump beam;
• a spectrometer, in optical communication with the telescope, to measure a spectrum of a Raman signal scattered by the sample in response to the Raman pump beam;
• a beam-steering element, in optical communication with the Raman pump laser and the telescope, to scan the Raman pump beam across the sample so as to reduce a risk of igniting the sample with the Raman pump beam;
• and
• a touchscreen, operably coupled to the camera, to display the image of the sample to a user and to receive an input from a user.