A coaxial thermal lens microscope was used to generate images based on both the absorbance and thermal diffusivity of histological samples. A pump beam was modulated at frequencies ranging from $50\mathrm{kHz}$ to $5\mathrm{MHz}$ using an acousto-optic modulator. The pump and a CW probe beam were combined with a dichroic mirror, directed into an inverted microscope, and focused onto the specimen. The change in the transmitted probe beam’s center intensity was detected with a photodiode. The photodiode’s signal and a reference signal from the modulator were sent to a high-speed lock-in amplifier. The in-phase and quadrature signals were recorded as a sample was translated through the focused beams and used to generate images based on the amplitude and phase of the lock-in amplifier’s signal. The amplitude is related to the absorbance and the phase is related to the thermal diffusivity of the sample. Thin sections of stained liver and bone tissues were imaged; the contrast and signal-to-noise ratio of the phase image was highest at frequencies from $0.1–1\mathrm{MHz}$ and dropped at higher frequencies. The spatial resolution was $2.5\mathrm{\mu m}$ for both amplitude and phase images, limited by the pump beam spot size.