An apparatus for inspecting a transparent hollow article , the apparatus comprising at least one light source for emitting light energy at a portion of the transparent hollow article as the transparent hollow article moves along a travel path past the at least one light source, wherein the light energy emitted by the at least one light source comprises: light energy at a first, absorption wavelength that is primarily absorbed by the portion of the transparent hollow article; and light energy at a second, reference wavelength that is not primarily absorbed by the portion of the transparent hollow article, the apparatus is characterized by at least one light sensor for sensing light energy emitted by the at least one light source that is reflected by the portion of the transparent hollow article to the light sensor assembly, wherein the at least one light sensor is on the same side of the travel path of the transparent hollow article as the at least one light source; and a processor in communication with the at least one light sensor, wherein the processor is programmed to compute a wall thickness of the portion of the transparent hollow article based on an intensity of light energy sensed by the at least one light sensor. at least one light source for emitting light energy at a portion of the transparent hollow article as the transparent hollow article moves along a travel path past the at least one light source, wherein the light energy emitted by the at least one light source comprises: light energy at a first, absorption wavelength that is primarily absorbed by the portion of the transparent hollow article; and light energy at a second, reference wavelength that is not primarily absorbed by the portion of the transparent hollow article, the apparatus is characterized by at least one light sensor for sensing light energy emitted by the at least one light source that is reflected by the portion of the transparent hollow article to the light sensor assembly, wherein the at least one light sensor is on the same side of the travel path of the transparent hollow article as the at least one light source; and a processor in communication with the at least one light sensor, wherein the processor is programmed to compute a wall thickness of the portion of the transparent hollow article based on an intensity of light energy sensed by the at least one light sensor. light energy at a first, absorption wavelength that is primarily absorbed by the portion of the transparent hollow article; and light energy at a second, reference wavelength that is not primarily absorbed by the portion of the transparent hollow article, the apparatus is characterized by at least one light sensor for sensing light energy emitted by the at least one light source that is reflected by the portion of the transparent hollow article to the light sensor assembly, wherein the at least one light sensor is on the same side of the travel path of the transparent hollow article as the at least one light source; and a processor in communication with the at least one light sensor, wherein the processor is programmed to compute a wall thickness of the portion of the transparent hollow article based on an intensity of light energy sensed by the at least one light sensor. <EOS>