An image forming apparatus includes a scanner unit to read an original document, an image data storage unit to store read image data, a print unit to print out the image data, a sheet insertion designation unit to perform a sheet insertion processing and a sheet insertion control unit. The present invention relates to the use of two different methods, either each by itself or in combination, to enhance the stiffness, strength, maximum possible use temperature, and environmental resistance of such particles. The spectrometer probe 50 comprises a housing 52 having an aperture 55 and a fiber optic cable 60 having a fiber optic tip 65.