An optical sensing apparatus comprising: a laser device including a light source that emits laser light, a diffusing member having a diffusing surface that crosses an optical path of the laser light, the diffusing member refracting or diffracting the laser light to make the laser light lower in intensity in a first portion including a center of a cross-section of the laser light that crosses the optical path, make the laser light higher in intensity in a second portion of the laser light that surrounds the first portion in the cross-section, and enlarge a beam diameter of the laser light, and a screen that crosses an optical path of the laser light having passed through the diffusing member such that a spot of light having passed through the screen or having been reflected by the screen appears on a surface of the screen, the beam diameter of the spot forming an apparent light source size of the laser device, the diffusing member being configured such that the laser light spreads at a first substantial spread angle when the laser light passes through the diffusing member, the screen being configured such that the laser light spreads at a second substantial spread angle when the laser light passes through the screen or is reflected by the screen, and the first substantial spread angle being larger than the second substantial spread angle the laser device being configured to irradiate a physical object with the laser light having passed through the screen or the laser light having been reflected by the screen a photodetector that is configured to detect at least a portion of the laser light returning from the physical object and output an electric signal; and a control circuit that is configured to control the laser device and the photodetector, wherein the control circuit causes the laser device to irradiate the physical object with at least one optical pulse of the laser light and causes the photodetector to perform a time-resolved measurement of at least one reflected optical pulse of the laser light returning from the physical object. a laser device including a light source that emits laser light, a diffusing member having a diffusing surface that crosses an optical path of the laser light, the diffusing member refracting or diffracting the laser light to make the laser light lower in intensity in a first portion including a center of a cross-section of the laser light that crosses the optical path, make the laser light higher in intensity in a second portion of the laser light that surrounds the first portion in the cross-section, and enlarge a beam diameter of the laser light, and a screen that crosses an optical path of the laser light having passed through the diffusing member such that a spot of light having passed through the screen or having been reflected by the screen appears on a surface of the screen, the beam diameter of the spot forming an apparent light source size of the laser device, a light source that emits laser light, a diffusing member having a diffusing surface that crosses an optical path of the laser light, the diffusing member refracting or diffracting the laser light to make the laser light lower in intensity in a first portion including a center of a cross-section of the laser light that crosses the optical path, make the laser light higher in intensity in a second portion of the laser light that surrounds the first portion in the cross-section, and enlarge a beam diameter of the laser light, and a screen that crosses an optical path of the laser light having passed through the diffusing member such that a spot of light having passed through the screen or having been reflected by the screen appears on a surface of the screen, the beam diameter of the spot forming an apparent light source size of the laser device, the diffusing member being configured such that the laser light spreads at a first substantial spread angle when the laser light passes through the diffusing member, the screen being configured such that the laser light spreads at a second substantial spread angle when the laser light passes through the screen or is reflected by the screen, and the first substantial spread angle being larger than the second substantial spread angle the laser device being configured to irradiate a physical object with the laser light having passed through the screen or the laser light having been reflected by the screen a photodetector that is configured to detect at least a portion of the laser light returning from the physical object and output an electric signal; and a control circuit that is configured to control the laser device and the photodetector, wherein the control circuit causes the laser device to irradiate the physical object with at least one optical pulse of the laser light and causes the photodetector to perform a time-resolved measurement of at least one reflected optical pulse of the laser light returning from the physical object.