A system and method for cross-platform patching of applications. This restrains scattering of light on a long wavelength side of red light, and allows taking images of mucosa, blood vessels, and other tissue in good contrast in an object to be observed and satisfactorily observing them on a monitor. A single arm is pivotal with respect to the upper housing and pivotal with respect to the step in order to form a three-bar linkage for moving the step between the stowed and deployed positions.